- Planting and Storing Flower Bulbs
- PLANTING BULBS
- Timing Spring Bulb Planting
- Planting Tulips
- Allium Flowers Bring Star Power to the Garden
- Dwarf Iris Planting Guide
- Choosing a Planting Site
- Soil Prep for Dwarf Irises
- When to Plant Dwarf Irises
- How to Plant Dwarf Iris Bulbs
- During the Spring Growing Season
- At Season’s End
- Forcing Bulbs & Pre-Chilled Bulbs
- Insider Tips
- Zone 6 Bulb Gardening: Tips On Growing Bulbs In Zone 6 Gardens
- Zone 6 Bulb Gardening
- Growing Bulbs in Zone 6 Gardens
Planting and Storing Flower Bulbs
WHEN TO PLANT BULBS
Zones 4 to 7: In colder climates, spring bulbs can be planted as soon as the ground is cool, evening temperatures average 40° to 50°F, and it is at least 6 to 8 weeks before the ground freezes. If timed right, this should be as soon as possible after purchase. However, bulbs can be stored in the refrigerator if needed until planting. (See Helpful Hints below for more information on storing bulbs in the refrigerator.) Summer bulbs should be planted in mid to late spring.
Zones 8 to 10: In warmer climates, spring bulbs will need to be chilled in the refrigerator for 6 to 10 weeks (depending on the bulb) until the ground cools enough for planting. (See Helpful Hints below for more information on storing bulbs in the refrigerator.) Summer bulbs can be planted early to mid-spring.
Average planting times for spring bulbs:
- September to October — Zones 4 and 5
- October to early November — Zones 6 and 7
- November to early December — Zones 8 and 9
- Late December to early January — Zone 10
Average planting times for summer bulbs:
- Late March to May — Zones 8 to 10
- May to June — Zones 4 to 7
WHERE TO PLANT BULBS
As long as you ensure that your bulbs have good drainage and sunlight, you can plant them just about anywhere. Drainage is critical to keep bulbs from rotting. They like loamy or slightly sandy soil because it provides the drainage and nutrients they need. Early-spring bloomers can be planted under deciduous trees where they’ll get enough sun to bloom before the tree’s leaves block it out. However, they’ll only bloom well the first year, as they’ll need sunlight later for the leaves to gather enough energy for the next year’s bloom.
PLAN BEFORE YOU PLANT
Bulbs can be grown in many ways — formal gardens, meadow gardens, scattered in lawns, under trees, or strategically planted throughout beds and borders. Many bulbs will naturalize in an area and multiply, coming back year after year, so plan carefully and you can have years of enjoyment from one planting.
- Plant in clusters for greater visual impact.
- Take into account bloom time — plant a combination of early, mid- and late-season bloomers to extend the season.
- Hide dying foliage of low-growing bulbs that are past their prime with taller bulbs planted in front or with companion plants.
- Layer plant heights from front to back when planting varieties that will bloom at the same time.
- Many bulbs are perfect for container planting — bring them into view when blooming and move out of the way when foliage is wilting and when dormant. Plant closer together in containers than specified for in-ground planting.
- Bulbs can provide bright, vibrant color — think about how those colors will blend with their surroundings.
- Companion plants keep the planting area going when bulbs are dormant. Some good perennial companions are sedum, coreopsis, thyme, cranesbill, daylilies, coral bells, brunnera, hosta, hellebores, or bleeding heart.
HOW TO PLANT BULBS
Bulbs can be planted in layers by digging up an entire area down to the proper depth, placing the bulbs and covering; or in individual holes dug for each bulb. Individual planting is made easier with a specialized bulb-planting tool or a bedding plant auger.
Photo by: KaliAntye / .
- Determine the planting depth for the type of bulb you’re planting. Depth is important for bulbs. If planted too deep, they will bloom late or not at all. If planted too shallow, new growth may become exposed too soon and risk damage by cold temperatures. If you are unsure of the exact planting depth, a good general rule of thumb is to plant the bulb 2 to 3 times as deep as the bulb is tall.
- Prepare the soil by loosening and mixing in organic material if needed for added nutrients or to improve drainage. Special bulb fertilizer can be added; follow the package directions.
- Place the bulbs with the pointy-end up and with the roots down. If you’re not sure of the top or bottom of the bulb, plant it on its side and it will find its way to the surface.
