We’ve had a taste of autumn already in September this year, but October is really when sweater season starts. We can still have many warm, or even hot, days, these are balanced by the shorter days and cooler nights. If you are paying attention, you will notice more irrigation water runoff and puddling. You may be noticing new foliage growth, or flowers on plants that have been snoozing for a few months.
PLANTING: October is a busy month for planting. As always, try to plant in the morning. In the vegetable garden, plant chard, spinach, turnips, beets, snow peas, carrots, cilantro, lettuce, and Asian greens from seed. Continue planting seedlings of greens, broccoli, cauliflower, cabbage, and bulb onions.
This month begins the main planting season for most ornamental trees, shrubs, perennials, vines and ground covers. Autumn is the best season to plant some of our favorite California native species like manzanita, California Lilac (Ceanothus), and Silver Bush Lupin (Lupinus albifrons) Have your irrigation system ready before you plant. Those new transplants will need regular water for at least the first two weeks. Don’t plant too deep; for all plants, leave an inch or two of the crown, or center of the plant, above the soil level. The planting hole should be a little wider than the nursery container. Top off with two or three inches of mulch after planting. You do not need to add fertilizer or amendment to the planting hole, but if you insist on fertilizing, use a timed-release granular product. Towards the end of the month, begin to plant spring-blooming bulbs such as daffodils and tulips, or you can wait until November. For bulbs, plant three times as deep as the size of the bulb and don’t over water them.
MAINTAINING: Complete your annual yard clean up, especially if you have planting beds or entire yards based on naturalistic styles. Don’t be afraid to cut those spring-blooming shrubs back to a third their size. Don’t trim deciduous trees yet; we’ll wait until winter for that. Deadhead roses one final time for a fall bloom. Divide perennials and replant. You can replant iris or wait another month. If you can, grind up the plant trimmings and use them as mulch for the garden, or add ground up plant debris to the compost bin. Don’t use any plant material that had disease or pest issues; dispose of them in green waste bins in urban areas and the trash can elsewhere. But any healthy twigs, leaves and old flowers make an excellent mulch in the garden. Use it wherever you can instead of having it hauled to the land fill.
Deep water your trees as they enter dormancy unless we get several nicely spaced storms. Adjust automatic systems to reflect cooler temperatures. In the mountains and foothills, wrap your pipes and remove and store faucet timers before the first frost.
You can apply preemergent herbicide this month to help prevent annual bluegrass, mustard, mallow (cheeseweed), clover and purslane. Don’t apply it where you plan to grow wildflowers or bulbs. Just like with grass species and edibles, we have two main seasons of weeds: warm and cool. We’ve already had some cool season weeds germinating because of the August rain, but in October they really start popping up. Be ready!
This is a good month to check your tree stakes in anticipation of winter winds. If the tree can stand up on its own and the root ball seems secure, remove the stakes completely, and let it bend in a breeze; this will help the trunk gain strength. Stakes should never be right up against the 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 on how to do it properly.
Go easy on the nitrogen-heavy fertilizer as we go into fall, to avoid frost burn of new foliage. This is the season, however, to fertilize your cool-season lawn if you still have one, and lightly feed winter-blooming annuals, perennials, and container plants. Don’t fertilize succulents or cactus.
CONSERVING: Chemical free weed control and plant nutrition is possible. Schedule some time every week or a few times a week to pull or hoe out small weeds as they emerge. Top dress your planting beds and even your lawn with compost. Add another layer of organic mulch to keep your soil healthy. Create healthy soil and your plants will be healthy and more resilient. Mulch, whether organic or inorganic (rock and decomposed granite) also decreases damage to the soil from rain and reduces both wind and water-caused soil erosion. Although we may need to manage many pest insects in the cool of fall, especially in our edible gardens, identify an unknown insect before you kill it or use insecticides. You may be surprised to find you have a wonderful ally in a beneficial insect. In the edible garden, if a plant is overtaken beyond easy control, it is probably best to remove the plant with the pest. Ornamental, non-annuals can usually tolerate some damage and give you the time to solve the challenge. For many disease issues, cultural practices, such as increasing air circulation, weed control and encouraging beneficial insects, should be considered part of the solution.
The cooler weather of October, especially mornings and evenings, means more time to spent out of doors. Many native plants will have a “false spring” display of flowers and new growth. New transplants will thrive. Tree and shrub leaves will show some fall color. Be on the lookout for migrating birds. Enjoy!