Growing Dahlias

How to Plant, Grow, and Care for Dahlias

By Catherine Boeckmann
Perfect Dahlia

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Grow dahlias for gorgeous, colorful flowers that bloom from midsummer through autumn, when many plants are past their best! The tubers are planted in the ground in late spring. In colder zones, you do need to dig up and store the tubers in the fall if you wish to grow them as perennials (or, treat as annuals). Here’s how to plant, grow, and store dahlias.

About Dahlias

Dahlia is a genus of tuberous plants that are members of the Asteraceae family; related species include the sunflower, daisy, chrysanthemum, and zinnia. They grow from small tubers planted in the spring. Picking a favorite dahlia is like going through a button box. As well as coming in a rainbow of colors, dahlia flowers can range in size from petite 2-inch lollipop-style pompoms to giant 15-inch “dinner plate” blooms. Most varieties grow 4 to 5 feet tall.

They are considered a tender perennial in cold regions of North America. They are reliably winter hardy in hardiness zones 8 to 11, though gardeners in zones 6 and 7 may have luck keeping them in the ground as well. In more northern zones, dahlias can either be treated as annuals or dug up and stored indoors for winter. (See what hardiness zone you’re in!)

Dahlias love moist, moderate climates. Though not well suited to extremely hot climates (such as southern Florida or Texas), dahlias brighten up any sunny garden with a growing season that’s at least 120 days long. 

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Planting

When to Plant Dahlias

  • Don’t be in a hurry to plant; dahlias will struggle in cold soil. Ground temperature should reach 60°F. Wait until all danger of spring frost is past before planting. (We plant them a little after the tomato plants go in.)
  • Some gardeners start tubers indoors in containers a month ahead to get a jump on the season. Medium to dwarf-size dahlias will do well in containers.
  • Order dahlia tubers in early spring. This gives gardeners in colder zones time to get them growing in a sunny window. Or, skip the potting and simply plant the tubers in the ground after the spring weather has settled and the soil has warmed.

Choosing and Preparing a Planting Site

  • Select a planting site with full sun. Dahlias grow more blooms with 6 to 8 hours of direct sunlight. They love the morning sunlight best. Choose a location with a bit of protection from the wind.
  • Dahlias thrive in rich, well-drained soil. The pH level of your soil should be 6.5-7.0, slightly acidic.
  • If you have a heavier (clay) soil, add in sand, peat moss, or aged manure to lighten and loosen the soil texture for better drainage. 
  • Large dahlias and those grown solely for cut flowers are best grown in a dedicated plot in rows on their own, free from competition from other plants. Dahlias of medium to low height mix well with other summer flowers. If you only have a vegetable garden, it’s the perfect place to put a row of dahlias for cutting (and something to look at while you’re weeding!).

pink dahlias

How to Plant Dahlias

  • Avoid dahlia tubers that appear wrinkled or rotten. Pink “eyes” (buds) or a little bit of green growth are good signs. Don’t break or cut individual dahlia tubers as you would potatoes.
  • Bedding dahlias can be planted 9 to 12 inches apart. The smaller flowering types, which are usually about 3 feet tall, should be spaced 2 feet apart. The taller, larger-flowered dahlias should be spaced 3 feet apart. If you plant dahlias about 1 foot apart, they make a nice flowering hedge and will support each other.
  • The planting hole should be slightly larger than the root ball of the plant and incorporate some compost or sphagnum peat moss into the soil. It also helps to mix a handful of bonemeal into the planting hole. Otherwise, do not fertilize at planting.
  • Dig a hole that’s about 6 to 8 inches deep. Set the tubers into it, with the growing points, or “eyes,” facing up, and cover with 2 to 3 inches of soil (some say 1 inch is adequate). As the stem sprouts, fill in with soil until it is at ground level.
  • Tall, large-flowered cultivars will require support. Place stakes (five to six feet tall) around plants at planting time and tie stems to them as the plants grow.
  • Dahlias start blooming about 8 weeks after planting, starting in mid-July.
  • Do not water the tubers right after planting; this encourages rot. Wait until the sprouts have appeared above the soil to water.
  • Do not bother mulching the plants. The mulch harbors slugs and dahlias like the sun on their roots.

