How to winter dahlias?

How to overwinter dahlia tubers

There are two ways of overwintering dahlias, and which you choose depends on what role you want them to play in your garden.

In mild winters dahlias can be left in the ground, but to be avoid losing them you can easily lift them and bring them indoors.

Overwintering dahlias in single beds

If, like me, you grow dahlias for cutting in big beds, you can leave them in the ground over winter.

Mulch your dahlias in late autumn under several inches of mushroom compost or similar and just clear this away once the worst of the frosts are over in the spring. Overwintering dahlias like this means you do not need to lift the tubers.

Overwintering dahlias in a mixed bed

If you grow dahlias for late summer and autumn colour in a mixed border, you’re probably best lifting them. Pip Morrison (a great friend and garden designer who introduced me to Dahlia ‘Admiral Rawlings’), advises you are best to lift them as winter begins. Overwintering dahlias left in their beds will become overshadowed by spring and summer growth.

In an intensive and colourful bed, you also want to showcase earlier performers, such as a teepee of sweet peas or a big drift of a tall, impressive annual bedding plant like the invaluable Ammi majus. Dahlias can be slotted in to replace these, but in these circumstances, lifting it must be.

To be sure of conserving your plants for next year, dig them up after the tops have been frosted once or twice in the autumn. Cut them down to 15cm (6in) before you do so. Knock off the surplus soil and, with a small piece of stick, scoop out the loose soil between the tubers – but leave enough to hold them in place. Do not clean the tubers under a tap; to get water on a tuber at this time of year often spells disaster. Let them dry, hanging upside down from a dried stalk, leaving them there for a couple of weeks. Dust them with Bordeaux Mixture to discourage mould and mildew, then pack them away in a storage box in moist peat or sand. This prevents the tubers drying out. Store them in a cool, frost-free place – a cellar is perfect.

Overwinter your dahlias planted up in big pots – 3 litres or above – so they can grow to a decent size before planting out. Then whatever is flowering in the early summer can perform until the end of June, when the dahlias can go in to replace them, already impressive and almost in flower.

You’ll also need to stake and support all dahlias. Bar the ”container-sized” varieties such as Dahlia ‘Bishop of Oxford’ and Dahlia ‘Roxy’, all the ones I grow need canes and string to hold them up in wind and rain.

You may also like:

  • How to plant and grow dahlia tubers
  • The history of the dahlia
  • Growing dahlias in pots (video)

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I often hear the question: can you leave dahlias in the ground over winter? Of course, this will depend on many factors including: where you live, the severity of the winter, whether your garden is exposed to hard frost, etc. In this article, we will look at ways of preserving your dahlia plants so that you can enjoy them from year to year.

There aren’t many flowers that can surpass the beauty of the less-than-humble Dahlia. Colourful, waxy and butter-scented; they are the must-have addition to any garden. But did you know that you can easily overwinter your Dahlias, so that you can enjoy them next year?

Although Dahlias are perennial, they are also tender. Special care is needed when storing their tubers to protect them from hard frosts.

As the colder months encroach, you may need to dig up your Dahlias tubers and store them in a frost-free environment. However, there are alternatives. More on that later. Firstly, let’s take a look at overwintering our dahlia roots in a frost free environment.

How to overwinter Dahlia tubers

  1. During late October, cut the tops of your dahlia plants to encourage tuber development.
  2. In November, cut the stems of your Dahlias to between 3-6 inches from the ground level. Don’t forget to label the stumps so that you can keep track of each variety.
  3. Dig down to about 8-10 inches deep around each Dahlia plant with a fork. Ensure that you don’t damage the brittle tubers. Once you have loosened the soil, lift them slowly out of the ground. Be gentle! If Dahlia tubers snap during the digging process, they may no longer be viable.
  4. Remove any excess soil or compost from around each tuber.
  5. Remove organic materials such as thin or decaying roots and leaves. This will help prevent fungal infections and other diseases.
  6. Remove the ‘mother root’ or last year’s tuber.
  7. Leave to upside-down for a week to allow the tubers to heal.
  8. The Dahlia tubers must remain dry but not dry out completely.
  9. Place in a dry, frost-free environment.
  10. Evenly space in a tray or box and fill with sawdust, spent dry compost or vermiculite.
  11. Cover with cardboard or add an extra quilt if you live in a colder climate.
  12. Keep an eye on your Dahlia tubers. If they dry out, spray a little water on them with a trigger spray.
  13. Discard any rotten or moulding roots to limit infection.

