From Linda Gilkeson:
The first spell of really cold weather this winter is forecast to hit the coast later this week as a polar air mass continues to slide over the continent. With long range forecasts predicting -3 to -5oC (23-26oF) starting around Christmas Day and continuing for what might possibly be several weeks, do try to find time in the next day or two to prepare your garden for extreme cold. I know it might not be top of mind this week, what with the covid situation and holiday plans, but a little effort now could make a big difference in how well your winter crops come through. I won’t be sending out notices every time it gets cold, but because this is the first one of the winter, here is a reminder of what to do:
In the next couple of days, while above-ground vegetables are not yet frozen, you might want to harvest enough vegetables to see you through a couple of weeks of bitter cold. Root crops won’t freeze in the soil so can be harvested any time (but it’s no fun digging in freezing weather), however, above-ground veggies should be harvested in the warmer spells, while they are not frozen. If this is your first experience of overwintering crops, you may be wondering about the effects of freezing and thawing. The hardiest crops, such as kale, corn salad, hardiest cabbage and Brussels sprouts varieties, for example, will look pretty much unscathed once they thaw out after a period of sub-zero weather (in fact, Brussels sprouts will be a their sweetest and tastiest, IMHO). Somewhat less hardy plants will have damaged older or outer leaves, but the inner, younger leaves of chard, radicchio, winter lettuce, are usually not injured. If the worst happens, and a very cold spell really clobbers your plants, just leave it and see what grows back from the roots in the spring. If there is snowfall before the cold weather arrives, that provide insulation and plants will fare even better.
What to do now: If you still have leaves or straw on hand, fluff an extra layer of mulch over carrots and other root crops, around leeks and other plants. Throw tarps or plastic sheeting over chard, spinach, Chinese cabbage, lettuce and other leafy greens. Hold the plastic down with rocks, bricks, etc. to keep it in place in windy weather (Arctic outflow winds can be very strong!). You can support the covers on short stakes or low wire hoops, etc., if you want, but keep the covers quite low; you can lay plastic directly on top of plants if necessary and despite some flattening, the plants usually fare remarkably well.
If the cold mass brings us temperatures below -5oC (26oF) (unfortunately, quite possible this year), it would be advisable to also cover winter broccoli, cauliflower and cabbage to minimize damage. Some varieties are hardy to -9oC (16oF) but not all, so try to cover them if you have extra tarps.
A few other things to check: irrigation systems and outdoor taps are drained/insulated as needed; citrus trees and other plants in pots are moved temporarily to a garage or basement for the cold spell (they will be okay in darkness for a week or two).
What’s next? Yay! Tuesday marks the shortest day of the year, a welcome turning point especially for gardeners. Though the daily increase in daylength is only a minute or two per day at first, by early January we will be see noticeably longer days. It won’t be long before we are plotting our next season’s plantings. If you haven’t had a chance to figure out what seeds you need and order them, put that on your post-holiday “do” list (or to cheer you up on a snow day). Seed companies are shipping high volumes of seed orders again this year so try to order as soon as you can.
Gardeners, you gotta love them! As I was glumly leaving the grocery store last weekend, feeling sad about the collapse of family plans due to covid, I ran into a friend who whipped out his phone and proudly showed me a photo of the beautiful Brussels sprouts standing in his garden. It was such a treat! And it helped to remind me that there is a lot to be grateful for, really, so with that… I wish you all the best for the holiday season and for the new [gardening!] year to come.
Republished with permission from Linda Gilkeson’s Gardening Tips. See Linda’s website to sign up for her newsletter, purchase books, access free presentations and identify pests and diseases which may affect West Coast gardens.