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 notice some new foliage growth, or flowers on plants that have been snoozing for a few months. We are still in a drought, but the change of season allows us to breathe a little easier perhaps: another summer endured, hopefully without too many plant losses.
Planting: October is a busy month for planting. As always, try to plant in the cool mornings and avoid planting if high temperatures are forecast. In the vegetable garden, plant chard, spinach, turnips, beets, snow peas, carrots, cilantro, lettuce and Asian greens from seed. You can also continue to plant seedlings of greens, broccoli, cauliflower, cabbage, and bulb onions.
October begins the big planting season for most ornamental trees, shrubs, perennials, vines and ground covers. Wait until spring for citrus, avocado, and anything else that is frost-sensitive. Planting can happen all month but is especially successful if done later in the month, hopefully after the first good storm. 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 plant’s crown above the soil level. The planting hole should be at least as wide as the nursery container, twice as wide is best. 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 overwater.
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 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.
Deep water your trees a little extra 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. If you’ve been affected by wildfires, install erosion control netting and wattles when it is safe to do so before winter storms.
Preemergent herbicide can be applied, except where you plan to grow wildflowers or bulbs, to help prevent annual bluegrass, mustard, mallow (cheeseweed), clover and purslane. Just like with grass and edibles, we have two main seasons of weeds: warm and cool. October is the month all the cool season weeds 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 tender foliage. This is the season, however, to fertilize cool-season lawns and winter-blooming annuals and perennials.
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. Although adding something from a box or bottle may be quicker, having a healthy balanced garden will in the long run reduce maintenance and improve habitat for a wide range of interesting creatures that won’t harm your garden.
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.
October is a great month to enjoy the garden. 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. Best of all, it is not too hot to get outside and be part of the garden for more than a few short hours a day. Enjoy!
Garden Tips for October Foothills Sun Gazette