Remove ragweed (Ambrosia artemisifolia) from the landscape by pulling it up by hand or by using a hoe to remove it from cultivated beds. You can also use a broadleaf weed killer if you prefer. Ragweed typically blooms in August and produces a fine pollen that peaks around mid-September causing hay fever (seasonal allergic rhinitis) in millions of Americans.
Ornamental Garden
Begin fall garden cleanup by removing spent annuals and composting them. If a plant is diseased, do not put it in your compost pile. Bag it and dispose of it in the trash instead.
Root stem cuttings of begonias, coleus, geraniums, lantana, and other annuals and overwinter them indoors. This technique works better than trying to overwinter an entire plant, which is not likely to survive the transition indoors.
Bring all houseplants indoors before night-time temperatures drop into the 50s. Inspect the plants carefully for insects such as scale, white fly, mealy bugs, or fungus gnats.
Wipe down all potted plant containers and sauces to remove dirt, debris, spider webs, insect eggs, or larvae. Don’t forget to check the bottom of pots and saucers.
September is the ideal time to divide and transplant spring- and summer-flowering plants such as day lilies, irises, oriental poppies, and garden phlox. This gives the plants enough time to develop a strong root system before the advent of cold weather.
Peonies should also be divided this month or early October. Peony tubers are very fragile, so avoid damaging the root mass as much as possible. Replant the divisions at least 3 feet or more apart and position in the planting hole so that the buds are only one or two inches below the soil surface. If planted any deeper, they may not bloom.
As fall approaches, the cooler temperatures make this an ideal time to plant trees and shrubs. Newly installed woody plants do best when soil temperatures range from 55° F to 75° F. Root development typically stops once soil temperatures drop below 40° F.
Edible Garden
As summer crops such as squash, tomatoes, peppers, and eggplants begin to shut down production, remove spent plants from the garden. Don’t put diseased plant matter in the compost pile.
Sow lettuce seeds every week or two to provide fresh crops until cold weather sets in. Time the last planting so that the crop matures and about two weeks before the first frost.
Sow or transplant cold-tolerant green such as kale, chard, Chinese cabbage, spinach, tatsoi, and arugula.
For a winter crop of carrots, sow seed in early September and keep moist until they sprout. Thing crop as needed.
Cure winter squashes (such as butternut, spaghetti, Hubbard, and pumpkins) once the rind is hard and not easily scratched with a fingernail. Harvest unblemished squash for curing before the night temperatures drop into the 40s and before the first frost. Use pruners to cut the squash from the vine leaving a 2-inch to 3-inch stem attached. Lay the squash in a warm, sunny spot with good air circulation for about two weeks to cure, but move to a protected spot if rain is predicted. Store cured squash in a cool, dry place with good air circulation. Acorn squash does not need to be cured.
As raised beds become empty, sow cover crops such as oats, rye, or red clover to protect the soil.
Lawn
This is the ideal time of the year to reseed and aerate your lawn. Days are warm, but nights are cool. In addition to a higher probability of rain this month, heavy dews provide extra moisture to newly planted grass seed. Moisture is important until grass seeds germinate.
If a soil test indicates a nutrient deficiency, the first half of September is an ideal time to apply fertilizer when grass roots are actively growing. Don’t guess — always apply fertilizer according to soil test recommendations.
While lime can be applied any time of year, fall is generally the best time to apply it because it takes several months to become fully incorporated into the soil. A soil test will recommend how much lime to apply.
A fine layer of organic compost is beneficial to the lawn at this time of year.
