September is a lovely month of warm days and cooling nights. While the soil is warm for good root growth, and with rain in the offing over the next couple of months, it is a great time to set out trees, shrubs, perennials and lawns. Keep up with weeding and cleanup, but enjoy your time in the garden in this season of beauty and bounty.
- Keep watering if there is no rain. Vegetables need an inch a week.
- Pull plants past their season, such as green beans and squash, to make room for fall crops of cabbage, kale, turnips, carrots, onions and garlic.
- Seed many cool weather crops directly in the garden: carrots, turnips, chard, beets and spinach.
- Sow clover, rye or cowpeas as winter cover crops in areas you aren’t using for fall crops. Turn under the green manure in early spring.
- Mulch new transplants well to prevent weeds and preserve water.
- Pick fruits that are coming ripe. Keep windfalls cleared and pick in the evening to avoid problems with wasps.
- Sow seeds of Sweet William, English daisies, stock and snapdragons.
- Start roots of peonies for next spring’s blooms. Put in well-drained, loose soil and don’t plant deeply—just an inch or so beneath the surface. These big-bloomers like morning sun with some afternoon shade. If you have peonies that need dividing, do that now.
- Divide hostas, daylilies and monkey grass while there’s enough warm weather to encourage root growth.
- Plant spring blooming bulbs, digging plenty of organic matter into beds. Plant ground cover, such as ajuga, over them to disguise the fading foliage after blooming.
- Continue to divide iris. Cut off and dispose of leaves with aphid damage. Replant iris rhizomes so they’re slightly exposed at the soil surface.
- Dead head perennials that have passed their blooming season, cut off browned foliage and neaten beds. Shear lavender early this month; you may get more blossoms.
- Replace mulch under rose bushes to prevent disease next spring.
- Sow fescue and cool weather perennial grasses. For fescue, use 6 pounds of seed per 1,000 square feet. Fertilize existing fescue.
- If you water your lawn, do it deeply (1 inch) once a week, not every day. Short, frequent watering encourages shallow roots, which leads to disease and little drought tolerance.
Trees and Shrubs
- Start planning and ordering shrubs and trees for fall planting. It’s not too early to set out container-grown shrubs and trees if you keep them watered until the rains come.