Stay on Top of Garden Chores in September
By Sharon Lampton, U. C. Master Gardener
September is the best month to plant perennials, shrubs and trees from containers. You won't have to spend as much time watering. The warm soil will give them enough time to get established before the cold weather sets in. And plants started now will be glorious by spring. As an added bonus, many garden centers are having sales, and sometimes you can get a real bargain.
Plan to put your winter vegetable garden in the sunniest and best draining portion of your garden. Working compost into the soil will improve drainage and also provide good organic matter to help the roots penetrate and grow. You may want to use a test kit to determine the amounts of nitrogen (N), phosphorus (P) and potassium (K) in your soil and amend it as needed.
Sow seeds of peas, carrots, root vegetables, kohlrabi, radishes and fava beans directly in the soil. Start broccoli and cauliflower seeds in containers in a sheltered spot early in the month. They will be ready for planting in about six weeks. You can set out seedlings of broccoli, cauliflower, celery and cabbage now.
Strawberries planted now will produce a crop in the spring.
All tender seedlings and emerging seeds need protection from hot sun and drying winds. Install posts around your beds when you plant seeds. You can easily drape shade cloth over the posts when the days are particularly hot or windy.
Monitor your plants' water needs closely. When the days are cooler, we feel we need to water less, but the winds can have as much of a drying effect as the sun. Only by regularly checking your plants can you determine if you are watering correctly.
Apply nitrogen fertilizer to lawns and immediately irrigate to rejuvenate them. This will be the last application of fertilizer for the year. Late in the month, lower the blade on your lawn mower. De-thatch and aerate your lawn as needed.
September and October are good months for starting new lawns or renovating old ones. The soil should be properly prepared and the irrigation system installed before you plant seed or lay down sod.
Existing lawns can be over-seeded now to correct worn or bald spots. Use a premium grass seed blended for our California cool-season growing area. Detailed reports of turf grass performance are available from the Master Gardener office.
Fertilize permanent flowering plants. Dig in bone meal or a fertilizer such as 0-10-10 to encourage root growth and the formation of next year's buds. Spring-flowering shrubs such as camellias and azaleas need a low-nitrogen product (2-10-10) to keep them healthy and stimulate them to produce strong buds.
Fruit trees, shrubs and groundcovers are still actively growing but should get their last irrigation in September. A late fall feeding (in late September or October) of 10-10-10 fertilizer is suggested just before the plants go dormant. Renew mulch so the soil is shaded completely to prevent fall weed growth.
For flowering plants, sow seeds of sweet peas, forget-me-nots, native wildflowers and Shirley poppies directly in the ground. Set out seedlings of columbine, foxglove, bachelor buttons, lupine, stock, Iceland poppies, pansies, snapdragons, scabiosa, calendulas, ornamental kale and cabbage and violas.
Continue to maintain your fruit and vegetable garden. Collect and compost fallen debris, deadhead flowers, and rake fallen leaves. Harvest fruits and vegetables regularly. Plants slow down when they are carrying mature fruit.
Divide perennials, rhizomes and tubers as needed. Cultivate and amend the soil before replanting them. Cut flowering perennials back to four inches when dividing and transplanting. Don't prune plants while the weather is warm. It could stimulate them to produce new growth that would be killed by frost. You may trim dead or sickly branches out of trees, vines and shrubs.
Most importantly, take time to appreciate your garden this month. The tomatoes taste like sunshine, and many Mediterranean plants will be emerging from dormancy to put on a fall show. Don't work so hard that you forget to enjoy it.