- Cover with soil and a light layer of mulch.
- Newly planted bulbs should be watered well to get settled in.
- If needed, protect bulbs from critters by staking down wire mesh or chicken wire over the beds or planting them in bulb baskets or wire cages.
Not only good for Sunday dinner, lasagna (planting) is great for bulbs. The idea is to plant bulbs with different sizes and staggered bloom times in layers for a continual bloom. This works great in large containers that are deep and wide enough. Here’s a sample plan, working from the bottom up in a container:
Planting a Layered Bulb Pot
- A good layer of potting soil for a planting depth of about 8 inches
- A few late-spring-blooming bulbs such as daffodils or tulips
- Another layer of potting soil for a planting depth of about 6 inches
- Add mid-spring-blooming bulbs such as more tulips or hyacinth
- Another layer of potting soil for a planting depth of about 4 inches
- Add early-blooming bulbs such as galanthus, scilla, muscari or crocus
- Another layer of potting soil for a planting depth of about 2 inches
- Add more early-blooming bulbs such as freesia or anemones
- Top with more potting soil and a thin layer of mulch
- Overplant with pansies, heuchera, hardy cyclamen or dusty miller if you’d like a filler while waiting for the bulbs to grow.
This planting method can be used in-ground as well for a concentrated area planting. It can also be adjusted to fewer layers in smaller pots.
Zone 1 Early September
Zone 2 Early September
Zone 3 September
Zone 4 Late September to early October
Zone 5 Late September to early October
Zone 6 Mid October
Zone 7 Early November
Zone 8 Early November
Zone 9 Early December
Zone 10 Mid December
These guidelines are usually pretty safe to plan on planting spring flowering bulbs, but the arrival of winter in the northern and Midwest zones is unpredictable. So be mindful of these details to adjust your planting plans:
Spring blooming bulbs must be established before beginning their required cold, dormancy. Roots will quickly develop from the bottom, and a little later stems will sprout from the tops. (Spring blooming bulbs for zones 9 & 10 do not require a cold period.)
Avoid, if possible, planting when there is still good possibility of a long enough warm spell for the stems to sprout from the soil. If air and soil temperatures are cold enough, the stem sprout will grow only until just below the surface and stop when the soil temperature is further reduced by freezing temperatures.
Spring bulbs can be planted once night temperatures are consistently between 40 and 50 degrees F, but before the first hard frost. The soil will be cool enough for optimal rooting.
Bulbs should be planted about six weeks before the ground freezes. Bulbs that have had enough time to root will also have gone through a natural process that prevents them from freezing.
After the ground freezes apply 2 – 4 inches of mulch to maintain a more consistent soil temperature. The mulch will also prevent rapid thaw/freeze cycles in early spring, which can heave your bulbs up out of the ground. If your region experiences climate extremes or rapid changes, such as around the Great Lakes or the Northern zones 1 – 3, you may want to choose later blooming bulbs that may not be affected by late freezes.
Planting Summer Blooming Bulbs
Timing Spring Bulb Planting
While it may seem strange, spring-flowering bulbs need to be planted in fall in order to bloom come show time. The bulbs need a certain amount of time to get established before winter’s freezing weather sets in, and they need enough time exposed to cool soil temperatures to be properly chilled. But fall doesn’t occur at the same time on the calendar in San Antonio, Texas, as it does in Minneapolis, Minnesota. So how do you know whether to plant in September or November?
Tools and Materials
- Mulch (hay, straw, or shredded leaves)
- USDA Climate Hardiness Zone map
USDA hardiness zone map. The simplest solution is to use the USDA Climate Hardiness Zone Map as your planting guide. This map breaks the country into 11 growing zones based on average annual winter minimum temperatures. First use the map to find which hardiness zone you live in. Then follow the table below to know when to plant spring-flowering bulbs in your zone.
Hardiness Zone Average Annual Winter Minimum Temperature When to Plant
Zone 1 below -50oF Early September
Zone 2 -50 to -40oF Early September
Zone 3 -40 to -30oF September
Zone 4 -30 to -20oF Late September to early October
Zone 5 -20 to -10oF Late September to early October
Zone 6 -10 to 0oF Mid-October
Zone 7 0 to 10oF Early November
Zone 8 10 to 20oF Early November
Zone 9* 20 to 30oF Early December
Zone 10* 30 to 40oF Mid-December
Zone 11* Above 40oF Late December
* Additional chilling may be needed to grow spring-flowering bulbs in these regions.
