Nov. 11, 2023: Mulching and November tasks

From Linda Gilkeson:

This month’s garden theme is mulch, mulch, mulch…. Fall leaves are the perfect free mulch and with lots of leaves coming down this week, now is the time to collect them. They are ideal for protecting roots of plants in the garden from cold injury. Since we want an insulating effect, the fluffier the mulch, the better, so don’t shred the leaves: even really big maple leaves can be used whole. Right now, start working leaves (or other mulch, such as straw, chopped crop waste) in between plants to cover the soil with a couple of inches of mulch. Don’t cover the foliage though, as hardy vegetables are still growing and need the light. Once in place for a few weeks, wet leaves become matted enough to stay in place during winter winds. If mulching with new straw, which is very light and blows around easily, lay it down just before it rains. To hold fresh leaves or straw in place over a bed you can lay down chickenwire, stucco wire, branches, garden prunings, corn stalks, etc. on top until the mulch is soggy enough to stay put. Also, don’t forget to put a thick layer of mulch on empty garden beds to protect the soil from erosion and prevent weeds from sprouting.

Despite internet myths, all kind of leaves are fine. Oak and arbutus/madrone leaves take longer to break down, but they don’t make the soil more acidic as some fear. Use them alone or mixed with softer leaves, such as apple or willow, to keep the soft leaves from compacting too much. Black walnut leaves (but not other kinds of walnut) may the only ones to be wary of because tomatoes and a few other plants are sensitive to a compound (juglone) from the leaves. Most plants are not sensitive to this and, indeed, some experts are not convinced that black walnut leaves cause significant problems. If you do have black walnut leaves, it is probably a good precaution to compost the leaves to break down the juglone before using them on a food garden.

Keep a pile of leaves aside for the second stage of mulching. With the first forecast of below freezing weather, usually in early December, I do another round of mulching, bulking up any thinner areas and piling mulch over cabbages and well up the stalks of leeks and celery. Also at this time, I pile a very deep layer of mulch right over the top of root crops, entirely covering the foliage and making the bed into a living root cellar. Don’t do this right now as you don’t want to suffocate plants that are still growing. The mulch prevents frost damage to the shoulders of roots, especially those that, like some beets and celeriac, often stick up above the soil surface. Once damaged by frost, the roots rot and attract millipedes and slugs to the decomposing material. There is no need to cut off the leaves of carrots, beets, etc. before mulching. The thick mulch also serves another purpose in the early spring: by excluding light and warmth, it keeps carrots and other roots in the dark (literally!) about the arrival of spring and helps delay the start of spring growth. When overwintered roots start growing again, they sprout side roots and flavours deteriorate as the plants use sugars stored in the roots to grow flower stalks.

Stockpile extra leaves for use next summer. Remember how hard it is to come by mulch materials in the summer? Winter leaf mulches break down pretty quickly in the spring once earthworms, insects, and the myriad of soil micro-organisms have re-awakened from their winter dormancy. By summer there is very little leaf material left to cool the soil and conserve soil moisture; straw does last longer, up to two years before completely disintegrating. The drier the leaves are, the better they will keep without decomposing so try to collect the driest leaves possible for stockpiling. Store them where they will be protected from rain, such as in a wire bin covered with a tarp or in closed leaf bags.

Plan for winter cold snaps [when temperatures drop below -3 to -5 degrees C (23-26 F)]. Hardy vegetables in unheated greenhouses or coldframes are all set, but if you don’t have such structures, stockpile tarps or plastic sheets to use for temporary covers in the garden. Also, collect rocks, bricks, or boards to hold down the tarps. Arctic outbreaks on the coast are usually accompanied by strong outflow winds so heavy weights are needed to keep tarps in place. Since it is too cold for plants to photosynthesize, tarps don’t have to be clear, just waterproof. Lay the tarps directly on plants with reasonably strong stems (such as broccoli, cauliflower). For softer plants, such as leafy greens, you can also lay the tarp over them, however, for better results, putting some kind of support under the covers to prevent plants from being squashed by snow or water accumulating on the tarps. Supports could be low hoops, a row of short blunt stakes, or a length of stucco wire bent into a low arch. Keep the supports low so the covers don’t catch the wind. The wire seed bed covers I originally made to keep birds out (the 1-inch welded wire boxes are 2x4 feet and 6-8 inches high) have been excellent to support plastic over lettuce and spinach beds and were strong enough to hold up a considerable weight of wet snow last winter. Once the cold weather breaks, you can fold up the tarps and put them away until needed again. With an El Niño influenced winter this year, we might not have such severe cold spells as we have had in the couple of years, but given the increasing erratic weather it is best to be prepared for anything.

Pest notes: Climbing cutworms are, as usual, chewing on leafy greens at night. It is well worth a few minutes with a flashlight just after dark for a few evenings looking through lettuce and leafy greens for cutworms. See: Linda Gilkeson | West Coast Gardening | West Coast Gardening: Natural Insect, Weed and Disease Control They are such voracious eaters that one big fat caterpillars can do a lot of damage so you may find that damage stops once after you just find a few. Of course, slugs are going to continue to do chew on plants over the winter too….

Light up your citrus: If you are growing citrus outdoors and haven’t installed winter protection yet, it is time to do that, whether you are using plumbing heat cables or Christmas lights. Lots more notes on this in my November 22, 2022 message Linda Gilkeson || West Coast Gardening || Gardening Tips.

Late sowing: Sowing hardy varieties of lettuce, spinach and other leafy greens so late in the fall that they don’t germinate until early spring has been working well for me for the last few years. I will be scattering seeds for these early crops over an empty bed in the next week or so and will use one of my wire covers to keep birds away from the seeds and to support a sheet of plastic during cold snaps.

Garlic: If you still haven’t planted your garlic, DO it! Planting this month works fine, but don’t put it off any longer….

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.