1. Fertilize trees and shrubs with phosphorus and potassium, but not nitrogen. The root systems of trees and shrubs do most of their growth in the fall. Even when the air temperature cools, the soil remains warm from the summer, which promotes root growth, especially now that leaf growth stops. Phosphorus promotes root growth and potassium strengthens the immune system of plants to give them more resistance to pests, drought and cold. Nitrogen, on the other hand, promotes the growth of leaves and shoots, which is undesirable at present, as a sudden night of cold weather could damage this growth.
2. You can now plant leeks. Depending on the variety, they take two to four months to be ready to harvest, but they can be stored in the ground for several months afterwards. Leeks grow well as long as they don’t freeze except for the occasional frost every few years in the greater Los Angeles area you should have no problems. Occasionally you see young leek plants in the nursery, but you can also start them from seed. To speed up the germination process, get a seedling heat mat for $15-20 from an online vendor. This will make seed germination a much more reliable procedure than when you plant seeds directly in the garden. Place your seeds in Styrofoam or Dixie cups (with holes drilled in the bottom) or six- or four-inch plastic containers, with a plastic or rubber tray underneath. The only caveat is to remove the seedlings soon after germination. Otherwise, they might roast. Plant your leek seedlings in the garden bed spaced six inches apart at a depth that covers the lower white part of the stem. As the plants grow, building up soil around the lower stems will keep them white.
3. When the leaves of deciduous trees turn gold – like those of ash trees, sycamores and sweetgums – treat them as such. Every leaf is a treasure trove of minerals, so plants growing in soil that is always covered with a thick layer of leaf mulch won’t need fertilizing. Remember: we can build and maintain a beneficial layer of mulch around our plants as thick as four inches, so if we are lucky enough to have deciduous trees that provide free leaf mulch, we may as well use it for this purpose. Not only will the soil be enriched with a continuous mineral supply as the mulch breaks down into humus, but water loss through evaporation from the soil will be minimized due to the mulch cover covering it. As a bonus, weeds will rarely, if ever, appear.
4. If you have a plant that has struggled with too much sun (indicated by scorched leaves) or too much shade (indicated by elongated growth and few flowers), now is a good time to move it to a more favorable place. Roots will grow well in soil that is still warm from summer, although the cooler weather means less stress – for plants and gardeners – as soil moisture content is no longer a daily concern. Be sure to dig up a root ball that fully encompasses the root system in the top six inches of soil and most to a depth of one foot. Before you move it – if it’s a shrub or small tree – you may want to wrap the root ball in a burlap tarp (available at lawn mower stores) to make sure it stays intact while moving it to another spot in your garden.
If you’re unsure of the most appropriate exposure for a plant you bring home from the nursery, dig a hole that matches the size of its container, then plant it there, container and all. If the plant thrives where you placed it, remove it from the container and replant it in the hole, but if it flounders, you can comfortably move it elsewhere while still in its container. Before planting, make an assessment of the amount of sunlight available to that spot throughout the year, not just when you plant it.
5. This is the perfect time to plant wildflower seeds for winter and spring flowering. The Theodore Payne Foundation has a collection of 67 different species of California wildflower seeds and the knowledgeable nursery staff will help you choose the best ones for your garden. Seeds germinate more easily in warm soil, making fall a more desirable season to plant them than winter, by which time most of the heat absorbed by the summer sun has dissipated. Make sure mountain garland (Clarkia unguiculata) is one of your native seed choices. The flowers are salmon, pink, magenta, red or purple and consist of four inconspicuous stingray-like petals; double flowers are often found. The distinctive red stems can reach five feet in height. The flowers attract bees, butterflies and hummingbirds and are suitable for vase arrangements.
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