September 2012 To Do List, Zone 7
It still feels like summer out there. In Zone 7 it can often stay hot until October in the South. Nonetheless, it’s time to think about fall and winter garden tasks, like setting out kohl crops and hardy herbs, planting trees and shrubs, as well as spring flowering bulbs. You’ll start seeing bulbs on sale now. Buy them, but don’t plant until October or November. Keep them cool and dry in the meantime.
In the Pacific Northwest, September is a lovely month with warm days and rapidly 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.
In all parts of Zone 7, September is a month of flowers. Fall wildflowers begin their bloom while some of the summer bloomers are still putting on a show. Ornamental grasses begin to show off their blowzy seed heads and many roses enjoy a second flush of blooms. So even though the chores of weeding and cleanup continue, they do so in a time of beauty and bounty.
- Keep watering vegetables that are still producing. Remember the inch-a-week rule if there is no rain. You can set up an irrigation system to help water your plants.
- Pull out any plants that are past their season, such as green beans, corn and squash to make room for fall/winter crops. Put anything that isn’t diseased or full of seeds in the compost. Rake aside mulch to use again or replenish with fresh mulch, and start planting those fall crops.
Seed cool weather plants in the ground now, such as chard, turnips. mustard, spinach, beets, carrots, lettuce. You can also plant another round of potatoes to mature as the weather turns cool (but make sure you get them out of the ground before a hard freeze!).
- Now is also a great time to plant garlic.
- Sow clover, rye or cow peas as winter cover crops in areas you won’t be using for fall vegetables. These plants will fix nitrogen in the soil and can be tilled in as green manure come spring.
- Set out plants seeded earlier indoors. Mulch new seedlings of broccoli, cauliflower and collards well to preserve moisture and help them grow to size before cold weather. Try a row cover to keep the late summer bugs off the new plants and to shade them a little from the hot sun.
- Pick fruits that are coming ripe now such as apples and plums. Keep windfalls cleared away to avoid problems with wasps. Pick in the evening to avoid the wasps buzzing around the trees.
- Flare-ups of spider mites have been reported during dry weather, on tomatoes and other vegetable crops. Spider mites are tiny, and often overlooked or misdiagnosed as a disease. Infested leaves have fine webbing on the leaf undersides. Tomato leaves damaged by spider mites usually have yellow blotches, while bean leaves show white stipples from mite feeding. Pumpkins can tolerate moderate levels of mites, but watermelons are more sensitive to injury from mite feeding. Mites have many natural enemies, such as lacewings, ladybugs and pirate bugs, but these helpful predators are often killed by pesticides. If white flies have been a problem in the vegetable garden, you may elect to put your seedlings out in October after they are gone, or place seedlings under a floating row cover.
- Set out hardy herbs now: chives, sage, mint, tarragon, and rosemary. Keep the plants pinched back as long as the weather is warm so they won’t go to seed.
- Sow seeds of Sweet William, English daisies, stock and snapdragons.
- September is a good time to start roots of peonies for next spring’s blooms. Make sure to put in well-drained, loose soil and don’t plant deeply—just an inch or so beneath the surface. Choose early-blooming varieties that do better in summer heat if you are in the South. These big-bloomers like morning sun with some shade in the afternoon. If you already have peonies that need dividing, do that now.
- Divide hostas, daylilies and monkey grass while there’s enough warm weather to encourage root growth.
- In the Northwest, plant bulbs now. In the South, wait for October.
- Continue to divide iris not taken care of in August. Examine leaves for aphid damage. If it exists, cut the leaves & dispose of them. (When finished with this task, clean tools with alcohol or a diluted chlorine bleach solution.) Make sure that when you are transplanting your iris rhizomes, that they are not planted too deeply. The rhizomes should be slightly exposed at the soil surface.
- Dead head perennials that have passed their blooming season, cut off browned foliage and neaten beds for fall. If you shear lavender early in the month, you may catch another round of blossoms.
- Replace mulch under rose bushes. You’ll prevent disease next spring.
- In the South, summer’s lovely orange blooms from the butterfly weed will now begin to display their showy, silky seedpods. A native perennial, it can thrive in poor soils. Though they do not transplant easily, the butterfly weed is a prolific self-seeder. (You may want to pick the seed pods before they take over available real estate and share them with friends.)
- With light dead heading, you may be able to stretch the blooming of your coreopsis through the fall.
- Sow winter rye grass over Bermuda or carpet grasses to get winter green. 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 lead 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 if you keep them watered until the rains come.
- In the South, wait to plant trees until October. In the Northwest, do it now.
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