From Linda Gilkeson:
After the warm winter so far, below freezing temperatures are now in the forecast for our first bit of colder weather this winter. Starting Friday this week and continuing for a few days, forecasts range from one or two degrees below freezing overnight for the Victoria area to -4 to -5oC overnight further up Vancouver Island, for Vancouver and other Lower Mainland areas. At higher elevations or further inland, overnight temperatures tend to be lower so some of you may have lower temperatures overnight in your garden. It doesn’t look like severe or prolonged cold is likely for now, so preparations this week should just ensure that everything is well mulched and possibly that the least hardy vegetables are covered. But first, you might want to harvest a batch of carrots and other roots, leeks, a cabbage, lots of leafy greens, to store in the refrigerator for use in over the next few weeks. Root crops and cabbages, in particular, keep well for weeks in the fridge if you have the space to store them.
With the warmth and heavy rain this winter, I notice that leaf mulches applied last fall have packed down and are half-way decomposed already, therefore I am adding another layer of leaves to previously mulched beds. I have also finally spread a thick covering layer of leaves right over the tops of carrots and beets. The thick mulch protects the shoulders of the roots from getting frosted and turns the bed into a living refrigerator. Hardy lettuce, celery, spinach, chard and other greens should be OK to about -5oC (23oF) with just the usual mulch around plants. If lower overnight temperatures are forecast, it would be a good precaution to cover the beds with a tarp or plastic sheet. It is only when it is likely to drop to -8 or -9oC [15-17oF] overnight, that it is advisable to throw a tarp over winter broccoli and cauliflower, cabbages and leeks. Plants survive best with an insulating cover of snow, but the forecast temperatures for this weekend shouldn’t be damaging for hardy vegetables even without snow cover. For more details on cold-proofing a food garden in colder weather, see my November 25, 2022 message: Linda Gilkeson || West Coast Gardening || Gardening Tips
Pesticide rant warning! This week I was horrified to read a newsletter from a well-known seed company promoting “Top 10 Hacks” for pest control that focused on several homemade concoctions to spray on plants. The idea that the primary way to control pests is to spray something is an outdated misconception (SO last century!). I thought idea had had died out by now, but clearly not! So, although it isn’t the season to worry about pests other than slugs and rats, I thought I would mention the problems with using such sprays now. Over the coming growing season I will try to include more information in my newsletters on better ways to deal with common pests in home gardens.
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The first problem is that any substance that kills or repels “pests”, will do the same to non-target and beneficial insects, mites and other organisms. Since most of the insects and mites that live in our gardens are not pests and many are directly beneficial (pollinating flowers, attacking leaf-eating or sucking insects, etc.), spraying a pesticide in the environment where they also live is a bad idea. Most homemade sprays are less toxic to people and less persistent in the environment than some commercial pesticides that were available for sale to home gardeners before 2016—but, the fact remains that if a homemade spray works on pests, using it has the same drawbacks as using any pesticides. (In 2016, pesticide legislation in BC was changed to limit what home gardeners can buy or use to a small list of least-toxic commercial products).
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If a homemade concoction doesn’t work on insects (most don’t), that still doesn’t mean it is harmless. Even non-toxic sprays change the “odor” of leaves detected by beneficial insects. This can cause changes in their behaviour, such as avoiding previously treated leaves. I saw this effect first-hand in research I did in the 1980’s on a native aphid predator. I found that female aphid predatory midges would not lay eggs on leaves that has been sprayed with soap or pyrethrins several weeks earlier, even after aphids had returned to feed on those leaves. An unseen effect of sprays is that they can also disrupt the naturally occurring community of fungi and bacteria that should be present on leaves. Among other benefits, these microorganisms prevent plant pathogens from being able to infect leaves–so harming them obviously isn’t a good idea.
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Some homemade sprays can also damage the leaf cuticle on plants, burn leaves or even kill delicate or young plants, especially when made from chemicals such as dish soap, detergents, oils, alcohol, baking soda, etc.
SO bottom line: Let’s scrap the idea that there is any such thing as a “safe” spray, one that can control a pest or disease without negative effects. Occasionally, limited use of a pesticide as a last resort may be justified (iron phosphate slug bait comes to mind) but home gardeners have other, far more effective ways to deal with pest insects.
Gardening tips archive: Just a reminder, especially for new subscribers, that all of these messages are archived on my web site at: Linda Gilkeson || West Coast Gardening || Gardening Tips
You might want to look back at other messages at same time of year because I don’t cover the same things for every month. For example, right now you might want to read the January 20, 2023 message on how to do a simple germination test to check whether old vegetable seeds are still good for the coming season.
PLEASE do not reply to this message (I won’t see your message and it may be automatically rejected by the listserv). To subscribe, unsubscribe, or send me a message, contact me: info@lindagilkeson.ca
See my web site for hundreds of photos of pests, beneficial insects, diseases and disorders to help you identify problems. Also, under the Presentations menu, there are pdfs of talks on growing vegetable seedlings, saving seeds, climate resilient gardens, the issue of global loss of insects and even one on how to identify coastal butterflies.
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.