Question
Hi
I live in Vancouver, BC, Canada and I am wondering how I should winterize my Dahlia.  I should also mention that my Dahlia is planted in a container.  We don't always get a good frost and sometimes the frost doesn't come until quite late in the year.  Can I leave my Dahlia in its container?  How do I go about pruning it?  do I prune it or just leave it be?  This is my first winter with the Dahlia.  Can you tell?

Julie

Answer
Hi Julie,
Thanx for your question.  Dahlias are hardy in USDA Zones 7-11.  I live in a cooler zone and I let the first frost kill back my dahlia.  I cut off the dead growth and then lift the tuber to store in a cool, dry, dark basement (cellar) for the winter.  Because you are in Zone 8a, your soil will not freeze over and this is what causes death to a dahlia tuber.  You can lift the tuber if you prefer, dust it with anti-fungal horticultural powder and store it in a dark, cool, dry place where it will remain dormant or you can leave it in the pot and when spring comes it will come back up.  Cannas will overwinter this way too.  If you do lift the tuber, you can plant it in your pot after the last frost and it will come back.  While the dahlia is growing I wouldn't prune it.  If you are growing dinner plate dahlias or looking for show quality blossoms, start pinching off side blossoms and allow the main blossom to grow.  You will get a bigger, much more impressive blossom this way.  I hope this helps.
Tom