Are my dahlias dead?

alexemmersonuk

Hi all - 
If you are in the East of the UK, you know it's been frosty for a few nights now. 

Back in June, I bought some LOVELY dahlias and I was told they are perennial and they would come back every year. I have a feeling I should have moved them indoors or covered them with garden fleece, but I haven't (I know I should have, but it's been a tough few weeks).

I guess my question is are they definitely dead now? Or should I cover them now and hope for the best? 

A 

Paul B3

One of my customers in Lincolnshire leaves her Dahlias outside all Winter every year ; with due reliability they always return in late Spring . Drainage and soil composition are vitally important here ; an open and friable medium is obviously advantageous over a sticky clay .

If you've already cut them down , then by all means cover them . Lifting them from wet ground now may do more harm than good . Good luck !

P.

thevictorian

I live in norwich as well and lifted most of mine before the cold hit but I did leave some in the ground. I cover them heavily with a layer of bark and then bracken, which keeps the winter wet off them as well. If your soil is like ours, then it is sandy and we'll drained, so cold is what i'd worry about. If they were planted shallow then you might not have much luck but our neighbours are planted so you can sometimes see the tubers sticking out and they leave them in the ground every year with no mulch and no problems.

I would cover them up now as well rather than try to dig them up. 

alexemmersonuk

Thank you - to be clear, I am a bit of a beginner and may be doing something wrong here, but mine are in pots.... Is that a bad idea??? Also, they're not flowering at the moment obviously, so how can I tell if they are still alive? 

Pete.8

I grow them in the garden and also have 2 Arabian Night in very big pots which they've been in for many years. They been through the Beast From the East etc over the years and they pop up each year.
I often lose 2 or 3 out of about 20 in the garden, but I sow a few seeds in early Spring to replace any I loose. I grow Bishops Children in the garden.

You can lift and store them somewhere frost free if you want.
But tbh I'd move them somewhere sheltered or frost-free if poss and see what comes up in late Spring - I don't see mine until about late May
Under the soil the stem main stems connect to a load of tubers.
If the tubers are still hard then they're OK - if they're mushy, they're finished and best removed o they don't damage others.
They look like this-

Loxley

You will know next spring, no way of telling right now! If they are in pots bring them right up against a house wall for protection, although it's a bit late now. The fact they're in pots counts against them because the roots will get colder in a pot than in the ground - the pot will freeze all the way through whereas the ground will only freeze for a few inches down.

That said I have (accidentally) left tubers on the surface of the soil over winter before and they somehow survived. That may have been a mild winter though.

alexemmersonuk

Thank you so much! 

Pete.8

PS - make sure the pots are raised off the ground a bit so the pots can drain easily.
I use 3 or 4 little bits of wood or bits or polystyrene packing.
Aside from frost, the worst enemy is wet, which will rot the tubers - and we get a lot of wet over winter

Paul B3

As your Dahlias are in pots , simply lift them to a frost-free and sheltered place and keep bone-dry until the Spring . Mine are in pots also and spend every Winter in an unheated greenhouse . I only grow the reddish foliaged Bishop series (single flowers for the bees);they stay in the same compost for around three-years which is replenished by slow-release granular feed every Spring . Have been looking good for many years now .

Fairygirl

It's wet cold that's the problem for them. As they're potted, just lift them to a frost free place as said. If you've only had a few frosty nights, and only a few degrees below zero or similar, they're probably fine. 
I lifted mine ages ages ago [in pots] because they were very wet. Now in boxes in the shed with some paper cardboard etc to keep them frost free. Mine are always potted as I certainly couldn't leave them in the ground, and they wouldn't have survived our recent weather here, but in drier, milder areas, especially if you have lighter, freer draining soil, you can cut them back and mulch. Many people find that works 

As @Loxley says - you really won't know until spring though. 

Athelas

alexemmersonuk said:

Thank you - to be clear, I am a bit of a beginner and may be doing something wrong here, but mine are in pots.... Is that a bad idea??? Also, they're not flowering at the moment obviously, so how can I tell if they are still alive? 

It’s fine to grow dahlias in pots — many on here do — especially if your soil is heavy clay or otherwise not suited for dahlias, or there’s limited space in the ground.

Your dahlias won’t necessarily be dead (unless the tubers are mushy, as @Pete.8 mentioned). The first frost will have blackened the foliage and induced a state of dormancy, which is actually what is needed before lifting the tubers.

Here’s a link with detailed information on how to lift the tubers: https://diygardening.co.uk/our-plants/dahlias/lift-store-dahlias/

In March or April, you can pot the tubers up (after inspecting for mushy/rotten parts — squeeze each part of the tuber and cut off anything that feels soft and squishy, making sure to preserve the central stem… the tubers should feel firm like a potato), and then wait to see if shoots will grow. I like Sarah Raven’s very simple video here on how to pot up tubers: https://youtu.be/fHpiPzia6Dw?list=TLGGVcT-9vfD5kExNjEyMjAyMg.