October 2: Planting garlic, winter mulching, powdery mildews

From Linda Gilkeson:

September this year was certainly a far cry from the cool, wet month we had last year. After being away for a couple of weeks I was surprised to come back to such warm weather, but happy to have the extra warm days making up for the late start to summer this year.

Garlic: Top of mind garden task this month is planting garlic, which is best done in October. You can pretty much plant garlic any time in the fall, but believe it or not, it is best to wait until the soil is cold and wet. Planting while the soil is still warm and dry as it is right now can increase the risk of infection with Blue Mold Rot (Penicillium spp.). This fungus is short-lived in the soil and thrives in dry soil at soil temperatures of 22-25oC [71-77oF]. It is well managed by good sanitation (crop rotation, planting only healthy cloves) and by waiting to plant until the soil is cold and wet. If you have already planted garlic, tough, don’t worry about it!

If you prepare the beds now, before the soil become too soggy to handle, you will be all ready to plant when the rains start. Amend the soil with lime to raise the pH if your soil is acidic and incorporate a generous supply of finished compost. A complete organic fertilizer might be called for to increase fertility in new gardens and in beds where the previous crops didn’t grow as well as expected. Lightly comb the amendments into the top layer of soil and wait for colder, wetter weather to pop the cloves into the beds, then cover with mulch.

Collect leaves: Another key task this month is collecting fallen leaves for winter mulching and to stockpile for next summer’s mulch. Usually, the first leaves I rake in the fall are dry so I set aside a good supply for use next summer. Leaves don’t decompose if they are kept dry over winter under some kind of cover or in big plastic bags. Leaves that have been rained on can go straight onto the garden as they are brought home. Start mulching around the base of plants and cover the surface of any beds that don’t have crops. Try for a layer of dry leaves 15 cm/6 inches deep everywhere; this will pack down somewhat with rainfall and as they winter wears on. Keep aside some mulch to use in late November or early December to cover over the tops of carrots, beets and other root crops. That late in the year the plants will have stopped growing so don’t need to see the sun. Piling a thick mulch right over the whole bed makes a living root cellar out of it and protects the roots from freezing no matter how cold it gets.

Any kind of leaves are fine to use as mulch, with the exception of black walnut, which should be composted before being used on a garden (some plants are sensitive to compounds in black walnut; there is no problem with English walnut). For some reason internet rumours persist that bigleaf maple leaves or oak leaves or Arbutus/Madrone leaves are bad for gardens, but ignore such advice. For winter mulching, keep leaves whole. They break down more slowly, provide better insulation against cold and protection again erosion from rainfall. When you want leaves to disappear into the soil system quickly, shredding or mowing helps, but that is not what we want to happen with winter mulches. Where fall leaves aren’t available, any coarse organic material works for mulching: straw (expensive, but an excellent mulch), crop debris that is dry and fibrous (e.g., shredded corn stalks, dry bean and pea plants), even bracken ferns, prunings from flower beds and shrubs, etc.

Many people have been wondering whether it is OK to mulch with leaves of bigleaf maple infected with powdery mildew. On some trees, the leaves looked nearly white this year due to the fungus, but despite this, it is fine to use the leaves for mulching or to make compost. The fungus that causes this mildew doesn’t infect other maples species or other kinds of trees and plants. Especially for people with dust allergies or asthma, however, it might be a good idea to use one of those face masks we all have these days to avoid breathing in spores while raking up mildew-y maple leaves.

Powdery Mildews: After the prolonged dry weather, powdery mildews have been showing up on Swiss chard, kale and other plants that you might not expect to have mildew infections. Infected leaves have a fine whitish dusting more or less evenly spread over the surface; it is usually most obvious on oldest leaves. These are different species of fungi than the powdery mildew commonly seen on squash and cucumbers at this time of year. Like other powdery mildews, the fungi will stop spreading when the rains start and leaves become too wet for spores to germinate. I don’t harvest infected leaves to eat, but I do retain them on the plants so they can continue to feed the roots. There is no need to get rid of infected leaves or remove the plants because new leaves that sprout later in the fall or in the spring won’t be infected. It is a good idea to keep track of varieties that seem to have the worst mildew infections (or other problems) so you can avoid the most susceptible varieties in future. For example, I am going to quit growing “Bright Lights” chard as it always seems to be infected first and worst when we are having a season with a lot of powdery mildew about.

Reminders for overwintering crops:

-If you haven’t done it yet, go out today and pinch out the tips of Brussels sprout plants (and kalettes, too) to force growth of the sprouts this month. [Kalettes are a cross between Br. sprouts and kale that make little rosettes of leaves along the plant stems, where sprouts would be on a Br. sprout plant)

-Continue to keep carrots covered with insect netting until the end of October or until after the first hard frost. With this warm fall, adult carrot rust flies are still active and laying eggs.

-If your garden crops have been chewed on by rats this year, see my October 12, 2021 message about controlling them: Linda Gilkeson || West Coast Gardening || Gardening Tips

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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.