- Seed Stratification: What Seeds Require Cold Treatment
- What is Stratification?
- Is Cold Stratification of Seeds Necessary?
- What Seeds Require Cold Treatment?
- Cold Stratification and Storage
- Germination of Tree Seed
- How To Cold Stratify Seeds For Spring Planting
- Cold Stratify Seeds: Why Not Just Sow The Seed?
- Cold Stratify Seeds: Varieties
- Cold Stratify Seeds: Gather Materials
- Cold Stratify Seeds: Step by Step Process
- How to Stratify seeds
- How Long to Cold Stratify Seeds
- Lazy Seed Stratification
- Cold Stratification In the Garden
- Seeds that Don’t Require Cold Stratification
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- Garden Seeds
- *Some species in this genus require a double cold stratification: that is, two cold treatments separated by warm one, to germinate well. Try two to three months of cold followed by two months of warmth, then again two to three months of cold. When you expose them to warmth after these repeated treatments, most will germinate quite readily.
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- How To Grow Lavender From Seed
- Types of Lavender
- Learn About Growing Lavender
Seed Stratification: What Seeds Require Cold Treatment
When it comes to seed germination, many people don’t realize that some seeds require cold treatment in order for them to sprout properly. Continue reading to learn more about this cold treatment for seeds and which seeds require cold treatment or stratification.
What is Stratification?
In nature, seeds require certain conditions in order to germinate. Seed stratification is the process whereby seed dormancy is broken in order to promote this germination. In order for the stratification of seeds to be successful, it is necessary to mimic the exact conditions that they require when breaking dormancy in nature.
Some seeds require a warm and moist treatment, while others require a cool and wet treatment. Even still, other seeds require a combination of both warm and cool treatments followed by a warm treatment, or a combination of warm and cool moist followed by a dry cycle and warm period to germinate. Therefore, knowing what seeds require to break dormancy is critical before beginning any seed stratification project.
Is Cold Stratification of Seeds Necessary?
So, when is cold stratification of seeds necessary? Cold treatment for seeds is necessary for plants or trees that require time in the ground over winter in order to germinate.
If you are starting cold treatment in the late summer or fall, you can put the seeds in a pot of soil and dig the pot into the ground. The seeds will sprout in the spring. However, if you are starting treatment in the early season, you will want to soak seeds for 12 to 24 hours and put them in a plastic bag or sealable container with equal amounts for sand and peat.
Seal the bag or container and place it in the refrigerator for 10 days. Label the container or bag so that you know which seeds they are. Check the seeds regularly to be sure that the planting medium is moist. Check the seeds after 10 days to see if they are sprouting, as some seeds may require a longer period of cold and wet conditions. (Some seeds even require time in the freezer to break dormancy.)
What Seeds Require Cold Treatment?
Many plants require cold seed stratification in order to break the dormancy cycle and germinate. The following are some common plants requiring a cold treatment for seeds (Note: This is not an all-inclusive list. Be sure to research the germination needs of your particular plants beforehand):
- Butterfly bush
- False sunflower
- Hardy hibiscus
- Evening primrose
- Perennial sweet pea
- Rudbeckia (black eyed susan)
- Chinese lantern
Native Seed Germination Codes and Instructions
The seeds of many native plants have built-in dormancy mechanisms which protect them from germinating before killing frosts or in times of drought. In the wild, seeds will lie dormant until the proper conditions for growth occur. But in cultivation, the successful gardener must become familiar with several simple pre-sowing seed treatment methods which will unlock the dormancy mechanism and stimulate quicker, more consistent germination.
At Prairie Moon Nursery we have developed the following seed germination codes to help you successfully grow the native seed sold through our catalog and online store. These seed treatment suggestions have been compiled from our own experience, available literature, and feedback from other growers and customers. These are only suggestions and not the definitive source of germination information. If your experience reveals successful methods other than these, please let us know.
Until you are ready to plant or apply pre-sowing treatment, seed should be stored in either a sealed (airtight) container under refrigeration (33–38°F) or in an open container in a cool, dry place. Avoid rapid or frequent temperature changes and protect against rodents. Sow seeds shallowly and keep seedlings carefully weeded. Periodic watering is helpful to establish seedlings. If seed does not germinate the first year, don’t give up; germination may occur the second year or even later.
A: Seed should germinate upon sowing in a warm location. No pretreatment is necessary other than cold, dry storage (also called dry cold stratification). Seed purchased from Prairie Moon has been stored under these conditions.
B: Hot water treatment
Bring water to a boil. Remove from heat, pour over seeds and soak in a warm place for 24 hours before planting.
C: (Number of stratifying days): Seeds germinate after a period of cold, moist stratification (click for a picture tutorial on how to artificially stratify)
Please note: You do not need to stratify if you are fall planting or using a seed drill. Also, do not use this method if you are planting a seed mix and cannot keep the site moist.
Mix seeds with equal amounts or more of damp sand, vermiculite, or other sterile media (moist—but not so wet that water will squeeze out of a handful). We use fine sand (available for sale) for small quantities. For large quantities we use medium or coarse grade vermiculite. Place mixture in a labeled, sealed plastic bag and store in a refrigerator (33–38°F). Stratify for the # days indicated in parentheses. If two months (C(60)) of this cold storage before planting is normally required to break the dormancy of these seeds, one month may work for many species if time is a constraint. Some seeds may sprout in the storage bag if moist stratified too long. If sprouting occurs, plant immediately. Another method of breaking dormancy for species requiring moist stratification is to sow seeds outdoors in the fall so they may overwinter.
D: Seeds are very small or need light to naturally break dormancy and germinate
Sow seeds in a container (pot or flat) and water from the bottom as necessary. Seed requiring this treatment should not be covered after sowing, although a light dusting of soil can be applied. If grown in outdoor beds, sow seeds on level soil. Cover with a single layer of burlap or cotton sheet. Do not let soil dry out until seedlings are established. Remove cover after germination. Shading with a window screen set 12″ above the soil the first season will help prevent drying.
E: In order to germinate, seeds need a warm, moist period followed by a cold, moist period
Mix seeds with damp sand (not dripping wet), place in a labeled, sealed plastic bag and store in warm (about 80°F) place for 60–90 days. Then place in refrigerator (33–38°F) for 60–90 days before sowing. Or, sow outdoors and allow one full year for germination.
F: Seeds need a cold, moist period followed by a warm, moist period followed by a 2nd cold, moist period
Seeds germinate after alternating, cold moist, warm moist, cold moist stratification treatments. Start by following instructions for code C, then store in warm (70 to 80 degrees F) place followed by a 2nd cold period. Or sow outdoors and allow 2 year or longer to germinate.
G: Seeds germinate most successfully in cool soil
Sow seeds in late fall (after hard frost) or early spring.
H: Seeds need scarification
One way to accomplish this is by rubbing seed between two sheets of medium grit sandpaper. The object is to abrade seed coats—stop if seeds are being crushed. Scarification should be done before moist, cold stratification (Code C) if this treatment is also needed. Seed purchased from Prairie Moon Nursery has been scarified before shipment. Exception: seed which will be dormant (fall) or frost (winter) seeded outdoors are not scarified to prevent the chance of premature germination and winter kill. If you are ordering seed in the fall for green-house plug production please let us know and we will scarify.
