How long of a dormant period do dahlias actually require?

7 years ago

Im wondering how long after cutting dahlias back do they have to be stored for. Can I restart them after only a couple of months of dormancy?

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cicivacation

7 years ago

last modified: 7 years ago

My understanding is that they don't need any dormancy time... What they need is hot days (75-85 ideal) with cool nights to really thrive. As every place on this earth that I know of has variations of temp and rainfall, dahlias have an illusion of needing dormancy, but I don't believe that is truly the case.

Here in North East USA, the plants fail after a hard frost reduces the stalks to mush. After the plant is cut/frosted, the tuber will put up new sprouts, and a new plant can thrive until the next frost.

In Florida, the dahlias do best in cooler times, but rot out quickly in winter rains. Growers I've talked to there actually get blooms in the early spring and late fall on two sets of plants, as the summer heat and winter rains kill off the plants and new ones sprout.

A grower I know smuggled dahlia tubers from Australia, which has its seasons reversed from North America. He started them up right away for our spring season with only a month of dormancy, with no problems.

I've been gifted tubers from Florida that had just been dug prior to their winter rains, with sprouts still on them, and I had them growing under lights just fine. (Of course, keeping them under lights for five months really was not fun, so I haven't repeated that trial. Lol)

One thing I keep on hearing from growers is the 'east coast vs west coast disconnect' theory, which is that if you plant a tuber from the opposite coast, it takes a couple season for the tuber to 'get used to' the new growing region. I think that is absolutely ridiculous, as the tubers are simply bags of starch with the special meristem tissue (eyes) on the heads of the tubers that create the plant material. Cut a sprout, root it, and it grows new tubers. The relocated tuber can contain too much nitrogen, or residual fungal spores that might cause rotting, but a sprout is a sprout is a sprout. Plant it in the right conditions, and it will grow. However, there are growers that will swear up and down that opposite coast dahlia tubers need time to 'settle.'

Probably too much information for a simple question, but it is a great query that requires knowledge of what a dahlia tuber is, and how it grows. Hope this helps.

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Comments (8)

Florida_Joe's_Z10a
Original Author
7 years ago
No, not too much information at all. In fact just perfect. I'm moving to Florida this winter and want to take my tubers so fantastic news! I hear the drier sunnier, cooler night season in southern Florida is winter and the hot, wet, cloudier, season is summer. So i wanted to try to regrow the tubers for the winter months and lift them for the wettest summer months
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I found it interesting that you had assumed dahlias needed to keep their dead stalks like spring bulbs... Never occurred to me, but in a more temperate region that has a slow die-off of the plants (instead of a sudden 'BAM' frost of death that my dahlias experience), that assumption makes more sense. I strongly doubt the tubers are continuing to store energy or keep growing as the foliage fades, as that is a sign of impending dormancy. And as you have multiple years of tubers in each clump, the maturity of the tubers doesn't matter as much, either. I have been taught that cuttings started in spring need three months to develop well-matured tubers that will store out of the soil... They actually can start developing tubers within a month, and be stored as a dormant pot root in their soil for the best shot at overwintering a valuable variety. I've heard of several old timers (all long-passed now, grandparents to my contemporaries) who successfully layered tubers in sand within lined apple crates and coal buckets here in the East. I bet vermiculite wasn't as readily available then. ;-) Nowadays, folks I have talked to report a lower success rate when testing sand against others as a storage medium, but that is after severing the feeder roots when dividing. Sounds like your undisturbed clumps do just fine.
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eczekalski
7 years ago
Cici, then I wonder what those tubers from Holland need? <smile> Friend has ordered a few times from what she thought was a local, Midwest source. When she had a problem, it was blamed on his supplier in Holland. Sigh...
cicivacation
7 years ago
last modified: 7 years ago
Most of the 'big box stores' (like home depot, lowes, walmart) offer
cheap Holland pot roots, with the varietal name, form and size often being
incorrect.

Holland vendors tend to not care about names, so lots of NOID (no identification) plants result from such purchases. Those varieties are produced from massive amounts of cuttings, grown very close together to create small pot roots that are cheap to ship. Often, multiple tuber necks are broken on each clump, but if planted intact, the clumps will have several sprouts despite the nasty look of the clump.

Occasionally, serious growers purchase them to obtain a variety that is rare in the US, and are sometimes gratified when it blooms true. Often, the gamble is futile, but for a couple of bucks, it is worth it for the rare ones.
cicivacation
7 years ago
Jostus, I know a grower in Gainsville, FL that uses 5 gallon mesh pots to grow ON TOP OF landscape cloth. Last year, he tried directly in the ground and lost most of his stock. He went back to the mesh pots, and they are flourishing again.

Perhaps raised beds would do the same thing for you, to help wick away the excess moisture from the ground.
Florida_Joe's_Z10a thanked cicivacation
Jayne Froney
3 years ago
I have question regarding Dahlia's in Florida... do you need to cut them back in the winter or just leave in the ground... do they stop blooming at some point?
cicivacation
3 years ago
Hmmm... its been a while since I've talked to the FL grower.... if I remember right, he said that the dahlias naturally die back twice each year, in the heat of June/July and rainy season of Nov/Dec with blooms really early spring and late fall. Its not that dahlia tubers NEED to go dormant, its that there really isn't any climate that is evenly temperate for them to thrive in year-round. Too much heat or cold, OR too much/little water will trigger dormancy.

I seem to remember sending tubers to the FL Grower in January so he could plant out February. The images of his first blooms in April always stirred the green-eyed giant in me, and he was likewise jealous of our riot of color in the northern states in August/Sept. I miss a friend in New Zealand who always shared her summer images in OUR winter in the US... always a delight to see picts on the opposite season to us.
PRO
Blue Pool Gardens
2 years ago
GREAT info! Thanks all!!!!!

How long of a dormant period do dahlias actually require?

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Comments (8)

Florida_Joe's_Z10a
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How long of a dormant period do dahlias actually require?

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Comments (8)

Florida_Joe's_Z10aOriginal Author

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Florida_Joe's_Z10a
Original Author