Check out our video to learn more about growing dahlias in your garden. 

Care

How to Grow Dahlias

Watering

  • There’s no need to water the soil until the dahlia plants appear; in fact, overwatering can cause tubers to rot. After dahlias are established, provide a deep watering 2 to 3 times a week for at least 30 minutes with a sprinkler (and more in dry, hot climates).
  • Like many large-flower hybrid plants, the big dahlias may need extra attention before or after rain, when open blooms tend to fill up with water or take a beating from the wind.

Fertilizing

  • Dahlias benefit from a low-nitrogen liquid fertilizer (similar to what you would use for vegetables) such as a 5-10-10 or 10-20-20. Fertilize after sprouting and then every 3 to 4 weeks from mid-summer until early Autumn. Do NOT overfertilize, especially with nitrogen, or you risk small/no blooms, weak tubers, or rot.

White dahlias

Pinching, Disbudding, and Staking

  • When plants are about 1 foot tall, pinch out 3-4 inches of the growing center branch to encourage bushier plants and to increase stem count and stem length.
  • If you want to grow large flowers try disbudding—removing the 2 smaller buds next to the central one in the flower cluster. This allows the plant to put all of its energy into fewer but considerably larger flowers.
  • Bedding dahlias need no staking or disbudding; simply pinch out the growing point to encourage bushiness, and deadhead as the flowers fade. Pinch the center shoot just above the third set of leaves.
  • For the taller dahlias, insert stakes at planting time. Moderately pinch, disbranch, and disbud, and deadhead to produce a showy display for 3 months or more.

Winter Care

  • Dahlia foliage dies back with the first light frost in fall. In colder regions, the tubers should be dug up before the first hard freeze and stored indoors.
  • Dahlias are reliably hardy in USDA Hardiness Zone 8 and warmer and can simply be cut back and left in the ground to overwinter; cover with a deep, dry mulch. Further north, the tuberous roots should be lifted and stored during the winter. (Some readers find, however, that dahlias will survive in Zone 7 or even Zone 6 if the winter isn’t too severe.)
  • See Harvest/Storage (below) for more information.

Pests/Diseases

  • Slugs and snails: Bait 2 weeks after planting and continue to bait throughout the season.
  • Mites: To avoid spider mites, spray beginning in late July and continue to spray through September. Speak to your garden center about recommended sprays for your area.
  • Earwigs and Cucumber Beetle: They can eat the petals though they do not hurt the plant itself.
  • Aphids
  • Deer: Find a list of deer-resistant plants to grow around your dahlias.
  • Powdery Mildew: This commonly shows up in the fall. You can preventatively spray before this issue arises from late July to August.

Harvest/Storage

Dahlia Bouquets

Dahlias are beautiful in a vase. Plus, the more you cut them the more they will bloom. To gather flowers for a bouquet, cut the stems in the morning before the heat of the day and put them into a bucket with cool water. Remove bottom leaves from the stems and place the dahlias in a vase. Put the vase in a cool spot and check the water daily. The bouquet should last about a week.

Digging and Storing Dahlias for Winter

Unless you live in a warmer region, you have to dig up dahlias in late fall before there is a hard frost in your area. Native to Mexico, Dahlias won’t survive freezing temperatures. Digging and storing dahlias is extremely easy and simple, and will save you the money that would otherwise go into buying new ones each year.

If you live in an area where your ground doesn’t freeze, you don’t need to dig up your tubers. The general rule is: If you live in USDA Hardiness Zone 8 or warmer, you can leave dahlias in the ground. In Zone 6 or colder, dig them up. In Zone 7, you may be able to get away with just covering the plants with a thick layer of leaf or straw mulch, but if a deep freeze hits, you may lose them.

Find your USDA Hardiness Zone here.

When to Dig Up Tubers

Dig up dahlias before the first hard freeze. A light freeze (32°F / 0°C) will kill the foliage, but a hard freeze (28°F / -4°C) will kill the tubers, too. See your fall frost dates.

A good indication of when to dig your tubers up is when the plant starts to turn brown and die back.

How to Dig Up Tubers

Digging up tubers is easy:

  1. After fall frost has killed back the foliage, cut the stems down to 2 to 4 inches.
  2. Carefully dig around tubers with a pitchfork (or shovel) without damaging them.
  3. Lift and gently shake the soil off the tubers.