I: Legume, Rhizobium Inoculum
These species are legumes and although they will show satisfactory growth without inoculation we recommend using an inoculum if the proper type is available. The fixation of atmospheric nitrogen improves the long-term health of native plant communities and is especially important in low fertility soils. Prairie Moon Nursery supplies inoculum (when available) at no charge for legume seed purchased from us.
J: We remove the hulls from these legume seeds
This gives more seeds per pound and greatly improves germination. If you have unhulled seed from another source, treat as in Code H.
K: Hemiparasitic species which needs a host plant
Good hosts for many parasitic species include low-growing grasses and sedges: Hairy or Blue Grama, Little Bluestem, Common Oak Sedge, and June Grass. With a knife make a 2″ deep cut at the base of the host plant. Sow seeds in the cut, making sure seed is not more than 1/8″ deep. If host is transplanted at sowing time, the cut is not needed because damaged roots will be available for attachment by the hemiparasite. You may also try sowing seeds of the host and parasitic species together. To add hemiparasitic species to existing sites, scatter seed on soil surface (rake in if seed is large) in late fall.
L: Plant fresh seed or keep moist
Refrigerate until planting or starting other treatment.
M: Best planted outdoors in the fall
N: Special seed treatment, indicated by the addition of blue or green dye (potassium nitrate), has been added to aid in germination. Best planted in spring when soil is warm.
O: Seed needs nicking
Nick seed coat with a knife, soak in water overnight. Plant.
S: Fern spore sowing
Sow fern spores on sterile peat under glass in indirect light. Water with distilled water. Refer to other reference material on growing ferns. Or, direct sow spores on soil surface.
?: Not sure
Your input would be of interest to us.
Prairie Moon Nursery 32115 Prairie Lane Winona, MN 55987 Toll-Free: 1-866-417-8156
Cold Stratification and Storage
Definition of Cold Stratification:
Pre-treating seeds (cold stratification) is a simple measure you can take which will break a seed’s dormancy causing the seed to be more ready to germinate. By subjecting the seeds to this pre-treatment you are really only providing them with the effect that mother nature would have had on the seeds had they been left to their natural course. However by applying the pre-treatment yourself in a controlled environment such as your refrigerator, you are speeding the process up and are better able to control and diminish factors detrimental to a seed’s survival had it been left to make it on its own in the wild. By cold stratifying the seeds you are able to affect the time frame under which the seeds will germinate. By not cold stratifying the seeds (Strategy 2.) you will have to be content to accept nature’s timeframe.
Cold Stratification, there’s a couple different ways to accomplish cold stratification. The first is:
Mix your tree seeds in a clean plastic sealed or ziplock bag with thoroughly moistened vermiculite or peat and place in the bottom vegetable/fruit compartment of your refrigerator. DO NOT PUT IN THE FREEZER!!! It is important to thoroughly but only slightly dampen the vermiculite or peat. Excessive moisture can cause your seeds to mildew and grow moldy. You should not be able to squeeze any dripping water out of a handful of peat or vermiculite after thoroughly and uniformly moistening it. You can also completely moisten the peat then squeeze all the water out of it. I’ve also heard that placing the seeds in a damp paper towel will work also and placing them in the refridgerator. Also some people use moist white sand so they can keep an eye on the seeds and if any start to germinate in stratification they can be removed and planted.
You can also use a little fungicide when moistening your stratifying vermiculite or peat so as to help prevent mould or fungus outbreaks.
Some seeds will actually start to germinate during this process.
After undergoing the recommended period of cold stratification in your refrigerator the seeds are ready to be removed and sown in a warm situation in flats, the nursery bed or pot for germination. Preferably one should try to time this event to occur with Spring.
The Second Way to Cold Stratification is what I consider the easy way, to let mother nature do the work. To plant the seeds outdoors in a seedbed or nursery bed in the fall. The best time in the fall is about the time when the first frosts start to occur. If doing this it’s a good idea to place mulch over the seeds to prevent them from being uncovered by the elements of weather (wind, rain, snow).
Also one last thing, all seedlings, whether grown in pots or beds benefit from good air circulation which wards off fungus growth and promotes sturdy stems.
And some recommendations growers should keep in mind when it comes to growing trees from seeds:
1.Seed germination is more of an art than a science.
2.Be patient when cold stratifying seeds, give them the recommended time and a few days or weeks extra for good measure.
3.You will find some batches of seeds sprouting before you expected and some later than expected.
4.Don’t give up on any seeds that you planted but did not germinate immediately, this is to frequent of an outcome by growers and they will more often than not come up in the next spring. They usually just need more time to overcome their dormancy.
5.Pre-treated seeds like moist warm situations for germinating, not sopping wet cold situations.
6.Use clean or new soils and vermiculite whenever possible. Don’t over water, over dampen anything.
7.You don’t have to cold stratify if you don’t want. Sow them in the Fall in a mulched seedbed or garden area for germination the following Spring. Its been working this way for several thousands of years.
Seeds can be stored in a fridgerator if not planting when the seeds arrive in the mail. Trees seeds will usually keep for a year or so in a refridgerator. The colder the seeds are kept, the longer they will stay viable. You do not what to freeze the seeds.
If you have anymore question feel free to ask by emailing me at [email protected] Thank You for viewing my store.
For some seeds, all that is needed to germinate is warmth and moisture. However, for others, germination only takes place once the seeds have experienced the appropriate number of cold/warm cycles. It’s similar to fruiting trees and berries – a specific number of “chill hours” is needed in order to set the fruit.
With seeds, stratification provides an approximation to what the seed would experience in the natural world. By alternately cooling and warming seeds, and ensuring they are seated in a good growing environment, you can trick them into germinating. In most cases, stratification is a better fit for perennials rather than annuals, though.
In order to stratify seeds, you will need to place them in an appropriate rooting material. This could be peat, or it could be something as simple as a moistened paper towel. For cold stratification (seeds requiring chill hours), you’ll need to store them and their growing material in a cool place, generally refrigerator temperature. For seeds that require warm stratification, you would store them somewhere with a temperature between 68 and 85 degrees F (the average room temperature in your home may be perfect).
Check your seeds regularly for signs of activity. The length of time they need to spend in stratification will vary greatly depending on the type of seed in question. Note that there are some seeds that need both stratification and scarification, such as Baptisia. Scarification is the process of cracking a hard, outer coating to allow the seed to germinate.
Germination of Tree Seed
Germination of Tree Seed
Growing trees from seed can be fun. However, the seed of most tree species won’t germinate immediately when planted because they are in a dormant state. Dormancy must be broken before the seed can germinate.
In some tree species, dormancy is the result of a thick, hard seed coat. The seed coat may be broken in a variety of ways and the process is referred to as scarification. Mechanical means, such as a metal file or coarse sandpaper, can be used to break the seed coat. Treatment with boiling water has also been successful for a number of tree species. In nature, the seed coat may be broken by microbial action, passage of the seed through the digestive tract of a bird or other animal, exposure to alternate freezing and thawing, or fire.
