Clean up dropped fruit and fallen leaves from fruit trees; compost if healthy. Discard any diseased fruit and leaves. Cover any bare soil in your garden. Spread an organic mulch like wood chips to build up your soil structure and protect plants from heaving over the winter.
In Northern California:
Plant cool-season annuals such as African daisy, Iceland poppy, larkspur, lobelia, pansy, petunia, phlox, snapdragon, stock, sweet alyssum, sweet pea, and viola. Water them frequently, especially during hot spells. Fertilize and water your roses, but do not prune them yet.
If you live in a frost-free region, October is a great time to plant cool-weather flowers and vegetables in your garden. Crops such as kale, cabbage, collards, lettuce, carrots, mustard, onions, Brussels sprouts, cauliflower, beets, and garlic can all be planted in early to late October.
Also, do not cut back hardy perennials like garden mums (Chrysanthemum spp.), anise hyssop (Agastache foeniculum), red-hot poker (Kniphofia uvaria), and Montauk daisy (Nipponanthemum nipponicum). Leave the foliage. It's important to protect the root crowns over winter.
To prevent the disease from returning the following year, we suggest cutting the plants back in the fall and removing any debris – no matter the variety! It will give your plants a clean start next season. *Destroy any foliage with symptoms of powdery mildew and disinfect pruners before trimming other plants.
You can still expect some warm weather during October, so keep watering the garden until the fall and winter rains begin. As temperatures drop, less water is needed for plants. Check your soil periodically by digging gently into the soil next to the root, about 6 inches down (deeper for bigger plants).
Leafy greens and Brassicas: Lettuces, spinach, and Swiss chard can be planted from seed or from transplant this month. Plant members of the Brassica family, including broccoli, cabbage, Brussels sprouts, kale, kohlrabi, and cauliflower, from transplant. Kale can also be planted from seed in October.
To support plants through this season of transition, make sure they get adequate water until the ground freezes. This is especially important if the summer season has been hot and dry, and for newly planted trees, shrubs and perennials. In fall, plants do not need as much water as they may have needed in summer.
When To Stop Watering Plants in Fall. When the air and soil temperatures consistently fall below 40 F, it's time to stop watering. The ground can't absorb water once the top few inches freeze. Continue to water your plants up until this point so they're as well-hydrated as possible going into winter.
What to add? Compost, raw organic matter, and organic nutrients. Autumn is a good time to improve your soil by adding raw organic matter, such as shredded leaves.
Yes, leaves make excellent mulch. Add a few inches of leaves to your garden beds in fall and leave them there for the winter. As time passes, the leaves slowly decompose, gradually adding nutrients to the soil.
Preparing for a Fall Vegetable Garden
Although many vegetables grow and mature well into the fall, most need to be started before the nights turn cold. In climates with early frost dates, your fall garden will need to be started in mid-summer from late July through August.
September and October are prime months to plant perennial plants that are not frost tender. It's not too late to plant fall vegetables and herbs. Vegetable starts for cool season vegetables continue to be in great supply.
To ensure a successful fall and winter harvest, you need to start many of your late-season crops in the peak of summer. In most regions, this means planting in the heat of August to give your crops time to size up while growing conditions are still good.
The best time to water plants is in the morning or evening.
Morning watering is actually preferable to evening watering as the plant has time to dry before the sun goes down. At night, water tends to rest in the soil, around the roots, and on the foliage, which encourages rot, fungal growth, and insects.
Early morning (5:00 to 9:00 am) is the best time to water the garden when using a sprinkler, garden hose, or any other device that wets the plant foliage. When watering is completed, the plant foliage dries quickly. The rapid drying of plant foliage helps guard against the development of fungal diseases.
The best time to water outdoor plants is in the morning when temperatures are usually cooler. This gives the plants time to absorb the water so they can get through a long, hot day. The second-best time is late in the afternoon or early in the evening. Try not to water at night.
Fertilizing in the fall helps plants be hardier when the temperatures drop. We also recommend applying fertilizer in the late fall, toward the end of October or early November. This application will catalyze one last frenzy of root growth and really give your plants some staying power through the cold months.
But when should hostas be cut back? Hostas should be cut back in late fall. Healthy hosta leaves can be left on the plant in early fall to capture much-needed energy, but all leaves should be trimmed off after the first frost to deter slugs and other pests from making your hosta their winter home.