As your garden winds down, think about what you could do differently or better next year. Make your harvest go further by interplanting or intercropping two or more types of vegetables together. This is an intensive method that takes advantage of different maturity rates, heights, spreads, and rooting depths. The classic example is the “three sisters” planting perfected by Native Americans. Corn seeds are sown and two weeks later pole beans are planted at the base of the corn. The beans use the corn stalks as a trellis. When the pole beans are two or three inches tall, winter squash is planted between them, making a living groundcover of squash late in the season. As you plan for fall, think about what to use in an interplanted bed.
- Dig up and store tender bulbs and tubers, such as cannas and dahlias.
- Pick seedpods and heads of open-pollinated flowers to grow again next year; store in a cool, dry spot.
- Plant cool season annuals and ornamentals such as pansies, violas, snapdragons and ornamental cabbage.
- Divide or move perennials that are done blooming, so the roots can reestablish before frost.
- Don’t divide or move plants that thrive in fall, such as asters, mums, Russian sage and ornamental grass.
- Plant spring blooming bulbs in September or early October.
- Leave Christmas cacti outdoors until the night temperatures drop to 40F, so flower buds will develop. As soon as the temperatures drop below 40F, move the cacti indoors to a cool, bright spot.
- Don’t deadhead perennials, biennials and annuals if you want to collect seed (non-hybrids only) or let some self-sow.
- Peonies are best divided and transplanted in late August through September. The “eyes” must not be buried more than an inch or two beneath the soil surface.
- Early in the month, plant spinach for overwintering.
- Look for dry pods on bean plants and save the seeds for planting next season.
- Harvest pumpkins and winter squash before the first heavy frost. Otherwise they can suffer chilling injury that will keep them from storing well.
- Pick winter squashes when the color is fully developed, the rind is hard enough that you can’t dent it with a fingernail, and the stem turns hard and begins to shrivel.
- Harvest lettuce, peas, spinach, and greens as they mature. Many tolerate light frost. Keep them mulched and watered to keep them producing as long as possible.
- There is still time to plant cool weather crops like peas, broccoli, cauliflower, kale, Brussels sprouts, leeks, lettuce, radish and onion. Be ready to protect tender plants from early frost with row covers and blankets.
- As plants finish producing, pull and dispose in your compost pile or city composting facility. Plant the empty spaces with spinach and greens for late fall harvest.
- If you’ve left potatoes and onions in the ground, dig them now and prepare them for storage. Let onions air dry in the open for a few days and then bring them inside to an airy, dry, cool spot. Immediately bring potatoes indoors to a spot where they will receive no light.
- Clean up and remove any fallen fruit. Decaying fruit will harbor pests and disease.
- Young shrubs and trees need regular watering right up until frost. Diminished rainfall in autumn isn’t enough.
- Evergreens especially need lots of water since they keep their needles green all winter.
- If you are planting evergreens, do it now. They should be in the ground by October 1st in order for the fine root system to reestablish itself before the plant goes into partial dormancy for the winter.
- Apply a winterizing fertilizer later in the month to strengthen the lawn before winter without encouraging fast growth.
- De-thatch the lawn every few years in September and aerate if you didn’t in spring.
- This is the ideal time to seed a lawn. Rake the seedbed smooth, add a layer of compost or topsoil if necessary, and broadcast an appropriate grass seed for your area. Apply straw mulch and keep the seeds moist until they have germinated and grown a few inches, watering every day if necessary.