Special planting considerations. In coldest areas (USDA Climate Hardiness Zones 1 through 4), bulbs grow and perform best if planted early enough (September) to get established before the ground freezes. Mulch the bed a month after planting with a 3- to 4-inch layer of hay, straw, or shredded leaves. This will allow the soil to stay warm enough for the bulb roots to get established and will protect tender bulbs from freezing injury during winter, especially if the snow cover is sparse.
Bulbs in warm areas. In warmest-winter areas (zones 7 through 11), select bulb varieties that are best adapted to warm winters, such as wild tulips that are native to southern Europe. Most large-flowered tulips, hyacinths, and crocus will need supplemental chilling. To chill the bulbs before planting, place them in the refrigerator crisper for 8 to 10 weeks (but keep bulbs away from fruits or vegetables; they give off ethylene gas, which can cause the bud inside a bulb to abort), then plant. Since the ground rarely freezes deeply, if at all, in these areas, bulbs can be planted into December or even early January.
Even within a given climate zone, fall temperatures can vary widely from year to year. A good rule of thumb is to plant spring-flowering bulbs when the soil temperature 6 inches below the surface is below 60° F.
Bulbs that were not planted in fall at the proper time can be forced indoors this winter (see how-to project on forcing paper whites) or, if the ground still isn’t frozen, planted in the garden. Depending on the severity of the winter, bulbs planted out late in the season may not flower the following spring.
All flowers are beautiful in their own way. But no other flowers herald spring like tulips, which captured the imagination of the Dutch some 400 years ago and can still steal the show today.
Tools and Materials
- High-quality tulip bulbs (in mild-winter areas, chill for six to eight weeks)
- Trowel or bulb-planting tool
- Bulb fertilizer
Quality bulbs. Start with quality bulbs, most often from a mail-order supplier but also from a well-stocked garden center. The Netherlands tightly regulates its tulip growers, and as a consequence, all Dutch tulips are of good quality.
If you’re shopping at a garden center, shop early in the season and choose only bulbs that are firm and free of defects such as cuts, bruises, or mold. Later in the season, be wary of store-bought bulbs or ones offered at significant discount. We also recommend you buy tulips by variety or species name, not color. “Red tulips” for instance, can mean different kinds of varying performance. Or you may get a mixture of colors.
Mild-winter tulips. If you live where winters rarely or never reach freezing temperatures, tulips likely won’t grow all that well. However, you can still grow tulips if you chill them for six to eight weeks before planting (see below). The best choices are Darwin Hybrids or Single Late varieties. The long, strong stems of these tulips are more tolerant of wind and rain, and their midseason blooms appear before hot weather or spring weather.
Species tulips. Or consider some of the species tulips that are better suited to milder climates. These include lady or candy tulip (Tulipa clusiana), with rosy red petals that are white inside; Candia tulip (T. saxatilis), with vivid rose-lilac petals and a yellow base; and yellow Florentine (T. sylvestris). These are smaller and less dramatic than hybrid tulips but are still full of tulip character.
When and where to plant. Plant tulips any time the soil 6 inches deep is 60? F or colder. As a general guide, plant in September or early October in USDA Climate Hardiness Zones 4 and 5; October to early November in zones 6 and 7; November to early December in zones 8 and 9; and late December to early January in zone 10.
Bulbs in warm areas. In zones 8 through 10, refrigerate tulip bulbs for six to eight weeks before planting. Place them in a paper bag away from ripening fruits (the fruits produce ethylene gas, which destroys the flower bud within the bulb).
How to plant. Tulips grow best in full sun in well-prepared soil with fast drainage. Avoid planting where water collects, or in locations that are prone to late frosts.
The rule is to plant tulips pointed end up and 6 inches deep, meaning 4 inches of soil above the top of the bulb. Plant a little deeper, to 8 inches, if soil is light or sandy, or if pests such as voles are a problem. Those 2 extra inches put them just out of reach of voles. Deep planting also keeps the bulbs cooler, an advantage in mild-winter areas.