An alternative to lifting tubers

If you live in a milder part of the UK, then you might want to leave your Dahlias in the ground overwinter. I like this method as it offers very little disruption to the plants. You will need to cover each root-stock with a ‘molehill’ of spent compost. This will act as a blanket against hard frosts. You may also want to try covering your dahlias with fleece, hay or straw to protect them from the worst of the frost. Make sure you feed your Dahlias with fish bone and blood during late spring to encourage vigorous growth and plenty of flowers.

Dahlias – when to plant – UK

Your tubers have survived the winter and now it is time to plant them out again. The following is a description of when to plant your Dahlias if you live in the UK. Times and techniques may vary for other countries.

  1. Carefully place tubers in 2-3 litre pots of free draining, general purpose compost during March to early April.
  2. Cover each Dahlia with compost so that only the stump is visible. Don’t bury deeply. Dahlia tubers grow immediate beneath the soil level.
  3. Place pots in a frost free and bright location.
  4. Water your Dahlias. Don’t over-water, but ensure that the compost doesn’t dry out. Boggy compost will rot your tubers.
  5. After the risk of frost has passed, plant them in a sunny spot, in a fertile and well-drained soil.
  6. Space each Dahlia between 50 cm – 75 cm.
  7. Mulch around your plants with a 3 cm layer of compost. This will help retain moisture and block some weeds from competing with your Dahlias.
  8. Flowering should start in early July.
  9. Dead-head your Dahlias daily.
  10. Enjoy until early December and then overwinter your Dahlias for next year!

If you have enjoyed this guide on how to overwinter Dahlia tubers, perhaps you would like to read our Overwintering Begonias post.

Geoff Hoyle, Dahlia expert

Here is a great video on everything you need to know about getting the best out of your dahlia plants. It is by Geoff Hoyle, a keen Dahlia grower in Bredbury, Cheshire. He not only takes you through planning, planting, staking and propagation, he also explains how to over winter Dahlias in great detail.

Tags:Colourful Flowers, Cottage Garden, Cut Flowers, Long Flowering, Ornamental Garden, Overwintering, Propagation

PLANTING & CARE OF BULBS: DIGGING & STORING

Most Bulbs prefer not to be disturbed and can be left in the ground for many years. But beware of overcrowding. When too many bulbs try to occupy the same space, they will be less vigorous and flowers will be fewer and smaller, an indication that it’s time to transplant them.
Lifting Bulbs
If you lift your Bulbs, they should be stored in a well ventilated place and replanted in the fall. Every five years Daffodils and Crocus should be dug and replanted to prevent overcrowding. The first sign of overcrowding will be a decrease in the flower size, uneven bloom and uneven plant height. When this occurs, dig, spread bulbs out and replant immediately.
Summer – Less hardy bulbs such as Dahlias or Begonias should be lifted each fall. It is best to lift after frost has blackened foliage, gently spade up the bulbs, being careful not to cut into the bulbs/tubers and damage them. If you prefer to lift the bulbs before frost has hit, you can dig your bulbs early and store them in a well-ventilated, frost-free area until they are dry. Just let the leaves remain on the bulbs until they become dry.
Most bulbs should be dried for about a week before you prepare them for storage. Pull any loose any remaining foliage, shake the bulbs gently to remove any clinging soil, dust them with fungicide powder to prevent rot and place them in unsealed paper bags or old nylon stockings with some dry peat moss to keep the bulbs from touching one another. Store them away from sunlight in a cool, dry basement, cellar, garage or shed at 60° to 65°F. Avoid temperatures below 50° or above 70°F unless different instructions are given for a particular bulbs. Follow specific storing instructions for tender bulbs, such as Dahlias,Gladiolus and Begonias.
For more information on lifting and storing dahlias for the winter please see our blog article by clicking here: Lifting and Storing Dahlias in Winter.