The seed of many tree species will not germinate until they have been exposed to cool temperatures and moist conditions for several weeks or months. Winter weather in Iowa provides the necessary conditions to break dormancy. Gardeners can accomplish the same results by a process called stratification. Tree seed can be stratified by placing the seed in a moist 50:50 mixture of sand and peat moss. Suitable containers include coffee cans, plastic jars, and cottage cheese containers. (Punch holes in the lid of the container to provide air.) Seed can also be stratified in plastic bags. Stratify the seed in the refrigerator.
The seed of some trees, such as redbud, have hard impermeable seed coats and dormant embryos. They require both scarification and stratification for germination.
Specific information on collecting and planting seed from several tree species follows.
Maples (Acer species)
When mature, maple fruit (samaras) turn from green to yellow or brown and fall to the ground. Collect mature fruit from the lawn, driveway, or gutters. There is no need to remove the seed from the fruit.
The fruit of red (Acer rubrum) and silver maple (Acer saccharinum) mature in late spring or early summer. Neither requires a pregermination treatment and should be planted immediately. The fruit of most maple species mature in the fall. Sow seed directly outdoors in the fall or plant stratified seed in the spring. Seed of the sugar maple (Acer saccharum) should be stratified for 40 to 90 days at 33 to 41 F, while seed of the Norway maple (Acer platanoides) require 90 to 120 days at 41 F. Plant the seed (fruit) 1/4 to 1 inch deep.
Horsechestnuts and Buckeyes (Aesculus species)
Gather the fruit (capsules) of the horsechestnuts and buckeyes as soon as they fall to the ground. Dry the fruit at room temperature until the capsules split open, then remove the shiny, dark brown seeds.
Plant the seed in the fall or stratify the seed and plant in the spring. The Ohio buckeye (Aesculus glabra) and common horsechestnut (Aesculus hippocastanum) should be stratified for 120 days at 41 F. Seed should be planted 1 to 2 inches deep.
Hickories (Carya species)
Collect the fruit as they fall to the ground. Remove the husks by hand. Sow the seed in the fall or plant stratified seed in the spring. Prior to stratifying, soak the nuts in water at room temperature for 2 to 4 days (change the water once or twice a day). Then stratify the nuts of the shagbark (Carya ovata) and bitternut (Carya cordiformis) hickories at 33 to 40 F for 90 to 120 days. Pecans (Carya illinoiensis) require only 30 to 90 days of cold stratification. Plant the seeds 3/4 to 1 1/2 inches deep.
Redbud (Cercis canadensis)
Collect the pods of redbud when they turn brown in the fall. Air dry the pods, then remove the seed. Seed of the redbud have hard, impermeable seed coats in addition to dormant embryos. Seed require both scarification and cold stratification before they will germinate. Redbud seed can be scarified by soaking seed in concentrated sulfuric acid for 30 minutes or by submerging seed in boiling water for one minute. Once scarified, the seed should be stratified at 35 to 41 F for 5 to 8 weeks. Seed should be planted promptly at a depth of 1/4 inch.
Kentucky Coffeetree (Gymnocladus dioicus)
Collect the fruit (pods) when they drop to the ground in the fall. Remove the seed by hand. The seed of Kentucky coffeetree have hard, thick seed coats. The seed coat can be broken by filing through it with a hand file. Plant the seed in the spring at a depth of 1 inch.
Black Walnuts (Juglans nigra)
Collect walnuts after they fall to the ground. Remove the husks, then place the nuts in water. Those nuts that float on the water are not viable and can be discarded. The good, viable nuts will sink to the bottom. Sow walnuts in the fall or stratify the nuts at 34 to 41 F for 90 to 120 days and plant in the spring. Walnuts should be planted 1 to 2 inches deep.
Apples and Crabapples (Malus species)
Most apples and crabapples will not reproduce true from seed. They are usually propagated by grafting and budding. However, the seed of most apples and crabapples are viable and can be germinated.
Collect fruit from trees as they ripen. Remove the seed. Sow the seed in the fall or stratify the seed for 60 to 120 days at 37 to 41 F and plant in the spring. Sow the seed 1/2 to 1 inch deep.
Cherry, Peach, and Plum (Prunus species)
Harvest fruit when full mature. Remove the seed. Seed may be sown in the fall or stratified seed may be planted in the spring. Stratify the seeds at 33 to 41 F. The sour cherry (Prunus cerasus) requires 90 to 150 days, the peach (Prunus persica) 98 to 105 days, and European plum (Prunus domestica) 90 days. Seed of plums and peaches should be planted 2 inches deep. Sow the seed of sour cherry at a depth of 1/2 inch. (Like the apples and crabapples, the seed of most cultivated cherries, plums, and peaches will not reproduce true from seed.)
Oaks (Quercus species)
Ripe acorns should be collected as soon as they fall to the ground. Sound, viable seed can be separated from damaged or unfilled acorns by placing them in water. Sound acorns will sink. Most of the floating acorns are not viable and can be discarded.
The acorns of white oak (Quercus alba) and swamp white oak (Quercus bicolor) should be planted in the fall. They will germinate immediately after sowing.
Acorns of bur (Quercus macrocarpa), pin (Quercus palustris), and red (Quercus rubra) oaks can be planted in the fall or stratified seed can be sown in spring. Stratify the seed at a temperature of 32 to 41 F. Acorns of the bur oak require 30 to 60 days, while red and pin oaks require 30 to 45 days.
Excellent references on the propagation of trees and shrubs include
- The Reference Manual of Woody Plant Propagation by Michael Dirr and Charles Heuser Jr.,
- Plant Propagation: Principles and Practices by Hudson Hartmann, Dale Kester, Fred Davies Jr., and Robert Geneve, and
- Seeds of Woody Plants in North America by James Young and Cheryl Young.
This article originally appeared in the August 11, 2000 issue, pp. 102-103.
How To Cold Stratify Seeds For Spring Planting
Many native varieties, like Prairie Coneflower, require cold stratification if seeding in spring. The good news is this is an easy process for any gardener.
Many wildflowers—especially native varieties—have clever mechanisms in place that help protect them from germinating too early in the spring or too late in the summer. These varieties re-seed naturally in the wild and stay dormant until the proper time for them to start sprouting. More and more gardeners are seeing the benefits of growing native varieties in their landscapes and with a simple technique called cold stratification, you can easily add these wildflowers to your garden in the spring.
Cold Stratify Seeds: Why Not Just Sow The Seed?
Many annual varieties, like Zinnias, and Sunflowers, have soft shells and can simply be sprinkled on bare soil in the spring. But some perennials, especially native wildflowers, have a hard coating that helps protect the outer shell from breaking and sprouting too early. We’ve all experienced an unseasonably-warm spell in in the middle of January or February — this mechanism helps prevent the seeds from being tricked into coming out of dormancy until it’s just the right time.
The good news for gardeners is that the natural cold stratification needed for germination can be forced with just a few materials, water, a refrigerator, and patience.
If you’re planting native wildflowers or varieties that require cold stratification in the fall, this step isn’t necessary. Nature will do what it does best during the winter months and cold stratify the seeds for you.
There are quite a few native varieties that should be cold stratified before planted in spring. We chose Prairie Violet Seeds, St. John’s Wort, and Tennessee Purple Coneflower as some of our varieties to plant.
