Dahlia tubers

[roitelet]

I have tried to overwinter dahlia tubers lots of times but they always rot. Last year I didn't lift them and because of the very mild winter they survived and have been magnificent. I would like to save them for next year so how should I go about it.

Thanks

[WendyC]

I do lift mine and leave them to dry out for a couple of weeks. As you have found out being too wet is more of a problem. I have seen advice to store them upside down for a while to allow the hollow stems to dry out. I then put them in a mushroom box with barely damp old compost and they sit on the potting bench all winter. Trouble is we don't know what sort of winter we are going to have. You could hedge your bets for another mild winter and give them a mulch and hope for the best. Or lift them and hope they don't rot off. Keeping them pretty dry does help, also checking them over from time to time so you can limit the spread of any rots.

[Martin H]

I sympathise. I lose some whether I lift and store them or just leave them in the ground. But if they are rotting it's because you haven't dried them out properly.
You need to get as much soil off as you can, then stand them upside down to drain in the shed for a week or two.

When they are bone dry you can pack them away somewhere frost free until the spring.

It's kind of like what Monty Don was doing to his banana in Gardeners World yesterday.

[Guest]

I don't store mine I leave them in the ground but I am not precious about them. To cover any loses of any I particularly like I take root and stem cuttings. Then for everything else I keep seed and have pot luck surprise dahlias the following year.

[roitelet]

Thanks folks, I will try again and be more vigilant, might even bring them indoors to be sure they escape any frost. It has been known to drop as low as -20 C here, last year was an exception.

[starloc]

I am leaving mine in the ground, it can drop very very low here, but the ground is sandy so waterlogging is not a problem, if they die they die....neighbours say thy will be ok

Most times its only about -5C to 5C at night in the winter much warmer during the day in the sun , we are in a very good place between mountains, but a few days here and there its -15C down to the lowest I have had of -35C a couple of years ago but it was only for a few hours, next day was 18C

I will pile a great heap of sticks and straw over them if it looks like the cold is hanging round too long

If you are diging them up and storing them dry, dust them with sulphur to prevent mould

[Scarlet]

I do a bit of both. Often I think one or two have died but on closer inspection in Spring I find that the new shoots have been nibbled off by the dreaded slugs. It's worth doing the rounds at night or sprinkling sand on the spot where the plants are expected to come up...or use slug pellets.

[Martin H]

Yes, if left outside you need to be really vigilant in spring. Slugs and snails come from miles around to feast on the new shoots.

[Kristen]

I lift mine because if I leave them in the ground they start much later in the year, and thus later to start flowering too.

[Zelenina]

The first time I looked at this house, thinking of buying it, the owners said there was no light in the cellar, so I poked my camera down and took a few random flash photos. When I looked at the pics later I saw a huge tangled mass of alien white growths

They turned out to be dahlia tubers that had been down there for a whole year. Their shoots were trying to reach a small chink of light coming from outside. The old woman who lived here must've dug them up in the autumn, and then she died in January so they didn't get replanted.

They seemed determined to live, so I brought them up into the light, and trimmed back the long white shoots, and they started making some new green leaves. And most of them grew and flowered after I replanted them.

Then last winter was so mild that I didn't bother digging them up again, and only one plant regrew in the spring. They were all the same variety, so I guess it was no great loss. But I'll be digging it up soon and putting it back down below.

[Kristen]

Then last winter was so mild that I didn't bother digging them up again, and only one plant regrew in the spring.

I think it is much more the wet, rather than cold (provided not too severe) that is the issue. Really wet Autumn here last year (and this ...) and clay makes for wet soil in winter. On free draining soil I would expect a much better chance of a good survival rate in all but the coldest winters.

[Zelenina]

Yes it may have been the wet, although my soil is free draining. Or maybe they were just weakened by their year in the cellar.

[bramble]

Mine have been in the ground for about ten years now and I just leave them to it. So far so good.