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  • Jane Westoby

When to plant Dahlias out

Bright Coloured Dahlias

I'm literally having heart palpitations right now seeing some Dahlias being planted out, why so soon? why is everyone in such a rush? In many cases to plant Dahlias out earlier does not mean earlier blooms.

Dahlias are short day plants, so they will be at the peak around autumn equinox here in the UK. This is when night and day are equal lengths, like in Mexico where they originate from. They love the heat but do not need more than 12 hours of sunlight per day.

In terms of planting out they don't like to be either too wet or too cold and they need to be protected from frost as this will kill the tubers. So its best to wait until after your last frost date. Here were I live in Hampshire this is around the end of April.

I say this, however, as long at the tubers are buried sufficiently they will be protected from a light frost so make sure you don't leave them poking out of the soil just incase. If you do get a frost the leaves will blacken but they will soon re sprout of the tuners are adequately protected.

Planting Dahlias

Dig a hole big enough to fit the tuber in without any forcing, cover with soil, water in and add a layer of mulch or compost to around the top. This extra layer of compost will act as an extra layer of thermal insulation, keep weeds down and moisture in. I would also recommend pre sprouting Dahlias in pots so that you are planting out something which can withstand pests. Stems around 10cm tall should be adequately large enough.

Dahlia Wizard of Oz

The other thing which Dahlias don't like is too much water. If your ground is poorly drained, maybe you have clay soil, or at risk of flooding then its wise to take some steps to protect your Dahlias otherwise the tubers will rot. You can use a trench method or use raised beds to raise the tuners up above the waterline.

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