Cold Stratify Seeds: Varieties
There are several perennial and native seed varieties need to be manually broken from dormancy in order to sprout and thrive in your garden. If you’re planting native seeds and aren’t sure, chances are you should at least scarify and soak your seeds before planting.
Learn how to scarify and soak seeds for spring planting.
Common varieties that require cold stratification for spring planting:
- Milkweed (Asclepias)
- Lupine (Lupinus)
- St. John’s Wort (Hypericum perforatum)
- Prairie Coneflower (Ratibida)
- Prairie Violet (Viola pedatifida)
- Pincushion Flower (Scabiosa)
- Marsh Marigold (Caltha palustris)
- Perennial Sunflowers (Helianthus)
- Wild Geranium (Geranium maculatum)
- Rudbeckia (most varieties)
- Coneflower (some varieties)
- Soapwort (Saponaria ocymoides)
- Primrose (Oenothera speciosa)
- Larkspur (Delphinium)
- Shooting Star (Dodecatheon meadia)
- Lavender/Hyssop (Agastache foeniculum)
- Catmint (nepeta)
- Ironweed (Vernonia gigantea)
Although this is a comprehensive list of the most common varieties, there are other seeds that do require cold stratification before spring planting. It’s best to call us at (877) 309-7333 if you aren’t sure.
Most of the materials you need to cold stratify seeds can be found in your home or tool shed.
Cold Stratify Seeds: Gather Materials
Cold stratification is an extremely easy process and once you’ve done it once, you’ll no doubt get the hang of it. The first step is to gather the materials needed, all of which can be found in your home, tool shed, or with a quick trip to the hardware store.
Materials for Cold Stratification:
- An all purpose sand mixture and/or Peat Moss
- Paper Towels
- Plastic ziploc bags
- A Sharpie or pen for labeling
- Mixing bowls
Cold Stratify Seeds: Step by Step Process
Now that you have your materials, you can use three different methods for cold stratifying your seeds. All three of these methods work equally well and offer up different ways to basically keep the seeds moist in your refrigerator until it’s time to plant. We’ll go over all three methods:
- Place a 1/4 cup of sand (or more) in a mixing bowl. Slowly add water until you can form a ball with the sand/water mixture.
- Add your desired seed amount to the sand. Mix thoroughly.
- Place sand/seed mixture in a ziploc bag and seal.
- Label the variety and date clearly on the bag.
- Place in the refrigerator for 1 month before planting. If seedlings start to sprout in the bag in the refrigerator, remove immediately and either plant in the ground or in pots until it’s time to plant outdoors.
Cold stratification is a plant defense mechanism, designed to keep seeds from breaking dormancy and sprouting at the wrong time. In nature, seeds would cold stratify all on their own under a blanket of snow. Starting seeds for your garden in the spring is a different matter, as those seeds have likely been in a warm, room temperature packet all winter long. No worries, it’s easy enough to stratify seeds at home before planting.
I spend a lot of the winter months here in Vermont flipping through garden catalogs and dreaming of my spring garden. They’re full of beautiful pictures and text designed to convince you to grow just about everything under the sun. The problem is, when those little seed packets arrive there’s often an extra step before planting: Cold Stratification.
I’ve been caught off guard by the need to cold stratify seeds more than once, and now I look over the planting instructions on every single packet as soon as they arrive. The catalogs always gloss over the technical details of growing particular crops, but the seed packets are a wealth of information. Take a look at the packets, and they’ll say something like “Stratify seeds for 6 weeks before planting” or “seeds require 5 days cold, moist stratification to break dormancy.”
The amount of time will depend on the crop, but for the most part, the process of stratifying seeds is the same.
How to Stratify seeds
The most dependable way to stratify seeds is in a moist medium, wrapped in plastic in the refrigerator. Larger seeds tend to do well in a bit of moistened peat or sand, placed into a plastic bag. Smaller seeds can be distributed onto moist paper towels. The trick is to keep them moist, but not sopping wet.
The bag itself is designed to retain moisture, but like all living things, the seeds need to breathe. Ensure adequate ventilation during cold stratification by cracking the top of the bag open, or punching a few small holes into the bag. I generally use Ziploc storage bags, and I just don’t seal the top.
Some instructions will tell you to moisten the medium with a bit of water and hydrogen peroxide, and the added peroxide will sterilize the medium a bit and prevent mold. I haven’t found this necessary, and if you find yourself battling mold consider adding less water to the towels, increasing ventilation or moving them to a colder spot in the fridge (I keep them at the way back).
How Long to Cold Stratify Seeds
The length of time to cold stratify seeds really depends on the variety. I’ve seen packets labeled “cold stratify for 5 days” and I wonder, what’s the point? But that plant evolved that response for a reason and the times I’ve ignored it they don’t sprout. Most plants that require stratification need a bit longer than that, usually at least 4 to 6 weeks.
As a general rule, the hardier the plant, the longer they need to cold stratify. Sea Buckthorn, a very hardy Siberian superfruit that we grow here on our homestead requires 90 days of cold moist stratification. It’s hardy down to zone 2, and it’s hard to find a corner of the earth too cold for this resilient plant.
They’re a bit tricky beyond the cold stratification, as this plant also requires scarification to germinate. That’s another plant defense mechanism, designed to keep seeds that fall from the mother plant from germinating and overcrowding. The seeds will only sprout if they’re beaten up a bit, as though they’ve gone through a bird’s acidic digestive system as they were carried far away from the parent plant. You can accomplish this by rubbing them between 2 sheets of coarse sandpaper to rough them up a bit BEFORE cold stratification.
Scarifying sea buckthorn seed on sandpaper before cold stratification
Growing apples from seed, on the other hand, is a bit simpler. They generally grow from zones 4 to 7/8 and most varieties require about 6 weeks of cold stratification. Actually just storing the apples in the refrigerator often does the trick, and if you’re buying apples late in the winter they’ve likely already spent weeks in cold storage before they hit the grocery store shelves.
On occasion, I’ve even cut into apples that had seeds already sprouting inside as a result of long cold moist stratification more or less by accident in cold storage. For the most part though, if you place apple seeds on moist paper towels in the fridge they’ll start to germinate right around the 6-week mark.
Growing apples from seed ~ They require about 6 weeks of cold stratification to germinate.
Lazy Seed Stratification
While most plants respond well to cold, moist stratification using sand, peat or paper towels…others are less picky. Cold dry stratification works well with some varieties, and that basically means just sticking the whole seed packet in the back of the refrigerator.
I’ve had pretty good success with this method in the past few years, as two toddlers running around means I have A LOT less time to futz around with the pickiest of plants. When those surprise packets arrive with the words “cold stratify” on the outside, I just stick them right in the fridge and it’s worked out pretty well thus far.
We have a huge bumper crop of marshmallow plants as a result of that lazy method, no paper towels required.
Marshmallow plants require 3-4 weeks cold stratification, but they’re not fussy. Just stick the seed packet in the refrigerator about a month before planting.
Cold Stratification In the Garden
Another very simple method for cold stratification is to simply plant the seeds outdoors late in the fall. This mimics nature’s natural rhythms, and it’s like the plants just dropped their seed heads at the end of the season. The seeds will overwinter under a blanket of snow, staying just the right temperature for germination.