That’s it! Cut rotten tubers off the clump and leave the clumps outside in the sun upside down to dry naturally.

How to Store Dahlia Tubers

  • Pack in a loose, fluffy material (vermiculite, dry sand, Styrofoam peanuts).
  • Store in a well-ventilated, frost-free place at around 45°F (7°C).

Re-planting Tubers in Spring

  • In the spring, remove the tubers from their storage containers, separate healthy tubers from the parent clump, and plant in the garden. Each tuber must have at least one “eye” or a piece of the crown attached or it will not develop into a blooming plant. The eyes are located at the base of the stem and look like little pink bumps.

See our gardener’s article on how to unpack and divide your stored dahlia tubers!

If this all seems like too much bother or you do not have the right storage place, skip digging and storing, and just start over by buying new tubers in the spring.

Recommended Varieties

There are about 60,000 named varieties and 18 official flower forms including cactus, peony, anemone, stellar, collarette, and waterlily. The American Dahlia Society recognizes 15 different colors and color combinations. Here are some popular choices:

  • ‘Bishop of Llandaff’: small, scarlet, intense flowers with handsome, dark-burgundy foliage
  • ‘Miss Rose Fletcher’: an elegant, spiky, pink cactus plant with 6-inch globes of long, quilled, shell-pink petals
  • ‘Bonne Esperance’, aka ‘Good Hope’: a foot-tall dwarf that bears 1-½-inch, rosy-pink flowers all summer that are reminiscent of Victorian bedding dahlias (though it debuted in 1948)
  • ‘Kidd’s Climax’: the ultimate in irrational beauty with 10-inch “dinnerplate” flowers with hundreds of pink petals suffused with gold
  • ‘Jersey’s Beauty’: a 7-foot tall pink plant with hand-size flowers that brings great energy to the fall garden.

dahlia_full_width.jpg
Image: Kidd’s Climax. Longwood Gardens

Wit & Wisdom

  • The dahlia was named for Anders Dahl (Swedish botanist), born on March 17, 1751.
  • In the 16th century, dahlias grew wild on the hillsides in parts of Mexico. There, they were “discovered” by the Spanish, who remarked on the plant’s beauty.
  • Both dahlia flowers and tubers are edible. The tubers taste like a cross between a potato and a radish.

The Dahlia you brought to our isle
Your praises forever shall speak
‘Mid gardens as sweet as your smile
And colour as bright as your cheek.
–Lord Holland (1773–1840)

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Reader Comments

Leave a Comment

Dahlias~

Submitted by A ROCKWELL on August 23, 2021 - 10:46am

interesting Dahlias were at one time Native to Mexico; the tubers are edible; I have one dahlia in a pot;

Zone 7a Overwintering

Submitted by Karen on June 20, 2021 - 10:27pm

I'm in Maryland and I had excellent success keeping my tubers in the ground. I cut them to the ground after the hard frost, covered them with about 4 inches of pine straw, and covered that with a frost-protecting material. We had more than 2 snowfalls of 6" each. All dahlias survived and had early growth. I need to make sure I uncover them in late March, apply slug bait, and cover them with cloches until May. I had slug damage because I left the pine needles on way too long, but all the dahlias recovered from that. It was my first season growing dahlias so I was very pleased! Good luck!

Dahlia spacing

Submitted by Marcy Holland on April 5, 2021 - 8:37am

Just a comment about planting dahlias. I received multiple colors of dahlias that grew beautifully the first year. They were lifted in the fall, labeled and stored. The following year, I replanted fairly close together as the tubers were huge(think sweet potatoes!). To my surprise, every single plant bloomed RED. Evidently, the color gene in dahlias is unstable. Just a heads-up if you are tempted to plant too close together!

Will they need to be lifted out of the ground?

Submitted by Laura Smith on March 11, 2021 - 2:39pm

Hello! I live in Cincinnati, OH, I am not the best at plants I will admit - will they need to be lifted out of the ground in the region where I live to come back? I hope not, because I just planted a lot! Also, do they do okay with Lillies?

Thanks!