For an attractive flower display, plant five tulips per square foot, or 250 bulbs per 50 square feet. Space individual bulbs about 5 inches apart. Use a low-nitrogen granular fertilizer specially formulated for bulbs, and follow label directions about the amount to apply
When planting a grouping, take the extra care to plant at exactly the same depth; this ensures that they all will bloom at the same time. With a shovel, excavate soil to create a level planting base. Set bulbs into the bed, fertilize, and then cover with excavated soil.
After planting, firm soil and water thoroughly. Don’t water again until leaves appear. In cold-winter areas (zones 3 through 6), apply straw mulch about a month after planting. This gives the bulbs time to begin growth before the soil freezes solidly. The mulch also protects the bulbs if snow cover is light or nonexistent. In mild-winter areas, mulch after planting to help keep soil as cool as possible for as long as possible.
Combine tulips with perennials to maximize the impact of both. For instance, combine ‘Beauty of Apeldoorn’ tulip with basket-of-gold (Aurinia saxatilis). Or combine any tulip with white candytuft (Iberis sempervirens).
Photography by Suzanne DeJohn/National Gardening Association
Every year I receive lots of questions regarding tulips, daffodils, hyacinths and other spring flowering bulbs. Most of these questions either come in the spring when these garden beauties are in bloom, or mid-fall when gardeners are trying to get them planted.
This year I thought it would be helpful to get ahead of the game and answer 10 of the most frequently asked questions now, before the fall rush.
1. How can I prevent squirrels and rodents from eating my bulbs?
Planting bulbs in fall for spring bloom can be a bit of a chore, even if the results are well worth the effort. I’ve come up with a way to make the job a little easier and prevent four legged visitors from disturbing all my hard work.
Bulbs should be planted at a depth that is 3 times their height. For example, if a daffodil bulb is approximately 2 inches tall, dig a hole 6 inches deep. And remember that if you plan to add mulch, factor it in to your planting depth.
Rather than dig individual holes for each bulb I dig out the entire area that I want to plant. I dig it to the required depth of the largest bulb. If I have smaller bulbs I create little mounds of soil for them to sit on that will bring them up to the proper planting depth. I place my bulbs in the dug out area with the pointed end up and the flatter, usually larger end sitting at the bottom of the bed. I then add my bulb food and refill the area with soil. I use a synthetic bulb food because it is less attractive to animals than bone meal, another commonly used fertilizer.
This is the point where I add a piece of chicken wire to further prevent squirrels, raccoons and other neighborhood creatures from getting to the bulbs. I simply cut a piece of chicken wire 1 inch larger on each side than the size of bulb bed. I bend the edges to create a shallow box top shape and set the chicken wire on top of my newly planted bulbs. I then push the 1 inch edges down into the soil. To complete the planting I add a 2 to 3 inch layer of mulch. Now this does 3 things. It hides the chicken wire, further insulates the bulbs and gives the beds a finished look.
In the spring when the bulb foliage begins to emerge, I’ll remove the chicken wire so that the plants can grow freely.
2. When should I plant spring flowering bulbs?
Spring flowering bulbs can be planted anytime in the fall before the ground freezes. They must be planted in the fall rather than in the spring because they require a long period of cool temperatures to spark their growth process that causes them to flower. In cold climates (zones 1 – 4) this can be done as early as late August or September, while in more temperate areas (zones 4 – 7) planting can be done any time between September and November.
For best results, plant bulbs as soon as possible after you purchase them. Your bulbs need to establish strong root systems, before the frosts of winter set in and the bulbs enter a new cycle in preparation for spring blooming.
3. Why don’t tulips come back year after year?
A frequent misconception about tulips is that they don’t come back year after year. Actually, tulips are perennial in their native environment in central Asia. In American gardens, tulips don’t come back with the same vigor because the foliage dies back too soon, particularly in the South. It’s this foliage that reinvigorates the bulbs; without the foliage dying back naturally, there’s little chance of the tulip coming back.
In northern gardens, there is a greater chance for tulips to be perennial because the spring is cooler and longer, but even in the north you need to plant a few bulbs each fall to keep the display as effective and beautiful as it can be.
You should also know that there are some varieties that are more reliably perennial than others. Both species tulips and Darwin hybrids are known to return. The darker hued Darwin hybrids do better than the pastel ones.