A couple of things to keep in mind with this method though…
- The seeds are outdoors, and could just as easily be eaten by moles, chipmunks or birds. That’s one reason to plant them as late in the fall as possible, to minimize the time they’re out there before snow cover protects them (somewhat).
- This only works if you’re in the right growing zone. Chokecherries, for example, will grow as bushes as warm as zone 8. The seeds, however, won’t cold stratify in that climate. They’ll only grow from seed outdoors in cooler climates, below zone 6. If you’re in a warm climate, keep in mind you may need to artificially stratify seeds.
Chokecherry fruits ~ While the plants will grow as warm as zone 8, the seeds require a longer cold stratification and they won’t self-seed above zone 6. In that case, the only option is artificial cold stratification.
Seeds that Don’t Require Cold Stratification
When I learned about cold stratification, I assumed that most plants, especially perennials, grown in our cold northern climate would require cold stratification. Not the case. When I was researching how to grow rhubarb from seed I was pleasantly surprised that it doesn’t require cold stratification.
That was great news, as it was spring already and those seeds had been stored all winter in my pantry…
I also learned that it’s actually grown as an annual in hot climates (zone 9/10) by direct seeding fresh seeds in the fall, and growing the cold-loving plants in a hot climate winter. More good news, since my family loves rhubarb and lives in the Mojave desert!
Rhubarb is a plant that I assumed would require cold stratification, but in reality, it doesn’t require any cold seed storage at all for good germination.
Similarly, you can grow strawberries from seed without any cold stratification. It just goes to show you that there’s really no telling what’s going to require cold stratification. As a rule, many but not all, native plants from cold climates will require cold stratification. Good examples include common milkweed, St. Johns Wort, coneflowers, and rudbeckia.
See, that seed packet surprise didn’t turn out so bad after all! You learned a few new things about your plants and got to participate in a time-honored winter ritual that the plants have been enduring year after year as a part of their natural cycle of life. Isn’t it neat that this time it happened right in your own fridge?
It’s not always so simple as just sticking seeds in the ground. There are a number of techniques and treatments that encourage seeds to germinate. We’ve all soaked wrinkled-skinned pea and other big seeds to help loosen those skins and make water absorption easier. Or we’ve nicked hard skin seeds with a sharp blade or even a fingernail (scarification) for the same purpose.
Then there’s stratification, the act of simulating winter conditions — cold and moist — to prep seeds for their usual germination temperatures come spring. This can involve placing them in the refrigerator, usually in some kind of moist potting soil. Or it can mean storing seeds outside during winter in a sealed plastic bag or covered container, again with grow mix.
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Seeds that benefit from stratification are often small and tiny perennials. Delphinium and violets, even when started indoors, have higher germination rates after stratification. Lettuce seed, which goes dormant at higher temperatures, takes to stratification. Some tree seed, including maple, walnut, and apple, require some kind of stratification.
Many perennial herb seeds do better after getting the cold, stratification treatment.
Kevin Jacobs over at A Garden for the House, has a long list of perennials that benefit from seed stratification.
Consider tiny ornamental poppy seed. They benefit from a chill period before planting. Blend seed and mix in a 1:3 ratio in a plastic bag or a small container like a margarine tub and put them in your refrigerator.
Keep them refrigerated for several weeks before planting in the garden. Three months is not too long if the soil mix isn’t too moist. Don’t be afraid to pull them out of the refrigerator every once in a while to check their condition. If you only have a couple weeks before planting, that’s still going to give you better germination rates that no stratification at all.
Seeds can also be stored outside if your winter is cold enough. Use the 1:3, seed-to-mix ratio and be sure to seal bags and containers tightly to prevent them from drying out. Putting the containers away from the harshest conditions, including wind and direct sunlight, will help keep the seed from drying out. Often the north side of a house or garage, out of the wind, is a good choice.
Don’t be afraid to put them out when it’s good and cold in January and December and leave them until just before planting. You might bury the packets under some mulch, or even move them into an unheated shed, if you expect an extreme cold snap. Again, check them for moisture as is convenient.
Of course, sometimes it is as simple as just sticking seeds in the ground. We’ve had surprising spring germination of greens, including bok choy, using natural stratification, planting the seeds in the late fall or early winter at proper depth and mulching with hay.
We suspected that our shredded leaf mulch might have kept one fall-planted kale patch too moist one year, allowing the seeds to rot during a thaw. But as always other factors might have been involved as well. Seeds planted outdoors in autumn can fall prey to many problems, including hungry mice. They might be safer in the refrigerator.
It’s only January! Surely it’s too soon to sow seeds? Source: worldartsme.com, rdkate.blogspot.ca & mzayat. com
The new year has barely begun, yet now and over the coming month it’s already time to start certain seeds indoors.
This is a very select group of especially slow-to-mature plants. January is far too early for most seeds (think March or April instead), but you need about four to five months of indoor culture to bring the following plants to the right state of growth for outdoor planting.
- Agastache (Agastache foeniculum)
- Datura (Datura metel)
- Fairy Snapdragon (Chaenorrhinum origanifolium, syn. glaerosum)
- Lisianthus (Eustoma grandiflora)
- Spike dracaena or cabbage palm (Cordyline australis, syn. indivisa)
- Tritome (Kniphofia )
- Tuberous Begonia (Begonia × tuberhybrida)
No Easy Feat!
Artificial light is almost essential for seeds started in January. Source: laidbackgardener. blog
Starting seed in January in the Northern Hemisphere is not simple. The days are short, the sun is weak and, in many areas, the weather is gray more often than sunny, meaning light is seriously lacking. Also, temperatures in front of the average windowsill are cool, yet almost all seeds need warmth—and fairly even temperatures—to germinate well. As a result, you pretty much have to start these under artificial lights, such as fluorescent or LED plant lights, and in the warmest part of your home.
Germinate the seedlings under glass, possibly over a heating pad, as above. Source: www.amazon.fr
Always start winter-sown seeds “under glass” (under some sort of transparent covering) to maintain high humidity and stable temperatures and in a room that is at least moderately warm (72 to 75˚ F/21 to 24˚ C) or place the seed containers on a heating pad (one specifically designed for plants). Use a timer to set the day length of your lamp at 14 hours to simulate the long days of summer and place the containers of freshly sown seeds about 6 to 12 inches (15 to 30 cm) below the lamp. Now, wait patiently for germination to occur. (One reason that certain seeds need early sowing is that they are slow to germinate.)
Seeds That Require a Cold Treatment
Many tree, shrub and perennial seeds need a cold treatment before they will germinate. Source: laidbackgardener. blog
January (or December or February) is also a good time to start seeds that need a cold treatment (cold stratification) to germinate well. This group includes most trees and shrubs from cold and temperate climates, but also many perennials and even a few annuals.
These seeds will not germinate until they have received a given number of days of cool, moist conditions, from as little as one or two weeks to four months or more, information you would (hopefully) find on the seed pack.