Saving Dahlias: How To Remove And Store Dahlia Tubers

Dahlias are a breeder and collector’s dream. They come in such a wide variety of sizes and colors that there is sure to be a form for any gardener. Dahlia tubers are not terribly winter hardy and will rot in the ground in many regions. They split in freezing temperatures and mold in soggy soil. It is best to dig them up and store them indoors for the cold season and then reinstall them in spring.

Tips for Saving Dahlias

There are several ways of storing dahlia tubers for winter. The crucial part of the process is cleaning and drying. However, even the best methods still require you to inspect the tubers occasionally over the course of the winter. Environmental changes in the storage location, such as increased humidity or fluctuating temperatures, can still damage overwintering dahlia tubers.

Whether you have the dinner plate sized bombshells or the dainty lollipop variety, it is important to know how to remove and store dahlia tubers. The plants are perennials in USDA plant hardiness zones 6 to 7 but will succumb in the ground in lower zones. So, your choice in colder climates is to treat them like annuals or dig them up for storage. Dahlia storing only takes a few minutes and a couple of inexpensive materials.

How to Remove and Store Dahlia Tubers

Wait until the foliage has turned yellow before digging up the tubers. This is important so that the plant can gather energy for the following year. It will store starches in the tuber which will fuel initial sprouting in summer.

Cut off the foliage and carefully dig out the tubers. Brush off excess dirt and let the tubers dry for a few days. If possible, hang them upside down when drying them so that moisture can leach out of them.

Drying is important to saving dahlias over winter and preventing them from rotting. However, they do need to keep slightly moist on the interior to keep the embryo alive. Once the skin is wrinkled, the tubers should be dry enough. Once they are dry, they are packed away.

Storing Dahlia Tubers for Winter

Gardeners differ on the best way to pack overwintering dahlia tubers. Some swear by packing them in peat moss or sand in trays in an area about 40 to 45 degrees Fahrenheit (4-7 C.). You may also try storing them in a heavy plastic bag with packing material or even a Styrofoam ice chest. Separate the roots from each other with peat, cedar chips or perlite. In temperate zones where freezes are not sustained, you can store them in a basement or garage in a paper bag.

Some gardeners advise dusting the tubers with a fungicide before packing. Whatever method of dahlia storage you choose, you will need to check the tubers occasionally to ensure they are not rotting. Remove any that might be getting rot to prevent them from affecting all the tubers.

Plant them out again after all danger of frost has passed and enjoy their brilliant tones and flashy forms.

Mark Cullen: What to do with your dahlia tubers this time of year

The frost will have hit the top portion of most dahlias growing in Canada by now and that is not a bad thing. The trick to rescuing them from the demise of frost is to get them out of the ground before the frost enters it. In other words, before the roots freeze.
I wait for the tops of my dahlias to die down with the early fall frost first, as this knocks the plants out and reduces their size in my composting units . Also, I enjoy the flowers until mother Natures spoils them for me with a killing frost – why not? I have waited this long for them.
After you dig the frost damaged plants out of the ground with a garden fork or with a spade, shake of the loose dirt, hose them down with a course spray of water and let them dry in the warm sun for a day or so. Do not let the tubers freeze.
Store them in dry peat moss, shredded newspaper or vermiculite, after you have dusted them with Green Earth garden sulphur.
Use a paper bag to store them: never plastic as it does not ‘breathe.’
And place your tubers in a dark, cool place for the winter. Your basement likely works well, providing that it is not too damp.
Come March, remove them from their storage place, plant them up in 2 gallon containers and place them in a sunny window to grow on of another season.
Easy.
For more details go to www.markcullen.com.

Need help with what to do in your garden?

Dahlias bring beautiful late-summer flowers to our gardens, but they get hot by frost in the autumn. Which? Gardening magazine trialled different overwintering methods to find out which works best:

Caption: Dahlia ‘Bishop of Llandaff’ is just one of the beautiful varieties you can choose from

Lifting dahlia tubers and overwintering indoors

The best way to overwinter dahlias is also the most labour-intensive. We lifted our dahlias tubers, dried them and stored them in a frost-free shed. We potted them up in spring, and kept them in the greenhouse before hardening off and planting them out after they had already put on some growth.
It’s this extra care that makes the difference with dahlias. When planted out, our lifted plants put on the most growth and started flowering earlier than the other methods.

