No Tubers What Happened?

This is my third year growing bedding Dahlias (have had good success!), but only my second year
growing "regular" Dahlias. Bought the tubers in a package at WalMart, package was labeled "BiColor Duet". Planted after all danger of frost, took forever to sprout. Beautiful flowers, but all
the plants quit flowering around the end of August, although foliage was still lush & green. Decided
to dig the tubers up yesterday for winter storage, and while there were some "roots" underground
where the tubers should be, there were NO tubers at all. Same thing happened last year, but I figured
I'd done something wrong due to inexperience growing Dahlias. What could have caused this? We've had much higher-than-average rainfall over the summer (record breaking some weeks), could
the excessive rain have caused the tubers to rot & disappear?? I did not fertilize the Dahlias, and
they (BiColor Duet) had no problems with pests, so no chemicals applied. Just quit flowering early
and now no tubers left to store.

That's a real mystery, Jolie B. I've had years when the plant bloomed and looked like a normal, healthy dahlia blooming however it was going to bloom, but come digging time, there was only the mother tuber and a few feeder roots: no new tubers had formed whatsoever. I've also had the mother tubers rotted 95% away but, thankfully, new roots/tubers formed enough to grow the plant to maturity.

I can only offer a guess that your heavy rains did rot the original tuber/s, washed away nutrients needed to promote additional bloom and tuber formation leaving you at this unfortunate juncture. What did the roots look like when you dug them up? Something had to support that plant's healthy green foliage growth regardless of the lack of flowers. If there's any kind of root mass whatsoever it might be worth trying to save, but if they're stringy or thin I wouldn't bother. Just replace Duet next year and hope for less rain.

I have liked Osmocote veggie fertilizer or other sustained-action fertilizers to last throughout the growing season. Other growers add manure or a dose of fertilizer no later than early August to sustain plants in the final weeks before die off and to bolster bloom and tuber formation.

Wish I could offer a sure explanation, but I can't. There's always a mystery or a miracle with dahlias every year. Never fails. Don't give up: there's about 50,000 more varieties to try out there!

I had this happen to several of mine this year. About 5-6 of my earliest planted tubers had no tuber left, but, just as Pooch says, had a decent root system that had supported the plant. I, too, had super duper rains that rotted them. The first time or two this happened, I thought I had lost my mind-"What no tuber? Not even rotted remains of one?"
Then, I started sifting verrrryyyy carefully through the dirt, where I knew it should be. I would find a lot of tuber skins (like tater skins, but not nearly as tasty) but no actual tuber. Like yours, the roots sustained the plant, but I had stopped getting any blooms after their first bursts and the rains.

In Murphy's Law-like fashion, they were all the varieties I had really hoped to propagate and share with my dahlia buddy's here-G. Hoek, M. Duross, E. Huston.
Sigh...Oh well, lesson learned-there's always next year, right? Good luck-don't get discouraged!

Carrie

This is very interesting. I had the same situation with a few of the ones I was really hoping would produce fat, healthy tubers. Most were fine, though. We had a lot of rain earlier in the summer and it was cooler than normal but we sure had gorgeous blooms! I'll go with Pooch's "mystery or miracle" approach. All gardening is truly full of mysteries and miracles!

I had a small unknown dahlia growing in a pot this past summer. It grew out bloomed, then died, then put up new shoots later in summer,too late to bloom. I was removing tubers to clean and dry yesterday, I pulled on plant and was shocked to pull out a root 6 inches long and straight. No tubers just long root, that had broke off something in bottom of pot. Mysteries and Miracles Indeed.
taj

Annie - would a one inch (or more) layer of gravel beneath the tubers (as they're planted) help with the drainage for dahlias in the event we get another frightful year of rain in 2010?

Thank you all so much for your replies. I feel much better, realizing this can be something that just happens sometimes and not something I caused! Poochella, two of the three plants had barely any roots at all (guess just enough to keep the plants alive and green); the third plant did have a bunch of roots, but they were thin & stringy & didn't look "right",
so I threw them out. Didn't occur to me I could try replanting the roots, but will keep that in mind for next year.

Will definitely fertilize next year, to replace nutrients washed away by the rain (something else that did not occur to me).

I absolutely love dahlias! My only problem is very limited (tiny!) garden space that gets sun,
and wanting one of every single dahlia variety I see! Already looking forward to buying new tubers and trying again next year.

You might want to try potting up some of them.

Can the dahlias that get really tall be potted successfully, or is it best to stick with smaller
(shorter) varieties?

I'd say 3' and under would be your best bets.

Thanks, pirl!

Pirl re the gravel: I think if you put it right under the tuber at planting the new little roots won't have a very happy or nourishing environment, though they would have good drainage. Maybe placing it below a few inches would help, but the roots will also get entwined in that gravel as they grow through the season. Raising beds would be an option, and amending the soil over time to keep it well-draining is always a good idea. I think people add sand too but that would be labor intensive in a large area.