The number of weeks given is the minimum requirement for that species, but there is no maximum. So, if you keep seeds that need, say, a two-week treatment in the cold for two months, that’s not a problem. That’s nice to know, because the information on the minimum cold treatment for seed X is not always available, especially for seed you harvested yourself. If you don’t know, I suggest giving seeds of perennials a six to eight-week cold treatment: that’s usually enough. For trees and shrubs, I’d recommend three months.
Simply sow these seeds in a container as you would any other, then seal them inside a clear plastic bag and pop them into the refrigerator or cold room for at least the minimum number of weeks. Afterwards, move them to a warm, well-lit spot, on a windowsill or under lights, for germination to start.
100 Seeds That Need a Cold Treatment
Here are 100 plants that germinate best with a cold treatment (there are thousands of others!). Check the seed envelope or the seed supplier’s web site for more information.
Seed dormancy sounds rather appealing right now. I’d like to wrap myself up in a warm coat and spend the next few months in stasis until spring arrives. If only that was what really happens. It may seem as if seeds are just lying in the soil waiting for the temperature to rise, but something else is going on.
For many seeds, dormancy is broken not by a rise in temperature but by a drop. It’s the cold of winter these seeds are after. The season’s cycle of frost, harsh winds and bitter rains slowly softens the tough seed coat, rolling it around in the soil, freezing and then thawing again, until the seed can take up water and germinate. This is known as stratification, or cold treatment. You can tell seeds that need a cold period before germinating because they have hard bony coats that are impervious to water.
Having such a tough shell ensures that germination occurs only when conditions are right. Weather fluctuates; you don’t want your seed jumping into germination just because autumn has a few cold nights and then a warm one. It’s not spring yet and those cold nights did not represent winter. So time and temperature are the keys necessary to unlock germination for many seeds. For others it may be light, smoke, certain chemicals or spending time in an animal’s gut.
Many domesticated plants have undergone numerous selection pressures, so dormancy isn’t such a big deal. Wild plants, however, are fiercely dedicated to their dormancy methods. Common plants that require stratification include apples, sloes, hawthorns, plums and acorns, but also smaller seed from herbaceous perennials such as aquilegia, lavender, sage, sedums, perennial sweet peas, wild rose and hops.
One way to break this dormancy is to leave it up to nature. This is not the fast route, but it’s a sure one. Sow seeds outside now in pots, cover with grit (mostly so that it’s easy to weed out any interlopers) and leave them to the elements. Be patient: signs of life should appear, if not this spring, then the following. You can also make a seed bed for stratification. Use a gritty compost mix, one part grit to three parts compost. Excess moisture can be a problem, so make sure it is free-draining.
Or cheat. You can use the fridge (and sometimes the freezer), placing the seed either on a damp sheet of kitchen towel or in damp vermiculite in a freezer bag (on which you can write all the details: seed source, date, temperature requirements etc). Most seed that requires a winter chill will need between two weeks and three months before dormancy is broken. Keep checking the seeds until you see signs of life. Once they germinate, take them out of the fridge, pot them up and keep them frost-free until you can put them outside.
Germinating Perennial Seeds
Perennial Seeds May Need a Winter – Dormancy
Seeds of many perennials do not germinate as easily as annuals. Perennial seeds often contain germination inhibitors, abscisic acid, dormin, waxes and other oils. This is nature’s way of ensuring seeds germinate when conditions are optimal. Annual plant seeds generally have a shallow dormancy and do not need a winter to germinate, they only live one season. The techniques below are for perennial seeds only, do not use these techniques on annual or bi-annual plant seeds.
In the wild, dormancy is broken by spending time in the ground through the winter so that its hard seed coat is softened by frost and weathering. This cold moist period triggers the seed’s embryo to grow and eventually break though the softened seed coat in its search for the sun and nutrients.
In all cases below use well-drained weed-free seed starting or potting soils. See our wiki Potting Soils: Customizing to a Plant’s Needs.
If you are still having trouble after trying one of these techniques, order more seeds and try other methods. It has taking us 4-5 years to get good at starting some difficult varieties such as Good King Henry, Black Cohosh, Balm of Gilead, Sea Kale or Arnica chamissonis. In some cases we have to sow 10-20 seeds to get one plant. Once established you can start harvesting your own seed or multiply by division such as Black Cohosh.
Some seeds require scratching or nicking the hard seed coat to allow moisture to enter the seed to begin germination. This mimics natures weathering, freezing and thawing, or the gnawing of rodents. Medium to larger seeds can be nicked with a knife, filed or rubbed with sandpaper. Test whether a seed needs scarification or not by soaking in water overnight. If swells up, it is imbibing water and probably does not need scarification.
Rub smaller seeds between sandpaper or emery paper. Hobby rock tumblers can be used to scarify larger seed volumes. Abrade only the outer coating, embryos should not be cracked or damaged to remain viable. Commercial nurseries scarify using solutions of sulfuric acid. Do not scarify on the hilum attachment scar.
We do not recommend hot water scarification. This method can greatly damage your seeds by burning them and rendering them non-viable.
Some seeds have a double dormancy requiring both scarification first followed by cold stratification. Others such as Black Cohosh require both warm and cold stratification. See a varieties’ growing instructions for its scarification and stratification requirements.
Cold stratification is the exposure of seed to conditions of cold temperature for germination to begin. The range of cold temperature or vernalization required varies from one crop to another. In general, an optimum temperature for most crops is between 33˚F to 40˚F for at least 8 weeks. Each of our seed packets and online listings should state the desired cold stratification period in weeks. Do not freeze seeds unless you are certain that they contain less than 10 percent moisture.
Here are six methods of stratification. Try different methods. Buy multiple packets of difficult to germinate seeds. Split your seeds between different methods, start dates or cold stratification lengths. Label name and start date with a lead pencil.
Seed requires the recommended treatment only once. For example, do not cold stratify and then fall sow. This is a double cold stratification. Once the initial stratification is complete the seed is ready to germinate. Should there be a fall warm up, the seed will begin the process of germination and may be killed by the freezing temperatures of winter. In addition, once the seed has completed stratification, it is ready to start growing. In this state the seed will use up its energy reserves at a rapid rate and will have a much reduced shelf life at warmer or cooler temperatures.
Seed should be stored cold prior to sowing or stratifying. Allow the seed to warm to room temperature, then soak in water 12–14 hours, for most species. Seed must be moist not wet to stratify. Most seeds are dried to below 10 percent moisture for best storage. Seed below 10 percent moisture does not stratify well and may just sit dormant. The moisture level must be increased to 60 percent or more to allow the seed to begin to stratify. Cold stratify in damp vermiculite in a refrigerator during December and January. Experienced growers like vermiculite because it washes off the seeds easier. For small seeds like Arnica, put them in a bag with a damp, but not wet, paper towel that does not contain bleach. Avoid fine sand because it is harder to work with. Sow in plug flats or undivided trays in the greenhouse when seeds comes out of the refrigerator. Read packet instructions to see if bottom heat is required, for most it is not. Reminder to keep the seeds damp, not wet so they do not rot.
