Kitchen Garden Forum

Just a quick question!

I knew we had a frost coming & thought about cutting down the dahlias on Sunday but then thought if the foliage isn't there the frost would be more liable to go down the wee bit of stem left so didn't. Would this be the case and also do the actual tubers need the frost?

I believe the idea is the tubers must be kept frost free, the tops are sacrificial,my Dahlias are in the greenhouse and have been for a couple of weeks in their pots. I just wrap them in fleece and leave them in the soil.

I have been less cautious: ours were well frosted last week so I cut them down completely, then dug a big hole and put the tubers into it, covered by the excavated soil - a sort of clamp, I suppose. If the winter is not too hard, they should survive, if they are killed, it's not the end of the world .......

I brought mine in last week after the first frost. I keep them in a deep tray of dry compost in a frost free place. They have survived outside on the odd occasion I've left them in the garden but have been severely set back by slugs eating the new shoots in spring. So if I want to keep them I bring them in. It's also very easy to take cuttings if you detach a few of the new shoots and pot them up before planting them out again after the frosts next year.

I leave mine until the frost has well killed the tops, they were hanging on as we had only had ground frosts until -0.5°C last night so that might be it. I cut them down then dig them up and knock off most of the soil and dry them upside down on the greenhouse staging (early frosts don't usually get into the insulated greenhouse) to let the moisture drain out of the stems. I store them in bread trays in the integral garage that is frost free. They can get a bit dry, they would be better in dry compost as PP does, but they do shoot OK when I pot them up. I grow entirely from cuttings and if they still have plenty of shoots I usually give the tubers away when I have enough plants.

I don’t have a lot of them but leave mine in the ground after the tops have been cut down and cover the stumps with a generous mound of co post. So far they’ve survived. I had one exceptionally large plant this year and wonder if the timbers can actually be sliced in two or does this make them vulnerable to infection and rotting? Perhaps I’m off just leaving that one alone rather than tempting fate!

Dear Primrose,
dividing tubers is relatively easy but they MUST have a piece of the stem base on each division as this is where the new shoots sprout from. It is a good idea to do this in the spring when the growth starts. Dig them up then and divide them; leave in a dry spot to allow any cuts to heal and then re-plant. However if the tuber has been in the ground for several years then it may have divided itself and all you have to do is tease the pieces apart and replant there and then.
This tip also applies to herbaceous paeonies.
Regards Sally Wright.

Thanks Sally. I have one particularly nice one so will try it in the spring. Right now it's(hopefully) safely tucked up under a mound of earth for winter.

I just dig around the biggish ones & take individual tubers. I don't cut them in half, don't have to as when you dig they have loads of tubers with stems & roots.

If you have plenty of tubers you can cook them. I grated some and made some very tasty rosti with them.

Hi PP! I had to look twice when this popped up again. At the weekend some of the bigger ones were showing a few shoots so they seemed to have survived. I will split them again this year as they had a mass of tubers when I had a poke around. I planted loads of the easier to reach tubers from them in the garden at home but no sign of them popping up yet.

I knew they were edible but can you use all types of tubers or just specific varieties? What do they taste of?

You can use any but they say some taste nicer than others. I just use whichever has the biggest tubers so there are plenty left to grow and haven't noticed much difference in taste. It says they get sweeter with storage. They do contain inulin like Jerusalem artichokes so may cause gas.

Have a look at James Wong's blog, he is very enthusiastic about them and includes a recipe for dahlia and red onion rosti.

Cheers PP! I like Jerusalem artichokes & have the remedy for the side effects for those. (Asafoetida - Indian spice with a mild onion flavour). I will give them a go when I have to sort them this year & check his blog.

Hello,
I knew they had to be edible by the way the rabbits dig down to get to the tubers I leave in the ground over the winter!!
However they usually survive the attack enough to grow on and put some shoots up.
Hilary