Caption: Lift dahlia tubers when the frost blackens the leaves in autumn

Other methods we tried:

Mulching dahlias

In the mild winter of 16/17, tubers mulched and left in the bed overwintered well in both Glasgow and Yorkshire, although the plants weren’t the tallest in our test by mid-summer. This surprised the Glasgow gardeners, who usually have to dig up and store their tubers, as they rot in the wet, clay soil.

Propagating dahlias

We tried two methods of increasing our stock of dahlias. We divided some tubers into two or three pieces and this worked well. The plants were small and straggly by mid-summer, but soon bulked up, making this an easy way to grow new plants. We also took basal cuttings that were slow to establish and slower to grow than dividing the tubers.

Caption: Dahlia cuttings are slower to grow than dividing dahlia tubers

by Matt Gibson

If you grow dahlias, you’ve likely fallen in love with their impressive blooms, and you won’t be happy about giving up your precious dahlias when chilly weather arrives. The good news is that you don’t have to say goodbye to this season’s dahlias when you learn to remove and store their tubers. It’s time for overwintering. Keep on reading to learn about how to remove tubers from dahlias and store them during the winter so they can make a reappearance in your garden come spring.
Dahlia flowers have become a popular sight to admire in modern flower gardens in Europe and the United States due to their low-maintenance care needs and resilient general nature, not to mention their massive, multi-layered, and magnificent blossoms. Dahlias are perfect for planting directly into your flower beds as well as growing in container gardens. They can be grown successfully in both indoor and outdoor settings. Dahlias’ large, stunning flowers also serve fantastically cut fresh from the garden and added to a vase as the focal point of an arrangement or bouquet.

Dahlias are related to sunflowers and aster flowers and are grown solely for ornamental purposes, as they have no culinary or medicinal value. Like sunflowers, dahlias are known for their massive size and giant flowerheads.

Dahlia plants can reach six feet in height and produce blooms as large as 12 inches in diameter. Dahlia flowers have also earned their reputation among gardeners for adding longlasting beauty because their blooms, once open, will remain stunning for several weeks—whether in the ground or after they have been cut.

Dahlia flowers come in several different types, a variety that offers gardeners just about every color and color combination under the sun, The flowers are so lush and lovely and easy to grow that breeders have taken it upon themselves to create an array of hybrid varieties of the dahlia flower, providing gardeners with a wide selections of choices, with lots of options in various sizes and colors.

Do Dahlias Come Back Year After Year?

Dahlias are tropical flowers, and when they’re grown in warmer climate areas, they tend to survive for several years. Dahlias are not frost hardy, however, so if you don’t live in a tropical climate region, you will need to dig up the tubers and store them indoors over the winter if you want to bring them back the following year. The process of removing and storing the dahlia tubers is not a tough task at all.

Removing Dahlia Tubers and Preparing Them For Winter Storage

If you grew your dahlia flowers in a container, there’s no need to dig up the bulbs to store them indoors as you can simply move the container inside when the temperature starts to dip nearer to frost. First, trim back the foliage to encourage new healthy growth. Next, bring your dahlias indoors and store them in a cool, dry place until spring comes around again.

If you planted your dahlias directly in your garden beds, follow these four steps to store them safely so that you can bring them back next year.

  1. Once the winter weather has killed off the foliage and turned it black and the plant appears dormant, dig up the tubers.
  2. Shake or brush off any excess dirt particles clinging to the tubers, keeping only the dirt needed to keep the clump of tubers intact.
  3. Completely remove any remaining stems and leaves from the tubers.
  4. If the bulbs are small, you can store them immediately. Larger bulbs need to be left out to dry before storing (a process also known as curing). This step is needed to prevent excess moisture from causing tuber contamination, such as fungal and bacterial growth or mildew.

That’s all you need to do to prepare your tubers for winter storage. You should now have a large clump of tubers that are connected to each other by the root system of the original plant. There’s no need to rinse the tubers or to separate them for winter storage. Leave each plant’s tubers in a large clump with a small amount of dirt that helps keep the clump from breaking apart. Once the larger tubers are completely dry to the touch, the clump is ready to store.