To encourage tulips to come back plant them in an area that gets good drainage and plant them deep, about 8 inches from the bottom of the bulb to the top of the soil. Fertilize in the fall and spring. After the blooms have faded remove the spent flowers and allow the foliage to die back naturally. This helps the bulbs store up energy for next year’s bloom.
In my zone 7 garden I grow the species tulip T. clusiana ‘Lady Jane’ and it has reappeared in the spring for several years now. But the modern hybrid tulip should be treated as an annual in southern gardens. You have to plant it each year, but the blooms are so beautiful, it is still worthwhile.
4. I live in a warm, zone 9 climate. Can I still plant spring flowering bulbs?
It is a bit more challenging to grow spring flowering bulbs in a warm climate because the winters don’t give the bulbs the chilling required to bloom, but, if you take special measures, you can still add their beauty to your garden.
First, with the exception of the daffodils and narcissus, you need to cool your bulbs in the refrigerator for about 6 weeks.
Place bulbs in a ventilated bag (best choices: paper bags, mesh bulb bags, or new open weave vegetable baggies) in a refrigerator at the usual fridge temperature of 40° F to 45° F for a minimum of six to eight weeks. Don’t worry if you bought the bulbs early in the season and need to store them for several months before planting: keep them chilling – even up to 12 to 16 weeks if necessary, until it is time to plant.
Remove any fruit (especially apples) in the refrigerator, for the ethylene gas given off by all ripening fruit will kill the flower inside bulbs.
Keep bulbs in the refrigerator until planting. Take them directly from the fridge to your planting site.
Water the garden after planting to help the establish root growth. If you live in a dry area, be sure to water the garden about once a week.
5. How should I store my bulbs until I am ready to plant them?
I often get into a situation where I can’t get my bulbs planted as soon as I would like. In such instances I keep the bulbs in a cool, dry place, such as my garage, or basement. Warmth and moisture will signal the bulbs to start growing. I check on them occasionally to be sure they aren’t getting moldy or soft and plant them as soon as I can.
6. What should I do with the foliage after the blooms have faded in the spring?
Well if you are dealing with perennial bulbs such as daffodils and want flowers next year you should treat the foliage with respect. It actually restores the bulb’s energy through photosynthesis and helps the bulb prepare for blooming next year, so don’t cut it back. It’s okay to remove the spent flower but be sure to leave the stem intact.
After a while the foliage may begin to look a little rough but keep it in place for at least 8 weeks after the flower fades or until the foliage withers and dies back.
One solution to camouflaging the fading foliage is to over plant your bulbs with cool season annuals such as pansies or even perennials, which will emerge and begin to gain height about the time the foliage is beginning to appear unsightly.
This is also an excellent time to feed your bulbs. I just use about a tablespoon or so of a well-balanced fertilizer like 20-20-20 or triple 13 and sprinkle it around the base of the plants.
7. When can I transplant daffodils?
If you have daffodils that are in need of relocating, spring is a good time to transplant them. Because the foliage is visible you will have no trouble seeing them in the ground. Just remember the name of the game here is to keep the leaves green as long as possible to recharge the bulb for next year’s flower. For the best results, wait about 8 weeks after the blooms have faded to move your daffodils. When you do move them, take care not to do damage to the bulb, and make sure that the bulb and foliage stay intact.
8. Are there any deer resistant spring flowering bulbs?
Believe it or not there are a few plants that deer tend to pass by. I’ve had the most success with daffodils, but alliums, crocus, chinodoxa, scilla, grape hyacinths and snow drops are all supposed to be deer resistant. But what I’ve found is that if deer get hungry enough, they’ll eat anything, even these varieties. About the only full proof system is a very tall fence or a dog trained to keep deer away.
9. What do recommend planting in addition to the standard tulips and daffodils?
I must confess that the bulbs I plant the most of are tulips. I guess I just love the classic bloom and wide range of colors available. However, for variety there are some other, less typical bulbs that I plant every year as well.
Allium schubertii – Large, spidery blooms comprised of purple star-shaped florets. These are great planted in drifts and make an elegant statement as a single cut flower in a vase.
Anemone blanda – I have to say that I don’t actually grow this bulb, but have always appreciated its simple daisy-like bloom. They are great for forcing to enjoy indoors. I like the ‘Blue Shades’ variety because, well, I like blue.
