Sadly, our need to weed is not yet over. Cooler temperatures will usher in a variety of new weeds. Keeping a clean garden now will pay off in every season. Pull up and compost spent summer annual and vegetable plants. Rake up and compost fallen leaves and debris from under shrubs and trees. By keeping the soil clean, you eliminate many fungal diseases. Yellow jackets are most active during this time of year. Keep your yellow jacket traps clean and loaded with new pheromone cartridges.
- Plants that thrive in fall weather include carrots, beets, broccoli, Swiss chard, kale, arugula and all kinds of salad and Asian greens. Choose varieties that mature quickly, adding an extra two weeks to the days-to-maturity, as listed on the seed packets. This allows for our shorter and cooler fall days.
- After you have harvested one crop, refresh the row or bed with compost and replant with a fall crop.
- Pinch new blossoms and growing tips of melons, squashes, and tomatoes to force growth into fruits that have already set. Any that set from now on won’t ripen sufficiently before cool weather comes. Cherry tomatoes, on the other hand, can be allowed to continue setting, as the little fruits ripen more quickly.
- Deadhead Agapanthus by cutting the stalks at the base. This may actually help to stimulate another flowering stalk this season.
- Rake flower beds, weed, and then replace mulch.
- This is a perfect time to plant wildflower seeds. Weed the area before planting and scratch the surface of the soil so tiny roots can get a foothold. Scatter seeds over the surface, then just barely cover with fresh soil. Water gently to settle the seed in place.
- When winter rains begin, stop watering. (Poppies and lupine are two flowers that do very well in this climate.)
- Winter annuals can also be sowed into the September flower bed.
- In a narrow side yard, or small courtyard, low growing foundation plants (begonias, coleus and impatiens) don’t take up much space and provide a late-season pop of color.
- Feed azaleas and rhododendrons with a high acid fertilizer. Prune lightly only to shape early in September, as they are soon to set their buds for the following year.
- The needles of the mugho pine are a delicacy for the European pine sawfly. Eating only last year’s needles, they will not kill the tree. To beat the pests, remove any needles with rows of yellow eggs on them, now through winter. Their larvae emerge in the spring causing the needles where the eggs were laid to look like curled straw.
- Heat reflected from buildings, driveways and sidewalks may be too hot for nearby maples. Mulching the surface of the soil under the trees keeps the ground cool and prevents fall leaf colors from fading.
- Keep mulch a few inches from the base of tree trunks to avoid fungal or rodent problems.
- Rake up dropped flowers from sasanqua and japonica camellias. Fallen flowers that are allowed to stay on the ground can develop a fungus disease called ‘Blossom Blight’ that will then spread to the plant itself. Blossom blight is identified as unsightly brown edges on the delicate flowers while they are still on the camellia. Also, buds may drop without ever opening.
- September is the perfect time of year to renovate your lawn. One of the key steps is removing thatch so that air, water, and nutrients can reach the root zone.
- De-thatching should be done before the weather gets cool in the fall so the turf has time to recover. De-thatching in more than one direction will cause root damage. Compost the thatch that you pull from the lawn.
- After de-thatching, fertilize, then water deeply.