What To Do in the Garden in September & October
Planting spring flowering bulbs
AUTUMN GARDENING CHORES
Remove, pick up, and discard any diseased plants or leaves. Disinfect your pruners as you move from plant to plant to prevent spreading fungal spores, bacteria, phytoplasma, and viruses.
Divide early-summer–blooming perennials that have become overgrown, show diminished bloom, or have a bare spot in the clump center (doughnut). Do this in early fall while there is still enough time for the roots to settle in for the winter.
Deadhead (cut off the flower/seed heads) plants that seed freely unless you want seedlings. This will cut down on your weeding next year. Leave the seed heads of astilbe, black-eyed-Susan, coneflower, and daisies intact to provide food for birds and winter interest.
Remove weeds to prevent both perennial and annual weeds from getting a head start in the spring.
Add compost to your beds to improve soil texture and promote beneficial microbes to prepare the garden for next spring.
Spread fallen leaves to serve as a protective mulch for your plants.
Don’t heavily prune trees or shrubs at this time. Pruning now may prevent hardening off and encourage new growth that can be killed back during the winter.
Don’t prune lavender, azaleas, viburnums, rhododendrons, forsythias, or spiraea.
BULBS, TUBERS, AND CORMS
Plant spring flowering bulbs from mid-September through October to allow bulbs to set strong roots—resulting in more successful blooms.
It’s difficult to tell the top from the bottom of some bulbs. The skin is loose at the top and attached at the bottom. If you can’t tell, plant them sideways.
To deter moles, voles, and squirrels, ring the planting area with a mixture of soil and gravel or put small chicken wire between the bulbs and soil surface.
Plant bulbs two-to-three times as deep as their height, or a little deeper for naturalizing varieties.
Dig and store summer-blooming tubers such as caladium and elephant ear before frost and tuberous begonias, cannas, and dahlias after the foliage is blackened by frost.
FRUITS – VEGETABLES – HERBS
Pot up some of your garden herbs and bring them in the house for fresh herbs during the winter.
Cover plants if early frost is expected.
Harvest frost-tender veggies and herbs such as basil, tomatoes, beans, peppers, eggplants, squash, and pumpkins.
Don’t wait too long before picking pears—they ripen from the inside out. Take a fruit in your hand and tilt it horizontally. If the fruit comes off the branch it is time to pick your pears.
Cut off the growing tip of each tomato stem to prevent new flowering. The energy will then go into the tomatoes already on the vine.
Continue watering into the autumn so developing vegetables such as tomatoes and peppers mature.
Allow winter squash such as butternut and acorn to fully ripen on the vine. The rind will be hard and not easily punctured. Harvest before the frost.
Harvest onions when the bulbs are mature and the tops start to turn yellow. Store in a dry place.
Plant radishes, kale and spinach for your last crops of the season.
Plant your largest garlic cloves around Columbus Day about three inches deep.
Plant cover crops or spread composted manure or compost over unplanted areas.
Mulch carrot rows for winter harvesting.
LAWNS
September is the best time to fertilize your lawn or seed a new one. Remember to water newly seeded areas regularly to keep the soil moist. Choose high quality seed appropriate for your site.
Overseed bare spots in the lawn. Filling in bare spots helps prevent weeds in those areas next year.
Check your lawn for grubs by lifting up about one square foot of sod. If there are more than 10–12 grubs per foot you may want to treat the lawn.
GENERAL
Don’t spread mulch until the ground freezes.
Trees, shrubs or any newly planted perennials should be kept well-watered until the soil freezes.
In late September, bring in any houseplants that have been outside or annuals you want to winter over. Give the foliage a good soapy bath and check them carefully for insects. Keep them isolated from your other houseplants for two to three weeks. Do this is before you have to turn on the furnace. This cuts down on the shock of moving inside.
Harvest sunflowers when the seeds are firm. (Cover with mesh if birds are a problem.) Cut the heads with about a foot of stem. Hang in a dry area to complete seed ripening.
Watch out for Asian ladybugs, stink bugs and western conifer seed bugs that enter homes looking for warmth and shelter. Caulking and weather stripping helps prevent their entry. They are not harmful and can be vacuumed up. Empty the vacuum bag to dispose of them.
This is the time for fall webworm (Hyphantria cunea). Spraying is not necessary. Consider hosing down the webs to disturb the cycle.
Take pictures of your gardens. Make notes for next year’s gardens now—what worked, what didn’t; what to add, remove, or move. You think you will remember next year, but you won’t!
Plant winter pansies, ornamental kale, and mums. In October bring some pumpkins and gourds to the landscape for seasonal interest.
—Lyn Chimera and Carol Ann Harlos, Erie County Master Gardeners
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