Even if you only know me casually, you’ve probably caught on that I’m a bit of a plant geek… I mean, more than just the roses, tomatoes and squash. In fact, my real expertise (at my day job) is regarding perennials. I’ve learned a lot there about how to grow each crop to finish for sales in the spring, but the trickiest growing is on those crops I have to tend through the winter.
I made a quick video about it:
When it really comes down to it, the tricks to successfully overwintering any hardy plant in a container are pretty similar:
- Start with clean plants – remove dead and diseased foliage early to avoid later problems
- Protect them from cold winds that would dry their tissues
- Shelter from the coldest temperatures. For some of the less hardy plants, this may mean heating – but for many perennials in the mild winter climate of the Fraser Valley, this just means a layer of protection (snow, crop cover, or an unheated greenhouse)
- Try not to let your greenhouse heat up during sunny days
- Provide decent air circulation
- Don’t keep the plants wet all the time, but do water ahead of the coldest weather to prevent desiccation
- Even if you start with clean plants, do inspect them frequently for any signs of disease or rot. As foliage dies down, in most cases, it’s advantageous to trim it away from the plant
And because this is a website about roses, I’ll add this: while I don’t recommend much winter pruning for roses in the landscape, I perform a moderate pruning on the container roses in my greenhouses. Where they have a little protection, they tolerate the winter pruning fairly well – I combine the pruning with stripping off the old foliage. This sanitation protects from winter rot, but also gives new foliage in the spring a fresh start, with no old leaves to carry over black spot or powdery mildew.
And here I am, enjoying a sunny January day in our garden! The days have been getting longer since December 21 – but I recently heard a climatologist quote a different measure: the dead of winter, which sounds more ominous than the way he explained it. The dead of winter, measured by local weather history, is the point in the year when your area has the very lowest average temperature. Every day after that is statistically more likely to be warm. I can buy into that! Here in the Fraser Valley, it’s around January 4th.
So we’re over the hump. As a rule of thumb for me, I begin seeing my greenhouse plants wake up around Valentine’s day. There’s still a lot of winter that can happen in a month, but it’s nice to have the finish line in sight.