Wintering dahlias grown from seed

Submitted by Nicole Deibert on October 6, 2020 - 10:53am

I plant a variety of dahlia from seed (Zone 3), and the plants do grow a kind of tuber and on previous winters, I have tried to dig them up and bring them inside and I have found that they completely dry up. Could these be a variety that you can’t save the tubers? This year, I have managed to pull the blooms apart and saved seeds from them.

Will Dahlias grow under or around lilacs ?

Submitted by Trina Koch on September 7, 2020 - 8:06pm

I have several lilacs by my road, I wanted to plant dahlias around them to bloom after the lilacs. Will the dahlias grow with the lilacs? Thank you, Trina

dahlias near lilacs?

The Editors's picture

Submitted by The Editors on September 8, 2020 - 3:21pm

Ultimately, this is likely to be disappointing. Dahlias need space and lilac roots reach out about one and a half times the length of the branches—a 10-foot-wide plant can have 15-foot roots. So the dahlias would be choked out. Look around; you seldom see more than grass under lilacs, and this is why. 

Too late?

Submitted by Brooke Davidson on July 7, 2020 - 5:32pm

Is it too late to plant my dahlias? I live in zone 7b and I was just planning on planting them and not digging them up in the fall? Will they bloom?

Planting Dahlias now in Colorado

Submitted by Julie Ursetta on June 23, 2020 - 8:48pm

Can I plant the tubers now (June 23rd)? I didn't get a chance to put them in the ground earlier. Or should I wait until next year?

Dark Foliage

Submitted by Shannon on June 9, 2020 - 11:06am

I live in Zone 5b. I purchased a City Lights Golden Yellow Dahilla plant. I have it planted in a south facing garden without alot of shelter from the wind. The foliage has turned a very dark green almost black and the although it has lots of buds the flowers hardly open then just end up dying. It was doing great for the first week, then this started. Sadly the same thing happend last year. HELP!

dahlia fusarium wilt

The Editors's picture

Submitted by The Editors on June 10, 2020 - 2:34pm

Hi, Shannon. This sounds like fusarium wilt, especially since you say the same thing happened last year. Unfortunately you will need to destroy the infected plants and grow new plants in a different area.

How to grow big dalias?

Submitted by Samar Majumdar on May 30, 2020 - 10:46am

I live in Arizona, zone 9. I have problem to grow beautiful dalias. It is 110 degree F now. I planted in February, got one in each and some didn't. All are in a separate pot. Please advise.

in Arizona...

The Editors's picture

Submitted by The Editors on June 3, 2020 - 9:57am

Plants in pots tend to be hotter and dry out faster than those in ground, especially in clay pots. You’ve had some success, so you are doing some things right, but you might do better with larger pots and maybe more water (or water retaining soil). See the comments below about growing in pots, too. 

zone 8 here in texas

Submitted by Shirley l King on May 29, 2020 - 5:23pm

I have one plant blooming now and want to know if I leave it to winter in ground will it multiple like my Iris's do?

multiple dahlias?

The Editors's picture

Submitted by The Editors on June 3, 2020 - 9:53am

Your dahlia should produce tubers from the original one, but to benefit from these new ones, you need to lift (dig up) the whole cluster, then separate them. Only the tubers with “eyes” will produce flowers; the others you can discard. If your plant has never been lifted, you might want to do this now, separate any new ones, and plant those with eyes.

Dahlias

Submitted by JILL HAINES on May 25, 2020 - 5:31pm

Can Dahlias be planted in a large pot & not in a garden?

Dahlias in Containers

The Editors's picture

Submitted by The Editors on May 29, 2020 - 10:17am

Yes, dahlias can be grown in containers.  Follow the same spacing and depth requirements mentioned above. Ensure your container size–ensure it’s big enough to support the plant at maturity (generally a 12″ by 12″ container will be large enough). Cover the tuber with a few inches of soil and water it in. Be careful about watering until growth starts…but don’t let the potting media dry out. Also make sure your media is well drained so the tubers don’t rot. You’ll also need to fertilize throughout the summer.