Arum italicum – This is really a three season plant. Good for gardens in zones 5 – 9, it produces mottled arrow shaped foliage in the winter, chartreuse ‘Jack-in-the-pulpit’ like blooms in the spring and bright red berries in summer.
Camassia leichtlinii ‘Blue Danube’ – This North American native plant produces tall spikes of blue star shaped flowers in late spring or early summer.
Eremurus -The plume shaped blooms are similar to a foxtail giving it the common name of foxtail lily. The stature of this plant makes a statement. Depending on the variety it can grow up to 7 feet tall.
Leucojum aestivum ‘Gravetye Giant’ – The white bell-shaped flowers of this plant are edged with a chartreuse green. I like this variety because the blooms are larger than other leucojums.
10. What bulbs are good for forcing to enjoy indoors?
The easiest spring flowering bulbs for forcing are amaryllis, paperwhites, hyacinths, muscari and large flowering crocus. Other bulbs that can be forced but may require a little more attention are tulips, miniature daffodils, lily-of-the-valley and freesias.
Allium Flowers Bring Star Power to the Garden
Stylish, long-lived and easy to grow, alliums are unbeatable bulbs for the perennial border By Jenny Andrews
With names like ‘gladiator’, ‘goliath’ and ‘globemaster’, there’s no doubt about the powerful punch alliums can pack. Also called ornamental onions, their sparkling flowers are arranged in symmetrical globes—egg, baseball or soccer-ball size—dramatically perched on leafless stalks, or in a delicate, pendulous clutch. While most alliums are purplish-pink, they also come in white-glove white (Allium ‘Mount Everest’), cornflower blue (A. caeruleum) and butter yellow (A. moly). Close cousins to popular and pungent onions and garlic, they even deter deer. Alliums can be grown from seed, but hybrids won’t come true and you may end up waiting a year or more for them to bloom. Allium bulbs planted in the fall will flower just as spring bloomers are winding down and continue until summer bloomers kick into gear. They also make chic pairings with a plethora of other perennials and even lend a touch of humor.
Photo by: Rob Cardillo.
Both beautiful and edible, chives are at home in the border or the kitchen. Clumps of grassy, tubular, tasty leaves are topped by tufty heads of pinkish-purple flowers. Popular with pollinators, but not with mammal pests like deer. Summer blooming and nearly evergreen. Zone 5.
Photo by: Rob Cardillo.
Volleyball-size heads of silvery amethyst burst into bloom in summer on two-foot stalks – startling, sculptural and sparkling. Star of Persia adds drama when emerging through lowgrowing perennials. Flower heads dry well, like fireworks frozen in time. Zone 5.
Photo by: Rob Cardillo.
A. ‘MOUNT EVEREST’ — Buy now on Amazon
A tall hybrid with frosty-white, six-inch snowballs of flowers perched on ramrod-straight, three-foot stalks in late spring to early summer. Low-growing foliage doesn’t die back during flowering, making a green groundcover under the blooms. Zone 4.
Photo by: Rob Cardillo.
West Coast native with loose, half-dollar-size clusters of lavender-pink flowers, blooming May to July on foot-tall stalks. Though misleadingly named one-leaf onion, each bulb produces two to three leaves. Found in the wild in grasslands that are damp during the spring, this allium is more moisture tolerant than most. Be prepared for it to spread and naturalize. Zone 5.
Photo by: John Scheepers.
A. SPHAEROCEPHALON — Buy now on Amazon
Claret-colored, golf-ball-size clusters of flowers, tightly packed and egg-shaped, nod and sway kinetically atop thin two- to three-foot stalks in late summer. Drumstick allium makes a good companion for shorter perennials, or as a see-through front of the border plant. Zone 4.
Photo by: Rob Cardillo.
A . HOLLANDICUM ‘PURPLE SENSATION’ — Buy now on Amazon
Hundreds of purplish flowers are packed into perfect baseball size globes, blooming from late spring to early summer. A classic ornamental onion. Sturdy stems are two to three feet tall. Straplike leaves conveniently disappear as flowering begins. A great cut flower, it can last three weeks in a vase. Zone 4.
Photo by: Rob Cardillo.
