New to growing dahlias? Wondering when those beautiful tubers need to be unearthed and prepped for winter storage? In Terrace, BC, Canada we start chopping down our dahlias in the first week of October – the season of long shadows and lower temps.
Its mid-September when frost can visit anytime to bring an abrupt end to fresh blooms and bouquets. Usually we don’t see frost until mid-October… sometimes earlier and sometimes later. We like to get the dahlias cut down before the frost comes. Why? Because after a frost, the leaves and stems blacken and start decomposing, becoming slimy and slippery. The job is miles easier before this happens!
We don’t wait for frost to start chopping – its just a general guideline of when you can start lifting tubers. Generally, if your dahlias have been growing for 4 months (~120 days) they’ve had enough time to develop tubers. You need to be mindful of the weather being too warm if your cold storage depends on ambient temperature. Cold storage should be less than 10 degrees celsius and ideally around 5 degrees. We like to get all our dahlias chopped down before the first frost so long as temperatures aren’t too warm. We can work most efficiently when the dahlias haven’t been frosted. All of our chopping is done by hand (favourite tool is the cordless reciprocating saw) and all of our lifting/digging is done by hand too.
After the plants have been cut down, we may leave them in the ground for another week or so. We watch the weather forecast and only lift the number of clumps that we can process in a day. The ground protects the tubers from any short term sub-zero temps that will freeze your tubers and from warm temps that might suck the moisture out of your tubers. If you leave clumps of tubers on top of the soil overnight, you may risk freezing them if you’re not paying attention (ask me how I know!).
After you’ve lifted the tubers, you’ll want to keep them cool. Don’t leave them out in the warm sun to “heal” after you’ve cut them. Try to keep them as cool as reasonably possible (think below 10 degrees celsius like your cold storage). Moving them to a shady or cool indoor area to heal can improve your storage success. Never leave tubers directly on concrete because it can suck the moisture out of those beautiful tubers. Cloudy cool days are ideal for lifting/digging and processing dahlia tubers!
I love digging up tubers!!! Its always neat to see how they’ve done over the summer – every variety has a different style of tuber… some are round like apples with no “necks”, some are tiny, some are massive, some are extremely prolific, some have a red or purple pigmentation… fun fun fun!!! More detailed tips for digging and storing here.