Tubers

Submitted by Mark McFadden on May 23, 2020 - 1:20pm

If the tubers aren't planted after a season grown and dug up in the fall but not able to plant the following season and try to plant them the next season or do they get to dry and won't grow

dahlia in a pot

Submitted by Simonetta on May 20, 2020 - 3:42am

thanks for your helpful suggestions. I would like to know if I can plant them in a pot and which kind of dahlia is best to do it
thanks

Dahlias

Submitted by David Caddell on May 8, 2020 - 11:36am

Thanks for any comment. Will these flowers survive one night of below freezing temperatures?

Question re planting tubbers

Submitted by Michelle on April 19, 2020 - 3:22pm

Thanks for the helpful tips and information. I have a question, I bought Dahlia tubbers over a year ago and forgot to plant them, is it possible that they would still grow if I planted them now?

old dahlias

The Editors's picture

Submitted by The Editors on April 24, 2020 - 12:18pm

Thank YOU, Michelle! About your dahlias: We here are eternal optimists, so…Check out your tubers. If they are not dried out to a crisp, plant them, following the guidance above, and see what happens. Then consider buying more soon and plant them as “sure things.”

Novice Dahlia Grower

Submitted by Dawn on January 25, 2020 - 9:40am

I live in zone 6a. I would like to create a dense collection of dahlias to grow next to my fence - more of a bush type of look rather than individual stems. I don’t want it too short because I have some 1-11/2 foot allums along the boarder. Any suggestions?

Dahlias

The Editors's picture

Submitted by The Editors on January 27, 2020 - 3:19pm

Try planting a few different varieties with differing heights, staggering them in such a way that they still have room for themselves, but give the appearance of a dense hedge of dahlias. 

Check out Burpee’s selection of dahlias here—you can sort by height to see which would work best for you!

Dahlias

Submitted by JACKIE MARTIN on November 2, 2019 - 6:18pm

Just printed up some infor on the care of Dahlias for a neighbor of mine.

Storing Dahlias

Submitted by Patricia Haine on September 24, 2019 - 8:53am

Ive bought a dahlia in a pot. Its probably to late to plant it in the garden. So can i just leave it in the pot and store it in my none heated greenhouse over winter and plant it in the spring.

Overwintering Dahlias

The Editors's picture

Submitted by The Editors on September 24, 2019 - 3:25pm

Hi Patricia, 

If you live in USDA Zone 8 or higher, you can leave the dahlia in the pot or in the ground over the winter. In regions that experience freezing or below freezing temperatures, follow the instructions under Harvest/Storage and Taking Up the Tubers, which can be found above on this page. We hope this helps!

Save the Dahlia bulbs

Submitted by Thimy on August 25, 2019 - 2:53pm

Hi The Editors,
I live in zone 10, my Dahlias were planted in the large container. The blooming season is ending soon and I will cut the plants down to the base. Please teach me:
- Can I keep the tuber in the container until next year?
- It's very warm here, do I need to cover them with mulch?
- Can I put some small containers with planted flowers on top of the tubers? It means the tubers will be watered.
Thank you for your help.

Question about planting dates

Submitted by Laurie on July 26, 2019 - 1:04pm

I purchased some dahlia bulbs. Can I plant them in the summer or must I wait until the spring after the last frost? I’m in northern Ontario, Zone 3B, according to planthardiness website. Would putting down mulch before the winter help? Would the snow provide enough insulation? Would it be better for me to plant these bulbs in pots and take them inside during the winter? Thanks for your help.

too late to plant dahlias?

The Editors's picture

Submitted by The Editors on July 29, 2019 - 4:33pm

Dahlia bulbs are planted in the spring once risk of frost has passed. They will grow quickly and the plants will be blooming by mid to late summer.

In your region, dahlias also need to be lifted out of the ground for winter storage if you want them to bloom next year. Many gardeners treat dahlias as annuals. 

So, given where you live, you could try storing the tubers over the winter. If properly stored (usually in a vermiculite or peat moss), they should be fine. 

Pages

Growing Dahlias

Botanical Name Dahlia spp.
Plant Type Flower
Sun Exposure Full Sun
Soil Type Loamy, Sandy
Soil pH
Bloom Time Summer, Fall
Flower Color Multicolor, Orange, Pink, Purple, Red, White, Yellow
Hardiness Zones 6, 7, 8, 9, 10, 11
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