Dahlias

[FrayedEnds]

Curious if anyone on the forum grows and over-winters dahlia tubers? I had so-so luck keeping them in a bucket of sand in our garage last winter, maybe 50-60% made it. It seemed that a lot of them molded. Not sure if they rotted then molded or vice-versa, but this year I'm trying a bleach bath to possibly help. Or, they may have froze which means the mold likely had nothing to do with it. Our garage gets below freezing when we see the single digits a few times each winter.

Anyway, I dug them yesterday, about 6 days after they got a hard freeze and turned black. Rather than rinsing them with the hose this year I dipped them into a 10:1 bleach bath and brushed them off. Trimmed, divided and set out to let them harden off for about a week in our basement. I plan to wrap them lightly in grocery bags filled with peat, hoping to isolate any rot from spreading while still allowing them to breathe.

Like I said though, I don't have an ideal place to store them in the 40-50 range, so I'll put them into an old (not well insulated) cooler and fill sand around them. I'll set it up against an inside wall. I also got a cheap $10 indoor/outdoor thermometer to set the sensor in the cooler to monitor. I'm hoping this will insulate them enough that when the garage freezes they won't.

Anyone have any luck over-wintering dahlias? Tips or suggestions?

[andy10917]

I used to keep and store Dahlia tubers, but eventually the Hosta pushed them out of the beds. Here is what I remember in the way of tips:

(1) Hardening off is important.
(2) I liked to sprinkle them with Sulfur Dust, which is an antifungal. It ups the percentage that make it quite a bit.
(3) I liked a sawdust/vermiculite combo for the storage medium. Peat is good - I never liked sand.
(4) Do you have an unheated area of the basement? That's optimal. If you have to make a decision between too warm and too cold, err on the too-warm side. If it's too warm, check them in February to make sure they aren't shriveling to nothing.

[FrayedEnds]

Never thought of the sulfur dust, would it hurt to add it after I gave them the bleach bath?

I'll avoid the sand. I had hoped it would insulate from the cold better. Maybe I'll fill the cooler with peat instead.

The coldest part of the basement (walkout) is closer to 60 degrees as it has a wood stove we use during the winter.

Seems my challenge will be fighting the temperature through the winter. Time to insulate the garage.

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[andy10917]

Sulfur is still fine.

[FrayedEnds]

Thanks Andy, I appreciate the advice.

[ Post made via iPhone ]

[FrayedEnds]

We put in our order for new Dahlia bulbs and decided it would be a good time to crack open the cooler and check on the stored ones. The thermometer says they've been between 31 (eek) and 48, but so far they all look terrific and feel nice and firm. No cracks, splits, mold, rot, etc. There was a lot more condensation lining the cooler than I anticipated, but I'm not sure I want to alter what seems to be working. Anyway, thanks for the tips!

[andy10917]

Good to hear!! Now, let them sleep...

[FrayedEnds]

Just in case someone pops into this thread looking for advice, I wanted to give a quick followup.

I'm terribly disappointed with Andy's advice. I ran into a problem that I've never had until this year:
Every single bulb in storage is nice, firm and mold-free. They all have shoots and roots starting; they look terrific.

And that's the problem. Where in the hell am I going to plant them all?

[andy10917]

Cool!!! I have no solution for your new problem. You'll have to suffer terribly.