Hope mine is well-drained: we're on our 7th inch of rain in about 10 days. Pretty silly to think that I was wondering if the soil was too dry earlier this month. Looks like it will be another typical soggy digging adventure this year.

JolieB, I've seen those plants that have just one weird 'tap' sort of root and thin roots. Really surprising to find so little under a robust plant. I doubt they would store well, so tossing them was probably a good idea. Here's the best article I've found on growing in pots and it works well even for 4 footers. You do need to have the taller ones staked or up against a railing where they can be supported. It's easy to get the tubers out too, or just let them dry out and store in the pot in an area where they won't freeze. (I haven't done that, but Daisyruffles has succeeded with that.)

http://www.dahlia.org/index.php?page=growing-dahlias-in-pots

Hi JolieB ^_^ Ditto on the rot theory under your growing conditions this year and also ditto on the mystery of why sometimes a plant is just not tuberlifik. I have noted though that those with root competition with nearby shrubby things are often tuber challenged.

Wow-nice link Pooch. That's the most detailed I've seen on container growing. Thank you.


Carrie

Hi all I am back. From the start of the thread I note the dahlia was bought from a big box vendor. These folks buy from huge Dutch growers who get their product from planted cuttings. If there is no leaf node with the cutting there will be no tubers at the end of the season. I don't think it was too much rain. This does not happen with all pot tubers from the Netherlands but will happen at times.

Steve

Jolie, I grew all my dahlias in pots this year. That included a variety called Bill Williams that was 6' tall. No problems until the end of the year (October) when the wind blew the plant, but not the pot, over. Plentiful flowers, large tuber clumps from them. It had a 12" nursery pot for a home. Bill Williams was my best dahlia in terms of vigor, flowering and size. I bought it from Walmart.

Regarding gravel in the soil, you would be well advised to look at the stickies in the Container Gardening forum started by tapla. There's a lot of good information there.

Regarding tuber production, I have recently read that dahlias will not develop tubers when the number of daylight hours is 14 or greater. The interesting thing about the discussion was that the intensity of light required to suppress tuber production was low. I could see that some circumstances such as floodlights used for night display, street or outdoor lights of sufficient intensity, etc, could theoretically suppress tuber production. By any chance were your plants in a place where they get a lot of nighttime artificial light?

Krowten-what substrate/potting material did you use for your dahlias? I tried this and lost all of mine to rot. Mostly due to rains, and lack of cover during the rainy season. But, also, the potting mixture I used held too much moisture for them. Just curious to know if it was close to what was written about in Pooch's link. Thanks in advance,

Carrie

Carrie, I just used stuff from my compost bin. Keep in mind that my compost bin contains a lot of soil from old pots - I always dump old potting soil there when I re-pot or up-pot my plants. Having said that, there is a strong component of pine bark, porous and non-porous silica, some perlite, some vermiculite as well at trimmings. I'm sorry I can't give you a better answer, but I'm one of those guys that looks at the soil when I am potting and says "whmmm, needs some ...." and makes the adjustment on the spot. Pine bark is the most significant component. In Florida, I would think you would have access to lots of sand. My guess (and it is a guess) is that dahlias would react well to a fast draining mix such as discussed in the container gardening forum stickies.

Alson, not knowing any better, I planted my starter tubers only and inch or two deep. Most of the tubers had come from jamlover who had coated them with sulfur as well.

How strange and interesting! I had a few border Dahlias in mixed containers that I was surprised to find had developed small clumps of tubers, and the tubers are very thin. They don't look like there could be much stored carbohydrates in there. I thought since they were in potting soil they'd produce larger tubers, but I did have several other plants in the containers with them. Sounds like root competition could have been the issue.

I'm curious if Dahlias tuber production has something to do with soil temp, kinda like sweet potatoes. I've had ornamental sweet potatoes in the ground that produced no tubers, and others in pots that produced huge tubers. I assumed it had something to do with containers providing a warmer root zone. Although that wouldn't make much sense with Dahlias (that grow so well in the Northwest), especially in the South.

gemini, I grew the same varieties in pots and in ground last year and found the tuber production was approximately the same on those varieties. The pots were big 14" shrub pots, black plastic so got plenty of heat. It's confounding to try to find a pattern with dahlias treated pretty much the same way through the season.

The other day I dug 2 of the same variety grown less than 2' apart. One clump had over 10 tubers and the other had about 2 usable ones and very few others. Varies from year to year on plants too, though some are just magnificent year after year.

Are Ornamental Sweet Potatoes the ones grown for the vine?

And it happened again to one of my beloved old cultivars "Contessa." Dug up the plant which did great all season: mother tuber and absolutely nothing else but feeder roots. Nothing even remotely close to a thin extra tuber had formed. So now on to the begging to whomever I might have sent Contessa over the years to send her back! Lenjo? Anyone else?

Krowten, no, my dahlias got absolutely no nighttime artificial light at all.