Dahlias are colorful spiky flowers which generally bloom from midsummer to first frost, when many other plants are past their best.
In the cold climates of North America, dahlias are known as tuberous-rooted tender perennials, grown from small, brown, biennial tubers planted in the spring.
Dahlias come in a rainbow of colors and even range in size, from the giant 10-inch “dinnerplate” blooms to the 2-inch lollipop-style pompons. Most varieties grow 4 to 5 feet tall.
Though not well suited to extremely hot and humid climates, such as much of Texas and Florida, dahlias brighten up any sunny garden with a growing season that’s at least 120 days long. Dahlias thrive in the cool, moist climates of the Pacific Coast, where blooms may be an inch larger and deeper.
Reader Comments
Leave a Comment
Potted Dahlias
What is the care for potted dahlias?
dahlias in pots
Growing in a pot/container is essentially the same as in the ground. Make sure that the pot is large enough to give the tubers room to spread out, and if staking/support is needed, arrange it in the pot when you plant the tuber (as if you were planting in the ground). Staking later risks injury to the tuber and potentially loss of it or the bloom.
Dahlias
I planted 6 tubers and now I have 30 plants. What do I do?
from 6 plants to 30
It’s not entirely clear: If you now have 30 plants in the ground, you can lift the tubers and divide them. This is best done in spring or fall. Use a sharp knife to cut the tubers apart. Note that only those with an eye (a dormant bud) will grow stems, so you can cut large clumps of tubers instead of discarding single ones without eyes. Let the roots dry for a day or so before storing (see above) or planting elsewhere.
confused about planting depth
Hi, I'm confused. The article says: "Plant them whole, with the growing points, or 'eyes,' facing up, about 6 to 8 inches deep. The crowns should be just above soil level."
How can they be 6-8" deep but still be at soil level??
Thanks!
confused about soil cover
Thank you for pointing out the error in the text. We have corrected it. Here’s what we learned: you want to dig a hole that’s 6 to 8 inches deep. Set the tubers into it and cover them with 2 to 3 inches of soil (some say 1 inch of soil is ok, too). As the plant grows/sprouts up, fill in with soil around it until the ground is level. BTW, if you plan to stake the dahlia, place the stake in the hole first, then the tuber and cover as described. If you wait to push a stake into the ground, you might strike and damage the tuber. Thanks again!
Dahlias
I started dahlia seeds one day and saw the seeds already laying on top of the mix already is that normal I poked the seeds back down in the mix. Thank you, Lisa.
Dahila
I put my Dahila away for the winter (MN), it is in the basement so cool and dry. I have discovered that it is growing. It is about 8-12 in in growth and very spindly. Is there anything I can do stop the growth? Can / should I cut it back ?
Thanks for any help. ( I'm a first time owner)
dahlias that sprout in storage
The general consensus is not to break off the shoots and plant the dahlia tuber as you would normally. If there is any rot, cut it off, and be aware that if the tubers are dried out, they may not thrive or grow. A reader wrote in to endorse the idea of leaving the tubers as is: “I never break them off [when] they grow new shoots, [and] never have a problem with them growing.”
2 Dahlia plants, 1 flowering, the other not
Hi, I have 2 pots of Dahlia, one is flowering nice but the other is just growing bushy with tiny buds which do not open. How do I treat it?
Thank you from Ghana.
Dahlias
What if some tubers fall off when pulling out? Are they still good?
Rotten Tubers
If your dahlia tubers fall apart when being lifted out of the ground, then they are rotten and should be disposed of. If it’s just the foliage that detaches from the tubers, the tubers themselves are probably just fine; you’ll have to dig them up and have a closer look. If they are squishy and fall apart easily, then they are no good. In the fall, especially after a frost, the foliage dies off naturally, which is when it easily detaches from the tuber.
dahlia
I live in the Seattle area, did not replant my very dark purple dahlia for 5 yrs, this year the plant bloom in a yellow and orange color, WHY?
Thank you, Renee
Color-Changing Dahlia
Some cultivars of dahlias (and other common-grown flowers) are not genetically “stable,” meaning the flowers they send up may not always be the same color or shape. Your original purple dahlia was likely a hybrid of several other dahlias, and it just so happens that another color showed up this time.
Colour changing Dahlias
I live in England and have experienced this with blue hydrangeas that turned pink. I researched and learnt that at transplanting, the acidity of the soil has a bearing on the flower colour. Solution is to buy erocutious compost. I use this for camelias as well
dahlia
For the last two years I have grown the most abundant and beautiful dahlia. They had very large blooms. However after I dug them up in the fall and stored them over winter they did not grow. This year I bought new tubers and they grew tall but the flowers did not fully bloom they were undeveloped and looked sick. It was very dry here so I watered them but they were slow to come up and the blooms would not develop
Weak Dahlias
There are a couple things that could have resulted in weak dahlias:
1. The tubers themselves could have come from a bad or diseased source.
2. There aren’t enough nutrients in the soil. Did you add any fertilizer to the soil before planting? Dahlias are heavy feeders, so having two seasons of dahlias grow in the same spot without any extra fertilizer could have simply depleted the soil’s resources. See our advice, above, about fertilizing dahlias.
dahlias falling over
my dahlias did spectacularly well in a large pot from late spring until mid august, I did not stake them. now they have fallen over. how far back can I prune them. also the tuber is about half above ground. should I bury it?
more on my dahlias falling over
I live in so ind zone 6. first frost may be as late as thanksgiving! or early as mid october. also. I watered my plant heavily the nite before it fell over
Foliage should be cut back to
Foliage should be cut back to 2 to 4 inches above ground and lifting and separating should be completed in early fall. Don’t bury it if you are going to lift to overwinter it later in season.
Dahlias
I have replanted my tubers each year and all the plants that have bloomed are yellow blossoms even though many were of a different color...why have they all turned to a yellow blossom??
Dahlias
I have had my Dahlias in the ground for some time in Zone 6. All of the leaves have been deep green until this week. A few of the plants have begun to have very light green almost yellow on some of the leaves. What should I do, Fertilize again ??What with? an you help me.
??
dahlias
could someone please help me !!! i planted my tubers under the understanding they were dwarf type not only have the plants overtaken the space that i allocated but also swarming with blue fly cant go near them for flies!!! help :-(
Rotting blooms
Before my dahlia blooms actually open, they turn brown and rot. Any suggestions? Thanks!
dahlia rot
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.
How long do blooms last?
I have a small dahlia plant in a big planter on my back deck. The plant seems to be doing well, and has many buds. I'm wondering how long an individual dahlia bloom is supposed to last? It seems that my blooms only last a maximum of 3-4 days before they turn brown and wilt away. Are they not getting enough sun?
Dog in Dalias
My dog just broke the new plant down to the tubers, it was partly my fault too. What should I do? Dig the tubers up and try putting them in the fridge, or will it resprout in the pot I have it in? I'm so sad.
Dog in Dahlias
Oh, those doggies! It depends. If the dahlia broke off at the base of the plant, it’s fine for next year. But if the tubers are pulled off or if they break off, the buds are almost always lost and the tubers are worthless.
Moving newly sprouted tubers
Hi there,
I planted some tubers thinking I had lost my last years tubers due to a cold and wet winter. Now the old plants are growing as well as the new and they are crowed. The plants are about 6 inches tall and full is it safe to move them?
Moving the flowers...
I seriously have the same question. I bought some of the dinner plate dahlias and underestimated how big they'd get and now I seriously need to move them. Is it safe to do so?
Pages