2. Outdoor Treatment
Sometimes refrigeration does not work for various reasons such as seeds just need to be frozen hard or more biology in involved to break dormancy. This method mimics natural freeze-thaw stratification. Mother Nature will naturally cold stratify seed over the winter for seeds planted outside in colder areas. Sow seeds in well-drained starting soil mix. Place the flats on the North side of your house or in full shade. Be sure seeds are protected from rodents, birds and cats. We cover our flats with weighted 1/4″ or 1/2″ hardware cloth. One advantage of this method is that young seedlings do not have to compete with weeds as they get started and can be planted out when more mature. If you purchase your seeds after mid-March, in Zone 7 or warmer, do not use this method because you may need more cold winter evening temperature days than are left in the season. If you have a dry winter, place pieces of 1/4″ ice or 1/2″ snow on the flats to melt every few days, not a lot, just enough to keep some moisture on the flats.
3. Fall Sowing
Direct sowing in the garden or pots in the Fall is the traditional method in Europe. Sow in sterile potting mix if your soil has many weed seeds. This method naturally exposes perennial seeds to winter conditions. Be sure to stake where you sow and date. Wood popsicle sticks fade and rot over the winter. Use larger stakes, plastic stakes written with a black Sharpie last the longest. Plant at a depth appropriate for the variety. Seeds requiring light to germinate, just press on the surface.
4. Winter Solstice Sowing
A variation of Fall sowing is planting later in the winter starting with the Winter Solstice on up to February. This method takes full advantage of winter cold and spring heaving and the growing energy of the earth as days lengthen. This works well for hard to start seeds like Good King Henry, we direct sow once in each month from November through March to find the right stratification window. In our zone 7b, mid-December was the proper sowing time to germinate Good King Henry.
Direct sow in place or sow in well drained flats. Some cover their flats with plastic with holes or screens to let snow. Make this a part of your annual Winter Solstice celebration. You can soak medium to larger seeds overnight to aid germination. If seeds do not require light to germinate, sprinkle with dry soil to cover per sowing depth on the seed packet.
The colder your winter the later you can plant. If you have cold winters and it is very cold out, 30˚F (0˚F), put your seeds in the fridge for two weeks before sowing outside to reduce the shock.
5. Snow Planting
This one is for the kids. After a heavy snow, go outside and broadcast your seeds on the snow where you want them to grown preferably over a prepared garden bed. Have a snowball fight or toss snow over the seeds so birds do not eat them all. This method works best for varieties that can handle cold but do not require cold stratification such as hardy annuals, biennials or short lived perennials.
6. Cold Water Soaking
This method works best for medium and larger seeds a few weeks before last frost. You are trying to imitate snowmelt. Place seeds in a small jar and fill with cold water. Viable seeds should sink, although this is not true for all seeds. Many flat seeds or seeds with edges float. Change water daily, your are trying to wash germination inhibitors in the seed. Sow after two weeks. You can also try putting seeds in a small muslin bag and suspending them in the toilet tank. What could be easier, automatic rinsing. If the seeds do not swell when soaked in water, they may need scarification to allow water to imbibe through their water tight covering.
When a seed requires both a warm and cold stratification, the warm stratification is done first, followed by the cold stratification. A warm stratification is done to soften the seed coat or allow the seed embryo to mature. Warm stratification is at the temperature of 68-86 degrees F˚.
Light Dependent Germination – Surface Sowing
Light dependency is controlled by a protein pigment called ‘phytochrome’ that resides in the seed coat. The survival advantage allows seeds to bide their time until they emerge into light and have the right conditions to develop into a mature plant. Usually required for very tiny seeds such as mullein and St. John’s wort.
Mix tiny seed with tablespoon of fine sand to help prevent germinating in clumps. Water small seeds from below or light misting. Violent watering may dislodge the seed at the critical time and result in germination failure. Seedlings grown in flats should be potted up and grown out for several months until they reach sufficient size to transplant.
If direct sown seeds dry out in your climate from sun or wind and do not require light to germinate, keep moist by covering with a single layer of burlap, light colored cotton sheet or half an inch of loose grass clippings. Remove burlap or sheet after germination. Shading with a window screen or white row cover above them the first season will help prevent drying in hot climates. You can also cover with clear plastic until germination to retain moisture but be very careful not to overheat. As soon as sprouts appear, remove covering.
Although not dead, some seed resists imbibing water and remain dormant even when sown in optimal conditions. As much as 70 percent of seeds may not germinate. Hard seed may be waiting for a variety of conditions to germinate, heat dependence, light dependence, temperature variation, expansion and contraction, time after an initial flush of germination, passage of several seasons or the presence of gibberellic acid. Gibberellic GA3 acid is a germination stimulanting hormone produced in the seed when it imbibes water but not all plants can produce their own and require it in the soil. Gibberellic acid is released when fungi break down and is not present in sterile potting mixes. See our wiki Potting Soils: Customizing to a Plant’s Needs about how to make your own live potting soil mixes.
Early Bottom Heat Germination
Starting tomatoes and peppers in January or February in the greenhouse sometimes requires a little more effort than in mid-April. These crops must be subject to continuous warm soil temperatures, 70-85˚F is optimal for tomatoes, peppers and yerba mansa. However, nighttime temperatures early on can be so cold that despite using a heat mat your surface soil temperature may be below 60˚F. Try doubling up on the heat mats to keep soil temperatures warm at night. Cover flats with a clear acrylic domes in the evenings. If you are having very cold temperatures add a row cover or second dome at night. Keep an eye on them so you do not solarize your starts during the day. Never cover your flats with clear plastic.
Invest in a soil thermometer to see exactly what your actual surface soil temperature is vs. what the heat mat controller may be set at. Some controllers can control up to four heat mats. If your tomato germination is slow, this may be the problem. We also place our tomato plug flats in a leak-proof tray filled with 1/2-3/4″ of water to keep the environment moist.
Deep Potting Soil for Perennials
Perennial seeds requiring several months or even years to develop normally before transplanting out require deeper soil beds than provided by plug trays designed for annuals. Annuals develop quickly and are ready to plant out in a matter of weeks. Fill a gallon pot(s) with good potting soil, sprinkle the seeds on top, barely cover, tamp securely and keep evenly moist and in the light until germination occurs. Plant the whole packet because sometimes only a small portion of the seed will germinate on the first flush. Thin by transplanting to dedicated pots after the second real leaves develop. Hold on to the original pots and subject to outdoor winter conditions if you can after transplanting and see if more seeds germinate the following season.
Sow perennials seeds in sterile potting soil. Keep seeds moist but do not over water. Do not sow in peat moss or Perlite. See our blog, Making Your Own Potting Soil.
Tamping and Misting
Tamping gives the seeds a sense of place. If they shift after they have sent out their rootlet, a more delicate seed may not be able to reorient and be exhausted. Mist seed flats instead of spraying to prevent moving the seed around until starts are well established even if required two or three times per day. Do not allow water to pool over the seeds, it should drain quickly in good potting soil.
Good growing from Restoration Seeds.
Seed Germination Theory and Practice by Norman C. Deno, 1993-1994.
The Organic Seed Grower by John Navazio.
Seed to Seed by Suzanne Ashworth, 2002.
Starting From Seed: The Natural Gardener’s Guide to Propagating Plants, Brooklyn Botanical Garden, 2000.
Plant Propagation, The American Horticultural Society, 1999.
The Medicinal Herb Grower, Volume I by Richo Cech, 2009.
