North Shore Gardening Life

Days Until First Frost

Should I Bother With Dahlias?

Question from Lucy Grey:

Should I bother with dahlias?  People tell me they’re too much work.

Answer by Elizabeth:  Yes, they are a lot of work, but they are so beautiful!  

This one pictured below is an example that I grew from seed.  The parent was the hybrid Dahlia “Bishop of Llandaff” (pictured in thumbnail). It didn’t come true because it’s from a hybrid, but what a stunner I think it looks lovely combined with the green and white leaves of a milk thistle (Silybum marianum).  

But – the problem is, they won’t survive the winter.  Not in our zone 5 climate. They are hardy in zones 8-10, which is way warmer that we ever can be.  The tubers will die of the cold. 

If you want to keep them to plant next year, the strategy is to watch for when the leaves have just been bitten by frost, cut them down leaving a stalk or stalks of about 4″, and then leave them in the ground for about a week or two.

After that, dig them up, let them dry and then store them buried in wood shavings, vermiculite, dry potting compost or something like that in big paper bags or cardboard boxes.  

In spite of what many say, I find that you don’t need to bother cleaning off the dirt.  Just make sure that they are absolutely dry before storing them in a cool, airy, dark, frost-free place.

I sprinkle them with cinnamon which is supposed to help keep mold at bay.

The best temperature to store them at is 4-10 degrees, and humidity should be about 75-80%.  Too much variation in these will cause tubers to start rotting, drying out or sprouting prematurely.  In fact it’s always a good idea to check occasionally for any of this and make the appropriate adjustments in temperature or humidity, and get rid of any rotting bits. 

If you don’t want to go to all this bother, or if you don’t have an appropriate place to store them, you can treat them as annuals and discard the tubers whenever you do your clean-up.

Another option at the end of the season is to give the tubers to friends who LOVE dahlias.  They will be delighted, I’m sure.

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