Methods of Winter Storage for Dahlia Bulbs

Storing your dahlia tubers is a very simple task, and there are several ways to do it. The easiest way is to simply place the tuber clumps inside of a paper bag. The bag should then be stored in a cool, dark place, such as a cabinet or shelf in the basement of your home. This method is fine for large bulbs, but small dahlia bulbs are in danger of drying out completely during the winter when stored this way, rendering them (and your efforts) useless.

The safest method is a little bit more time consuming but will give your dahlias the best chance of success when you replant them next spring. All you will need is a cardboard box and packing material that’s dry to slightly moist, such as sawdust, pet bedding, peat moss, coconut coir, or a mix of equal parts vermiculite and perlite. Whatever you have on hand or is the least drain on your funds will work fine. Follow these steps to make your own dahlia tuber storage box.

  1. Line the bottom of the box with newspaper topped by a generous layer of packing material.
  2. Now it’s time to put the tubers inside the storage box. If you are only storing one clump of tubers, you may want to add even more packing material to the bottom layer so that the clump will sit near the center of the box and is supported equally on all sides by the packing material. Place the clump in the middle of the box.
  3. If you have a good collection of dahlias, you probably have a lot more than one clump of tubers in need of storage. Storing multiple clumps in one box is perfectly fine, but try to arrange the tuber clumps so that they are not touching one another.
  4. Fill the box with your packing material so that the bulbs are covered completely, then close the box.
  5. House the box of dahlia bulb clumps in a cool, dry location where the temperature level never drops below freezing. Choose with care: If the temperature drops too low, your bulbs could die. If the temperature becomes too warm, your bulbs could rot.

Another storage method that is popular among gardeners is to keep the tubers in trays packed with either peat moss or sand. These trays should be kept in areas that stay around 40-45 degrees Fahrenheit. You can also store trays of tubers in a heavy plastic bag with packing material, such as peat or perlite. If you use a heavy plastic bag, make sure to leave it partially open so that moisture can escape to help avoid mildew and rot.

Whatever you do, don’t store your dahlia tubers in sealed plastic containers. Avoid using light plastic bags, plastic trash receptacles, or plastic bins to store your tubers over the winter. Light plastic containers, especially when sealed, tend to trap excess moisture inside, and dahlia bulbs need to remain cool and dry during the winter months.

A Styrofoam ice chest or any type of Styrofoam container will also serve wonderfully for storing tubers over winter, and you may already have a container you can use. Keep the dahlia roots separated from each other using perlite, peat moss, or cedar chips. Some gardeners suggest using a fungicide to lightly dust the tubers before storing them to prevent fungal infections and to help fend off rotting.

No matter what method of storage you choose or what container you store them in, you will want to keep an eye on your tubers, checking occasionally to be sure that none of them have begun to soften and rot. If you notice signs of rot, remove and discard any rotting tubers immediately so that the problem doesn’t spread and ruin all of your bulbs.

Videos About Growing Dahlia Flowers

If you really want to know the correct way to grow and care for dahlia flowers, the best way to get an advantage is to learn from other gardeners who have experience growing dahlias themselves. The following three videos give you the tips and tricks of three different gardeners who have experience with growing dahlia flowers.

YouTube Gardener Lew Whitney’s Secrets to Growing and Maintaining Dahlias:

YouTube Gardener Shirley Bovshow’s Tips For Growing Dahlias:

YouTube Gardening Duo “The Dahliaholics,” How Geoff and Heather Grow Dahlias:

This short how-to guide teaches you how to easily propagate dahlia flowers from cuttings:

Overwhelmed by the many varieties of the dahlia flower? This video breaks down the different types of dahlias that you can plant to beautify your flower garden:

Once you know what type of blooms you like the best, you can start picking out the specific varieties that you want to grow this season. This slideshow provides 75 different species of dahlia blooms to help you choose when it’s time to order seeds:

Want to Learn More About Growing Dahlia Flowers?

The following link will take you to Gardening Channel’s very own in-depth how-to guide to growing dahlia flowers.

BBOG covers How to Store Dahlias, Cannas, Cladiolo and Other Flower Bulbs Over Winter

Flower Meaning covers Dahlia Flower: Its Meanings & Symbolism

Gardening Know How covers Storing Dahlia Tubers

Get Busy Gardening covers Storing Dahlia Tubers for Winter

The Spruce covers How to Store Dahlia Tubers for Winter

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