© 2012-2018 Restoration Seeds, LLC
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- What is Permaculture?
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- Sowing Calendar and Companion Planting Guide
A modified version of fall planting is to plant later in the year, from Winter Solstice (December 21) all the way up through February, depending on the severity of your winters. The harder your winter, the later you can plant. This takes advantage not only of the natural swings between cold and warm that occur in late winter but of the growth energy of the Earth that starts once the days begin to lengthen at Solstice. So this method combines temperature fluctuation with snowmelt and increasing daylength to help seeds grow. Europeans have been winter sowing for decades–I’ve seen a mosaic from Roman times depicting Frenchemn winter sowing beans–so it was not invented by an American. Americans simply tend to use throw-away containers instead of terra cotta or plastic pots, and to use the plastic tops instead of screens or glass. By the way, don’t waste your time planting annuals in the winter. It will just stress them, and a lot of them will die or be knocked out by late frosts. Annuals will germinate just fine planted in the spring.Top
You can incorporate planting into your Yule celebration or just do it as a private affirmation that even on the darkest day of the year, even in the very deepest of sleep, the Earth is getting ready to awaken. If you are in the Southern Hemisphere, this same method will work on Summer Solstice. Top
Any covered container works – including terra cotta pots, as described in fall planting section. The kind of foil and plastic-topped baking pans you can find in the supermarket in the baking aisle are convenient (although at a dollar a pop, not cheap). Regular little 25-slot planting trays that come with a plastic cover work well and are not expensive if you get them on sale in the late summer at garden centers. You can use any sort of plastic carry-out food containers with a plastic lid as long as the bottom part is deep enough–at least an inch. Top
For drainage, make some slits in the bottom of the pan or tray with a knife or poke holes with the tip of a Philips screwdriver. Fill the pan with seed starting soil (or use jiffy pellets) and tamp down gently. Don’t use dirt from the yard, as it is usually compacted, which makes it hard for some seeds to break through. Water well before sowing–until it is mudpie consistency (this is the way you want to start out, not the way you want it to stay permanently). If your planting mix has got any peat moss in it, it will get wet more easily with warm water–just make sure if you use hot to let it cool off before you put the seeds in. Top
When the soil has drained, take the seeds you’ve had soaking overnight and toss out any floaters. Pour the rest into your hand, letting the water drain through your fingers, and sprinkle them *thinly* on top. If the seeds are very small, like wormwood seeds, you don’t need to soak them overnight. If you plant the seeds too thickly, you will end up with spindly seedlings that will tend to die from damping off. It’s a good idea to sow at most only half of a packet at a time. Try other methods of sowing with the rest of the seeds so you can figure out which method works best for you, for your seeds, and for your climate. I have noticed that everyone has their own best way to plant. Top
Gently pat the seeds down with your hand. You want a good contact between soil and seed. Then sprinkle a thin layer of soil (some use sand or grit) over the seeds, barely covering them, and gently pat that down as well. You don’t need that covering soil to be wet–it sprinkles more easily if it is dry, and it will wet quickly from the soil beneath it. If the seeds are very tiny, like for wormwood or other dust-like seeds, don’t cover them with any extra soil, just very gently pat them in (trying not to let them get stuck to your hand!). Top
Make slits in the plastic cover or plastic wrap, or just use a piece of screen so heat and air can get in and out, or seeds will cook in the sun even in winter. Put the lid on and fold the foil pan edges around it so it is secure and can’t be blown off or removed by hungry critters. Don’t forget to label the pan with the seed name(s)–I can’t tell you how many times I have forgotten to label plantings and had to wait until they got big before I could figure them out! You can write with a grease pencil (Sharpies fade in the sun) on the pan bottom or even the plastic cover, or use regular address labels on the side. Cover the labels with tape to help keep them dry. I usually print out my labels on my laser printer, which uses waterproof ink, and they stay pretty readable, considering. Top
If it is very cold out, below 30F/0C, condition your seeds for a week or two in your fridge before putting them outside. This will decrease the shock of going from room temperature to below freezing. Top
Put your containers outside in a safe place. On the ground next to the north or east side of the house is best (next to a building should give you at least another zone’s worth of protection). It is good if snow can get on the pans and melt, because the snowmelt can help trigger germination. They should not be in standing water or right in the drip line under the eaves of the house. Too much water, especially in winter, will kill the seeds. If it snows and does not cover them, pile snow over their tops or move them to a sheltered place where snow will cover them–snow’s an important part of this process. Top
Alternately, you can use regular pots and just put them into a plastic baggie, which Deno described in 1993. Then put the whole shebang against the north side of the house. Open the baggie some when the seeds start to germinate, and gradually allow them more light and air. Be careful not to cook them. This method does not make use of snowmelt. It is especially aimed at seeds that like to get a little colder, like aconites. Top
Seeds should germinate in late winter. They won’t come up all at the same time, like the seeds of most cultivated plants are bred to do. Seeds that use cold to germinate are closer to the wild and so have a good reason to stagger their germination – more are likely to survive that way, and you will get more genetic variation. That means there will be a greater likelihood of getting plants that will survive and prosper in your conditions. Top
Once they come up, check them regularly to see if they have enough water. Make sure to put the lids back on securely, because even warm wind can quickly kill seedlings. Each week make the slits in the lid larger, gradually “hardening off” the seedlings so they will be ready to pot up or put them in the ground after they have their first set of true leaves (this is the second pair of leaves they will get). Transplant before they hit the lid or just remove it, if it’s warm enough. Transplanting is best done on a cloudy day so that the sun doesn’t bake the seedlings. Seedlings are just like children and should be treated gently but firmly. Top
How To Grow Lavender From Seed
Lavender is one of the most popular herbs and it has been a garden favorite for many centuries. A hedge of lavender in full bloom is delightful to see and you can grow your own lavender hedge for remarkably cheap if you grow the lavender from seed.
Lavender seed has been available for several years, but until recently, the lavender plants that came from one packet were variable in height and vigor. Growing lavender from newer seeds has overcome this problem and you can now expect a consistent number of plants that look the same which is ideal for a lavender hedge.
Types of Lavender
Lavender Lady was one of the first lavenders that came from seed easily, and it blooms well the first year. Traditional Provence and Lacy Frill, a pretty white lavender, also come from seed and unless you only want one or two plants. Growing lavender from seed is a great way to fill your perennial bed with refreshing fragrance and beautiful color.
Learn About Growing Lavender
Start the seed early and place the seed tray on a heat mat or in a warm location so that your lavender seeds germinate well. Rather than a traditional potting mix, use a very light mix or fine vermiculite that drains very quickly. The seedlings will germinate in about two weeks and will take a while to look like lavender. Make sure that the lavender seedlings get sufficient water, but do not let them stay damp, and place them in full sunlight for maximum health.
When your little lavenders have several sets of leaves on them, put them into their final location, but check them regularly to make sure they have not been knocked over by animals, or dislodged by rain. Once the lavenders are settled in the ground they will grow slowly the first year, but most of them will bloom, and by next year you will have a splendid supply of lavender to plant into a hedge or use as a colorful border for your perennial bed.
Growing Lavender in Containers
Learn more about growing lavender or browse seeds and plants from the link below.