Let the planting season begin! Unlike gardeners in different climates, autumn, not spring, is the very best season to do the majority of planting, transplanting and moving soil. Exceptions: high mountain gardeners have a better season in spring. And frost tender sub-tropical plants, such as bougainvillea, citrus and palms should not be planted until spring. But for the majority of valley and foothill gardeners, and for a majority of plants, October is the perfect month to get outside and get things done.
TREES, SHRUBS, and PERENNIALS: There are hundreds of climate-right plants, native and not, to choose from. Be aware of nursery labels and tags; instead do your research using a reliable source like WUCOLS (http://ucanr.edu/sites/WUCOLS/Plant_Search/) or the Sunset Western Gardening Book for things like heat and frost tolerance and water use. Our warmer winters recently have encouraged many of us to plant desert-origin species, which is fine, but remember we could still get some significant frost nights that can damage plants that are rated zone 10-12. Sometimes the damage is not evident until the following spring. We've been fortunate with two decent precipitation-full winters, but it is still the best practice to transition your landscape to one that requires less water and less maintenance.
WINTER ANNUALS: Sow seeds of Clarkia, California poppies and other wildflowers. Sweet peas can also be started now. Soak seeds overnight before planting. They need a trellis unless you are planting the knee-high variety, or let them ramble through shrubs or along a fence.
VEGETABLES: Plant beets, collards, carrots, kohlrabi, kale, leeks, lettuce, spinach, onions and peas from seed, or purchase transplants at nurseries. We continue to see better heirloom availability of both seeds and transplants, which can be fun to try if you or your family are adventurous. Having kids help with the choosing and planting will make them more apt to try eating something new. But remember, most heirlooms lack the disease resistance that has been bred into hybrid varieties, so sometimes they take more monitoring and care.
WATER WISELY: Nights are growing cooler, so lower the frequency of your watering. Make sure to deep water all trees until they are dormant. As in all seasons, water your trees around the edges of the leaf canopy, not at the trunk. Continue to water until the rains arrive, then plan to shut off your irrigation system until spring, using water only if we have an extended dry winter period.
WEEDS: Just as we get a handle on summer weeds, cool-season weeds start to appear. Preemergent herbicide can be applied, except where you have seeded for wildflowers or other plants. Preemergents help prevent annual bluegrass, mustard, mallow (cheeseweed), clover and purslane. Use compost and mulch to suppress weeds. Use mechanical methods (hands and tools) to remove those that do emerge when they are still small.
COMPOST: Think twice about putting any plant with seeds or pest problems into your compost bin. Most home compost systems do not get hot enough to kill seeds.
MULCH: Replenish your mulch if you can see bare dirt through it. Or consider planting a "living mulch," a.ka. ground cover plants. Inorganic mulch (rock, gravel) has grown in popularity and has the same water-saving and weed suppressing functions as organic mulch, but remember the effect rock mulches will have on non-heat-loving plants next summer.
FERTILIZE: Fescue lawns and non-native perennials will benefit from an application of fertilizer to promote fall growth. Do not fertilize frost-tender plants; the new growth will be susceptible to frost damage this winter. Fertilizer is not recommended for most California native plants in the ground, but you can fertilize your container-grown plants once a year.
PRUNE: Cut back perennials if they are finished blooming. Hedges and other evergreen shrubs can be clipped to their desired size and shape. Finish garden clean-up chores while the weather is pleasant.
STAKE: This is a good month to check your tree stakes. If the tree can stand up on its own, remove the stakes completely, and let it gently bend in a breeze; this will help the trunk gain strength. Stakes should never be right up against the tree trunk. Those stakes are for transporting from the nursery, not long-term. If you need to stake a tree, we have information on our website (see below) on how to do it properly.
When you're done with October chores, go ahead and add one more plant to the garden.