Dainty nodding onion (sometimes called lady’s leek) is a summer-blooming North American wildflower, native to dry open woods and meadows. The flower stalks, a foot tall or more, have a distinctive crook at the end, so the one- to two-inch umbels of pale pink or white flowers hang downward. Leaf blades are slender and flattened rather than tubular, forming a soft grassy clump. Zone 5.
Photo by: Rob Cardillo.
Brilliant azure blue, half-dollar-size flower heads perch on sturdy one to two foot stems — a rare color for alliums and great in combination with yellow and pink. Blooms in June and July. A native of Asia, blue globe onion is an heirloom bulb, introduced in 1830. Naturalizes in the garden in a welcome, not weedy, way. Zone 5.
Appeal: In alliums we find killer combinations of qualities — easy and gorgeous, elegant and playful, dainty and bold, at home in both meadows and formal borders. Perfect “tuck-ins,” alliums play well with other plants, and are reliably perennial. With lots of colors, heights and sizes, there are alliums for every garden, small or large. They also make outstanding, long-lasting cut flowers.
Zones: Ornamental onions can be grown all across the United States, from hardiness zones as low as 3 to as high as 8, depending on the variety.
Exposure: Most alliums prefer full sun – even part shade will make them lean over, reaching for the light. But a few species, such as nodding onion, garlic chives and Allium karataviense can take a bit of shade.
Soil: Alliums are generally tolerant as to soil type. The important thing to remember with alliums, as with most bulbs, is to avoid wet locations, especially during their dormant period. A winter of cold and damp will lead to rotting and woe. Whether it’s gravelly or loamy, soil absolutely must be well-drained for alliums to survive and thrive.
Care: Ornamental onions are one of the most carefree of perennials, virtually pest-free. The inherent compounds (sulfides) that make some species culinary favorites with humans ironically make all alliums distasteful to deer and other garden nibblers. Plant in the fall, twice as deep as the bulb is tall, with the pointy end up. Allow foliage to die back naturally; don’t cut it off while still green since it feeds the bulbs and sets them up for a successful flower display the following year. To avoid seeing fading bulb foliage, plant alliums among perennials that require similar conditions.
For more on how to plant bulbs: Bulbs 101: Planting and Storing Bulbs
DESIGNING WITH ALLIUMS:
- Alliums make great “mixers” among other border plants, and many can be planted to come up through lower-growing perennials like Nepeta x faassenii and Geranium sanguineum, which also hide fading bulb foliage.
- Since alliums are perennial, they can be integral elements in a longterm design that gets better as it matures. The consistency of height and flower-cluster size in a single species make alliums a perfect plant for repetition in the garden.
- Ornamental onions offer a variety of heights, colors and bloom times, so you can sprinkle a lot of different types throughout the garden. They can also serve as bridge plants, helping the garden transition from spring into summer.
- The combination of long stems and spherical flower clusters, swaying and nodding in the breeze, adds three-dimensionality to the garden. Plant with sturdy architectural plants like Phlomis and tall sedums for textural counterpoint.
- Combine alliums with grasses such as fountain grass and herbs like lavender for a deer-resistant garden.
Dwarf Iris Planting Guide
Tiny, but mighty, dwarf irises add pops of color, intricate patterns and accents with bright yellow or gold blazes, speckled and spotted. These short beauties are perfect for edging the walk by the front door or adding some color to the patio border where you’ll enjoy that first early season lunch outdoors in the sunshine.
Choosing a Planting Site
Choose a site with full to half day sun. Since dwarf irises actively grow in the spring and then slip into dormancy by May, areas near/under open-branched or limbed up deciduous trees can work beautifully. These spots are often sunny and perfect early in the spring, before the trees are fully leafed out. In warmer regions, a little protection from afternoon sun will extend the blooming window.
Soil Prep for Dwarf Irises
Look for a site that drains well. Irises are happy in average garden soil, and as with most bulbs, good drainage is important to avoid bulb rot. If your soil is heavy (clay or compacted) consider digging in a few generous handfuls of soil amendments such as a mix of course sand and compost, leaf mold or well-rotten manure. (Your local cooperative extension office can recommend good mixes that are appropriate for your local soil conditions.) A slow release granular fertilizer (10-10-10) mixed into the planting soil according to package directions can be helpful if you soil is lean. Note: we do not recommend using bone meal as it encourages pets and pests to dig up the bulbs you just planted.
When to Plant Dwarf Irises
Plant these bulbs in mid to late autumn or into early winter in mild regions, when soil in your area has started to cool. The roots on these iris bulbs start to develop in the fall and continue to grow, albeit more slowly, when soils are quite chilly but not yet frozen.
These bulbs should not be held over for spring planting as they need to develop a network of roots before spring sprouting begins.
How to Plant Dwarf Iris Bulbs
Dig holes 4-5” deep and add a handful or two of compost to the soil you removed. Plant your irises so the bulb base is 3” to 4” below the soil line. Put the bulb in the hole with the pointed end facing up, fill the hole with soil, pat to eliminate air pockets, and water well to settle the soil around the bulb. While there won’t be any visible growth in the fall, the bulbs’ roots will be growing and creating a network for absorbing nutrients and moisture.
Because of their size, dwarf iris look best grouped, typically in clusters of about 6 per square foot.
During the Spring Growing Season
Dwarf irises need about one inch of water a week from rain, irrigation or a combination of the two.
When spring flowering has finished, don’t remove the leaves; they’re working to produce food for the bulbs. Allow the foliage ripen until it yellows before removing it.
At Season’s End
After flowering, your iris foliage will photosynthesize and create food for next year’s show. Then the bulbs will go dormant and sleep through the summer. They don’t need, or benefit from, any extra moisture during the summer. When fall temperatures cool, the bulbs will develop new roots and then wait for spring rains and warmth to prompt the next cycle of growth and blooms.
Forcing Bulbs & Pre-Chilled Bulbs
Planning to force your bulbs or plant pre-chilled bulbs in winter? Read this! Forcing Bulbs & Pre-Chilled Bulbs
- Plant dwarf iris bulbs at a rate of about 6 per square foot. These are petite plants and they looks best clustered together.
- Site your dwarf iris patch(es) where you’ll be able to enjoy the incredible patterns and detail on the colorful petals.
- Over time, dwarf irises naturalize and spread gently into ever larger patches. Site with this in mind.
- For gardeners in zone 4, mulching with 2 inches of shredded leaves or leaf mold will help your irises overwinter more readily.
- If you live in a warm part of the country, where spring arrives early, make sure to plant your outdoor irises by late November to give the bulbs time to root in. Otherwise, they may begin to sprout before supporting roots have developed.
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Zone 6 Bulb Gardening: Tips On Growing Bulbs In Zone 6 Gardens
Zone 6, being a milder climate, gives gardeners the opportunity to grow a wide variety of plants. Many cold climate plants, as well as some warmer climate plants, will grow well here. This is also true for zone 6 bulb gardening. While winter in zone 6 is still too cold for tropical bulbs like calla lily, dahliaand cannato remain in ground, zone 6 summers provide them with a longer growing season than gardens in the north. Cold hardy bulbs such as tulip, daffodiland hyacinthappreciate the cool winters this zone provides. Read on for more information about growing bulbs in zone 6.
Zone 6 Bulb Gardening
Many types of hardy bulbs require a cold dormant period in winter. While winters are still cold enough in zone 6 to provide this dormancy period, gardeners in warmer climates may have to simulate this cold period for certain bulbs. Below is a list of some of the cold hardy bulbs that perform well in zone 6. These bulbs are usually planted in fall, require at least several weeks of a cold, and oftentimes naturalize in the garden:
- Asiatic Lily
- Blackberry Lily
- Foxtail Lily
- Glory of the Snow
- Lily of the Valley
- Oriental Lily
- Spring Starflower
- Surprise Lily
- Winter Aconite
Some bulbs that cannot survive northern winters but grow well in zone 6 are listed below:
- Chinese Ground Orchid
Growing Bulbs in Zone 6 Gardens
When growing bulbs in zone 6, one of the most important necessities is a well-draining site. Bulbs are prone to rots and other fungal diseases in soggy soils. It’s also important to think about companion and succession planting with bulbs.
Many bulbs bloom for only a short time, oftentimes in spring, then they slowly die back to the ground, absorbing the nutrients from their dying foliage for bulb growth. Perennials or shrubs that fill in and bloom once your bulbs are finished can help hide the unsightly, wilting foliage of spring blooming bulbs.