MOBOT's September Gardening Tips
Missouri Botanical Garden
Continue planting evergreens now.
Cuttings of annuals can be taken now to provide vigorous plants for overwintering.
Herbs such as parsley, rosemary, chives, thyme and marjoram can be dug from the garden and placed in pots now for growing indoors this winter.
Except tulips, spring bulbs may be planted as soon as they are available. Tulips should be kept in a cool, dark place and planted in late October.
Begin readying houseplants for winter indoors. Prune back rampant growth and protruding roots. Check for pests and treat if necessary. Houseplants should be brought indoors at least one month before the heat is normally turned on.
Perennials, especially spring bloomers, can be divided now. Enrich the soil with peat moss or compost before replanting.
Divide peonies now. Replant in a sunny site and avoid planting deeply.
Lift gladioli when their leaves yellow. Cure in an airy place until dry before husking.
Poinsettias can be forced into bloom for Christmas if they are moved indoors now to a sunny windowsill. Each night, they must be kept in a cool, dark place where there is no light for 14 hours. This must continue until proper color is achieved in 6-10 weeks.
Cool-season lawns are best fertilized in fall. Make up to 3 applications between now and December. Do not exceed rates recommended by fertilizer manufacturer.
If soils become dry, established lawns should be watered thoroughly to a depth of 4-6 inches.
Begin fall seeding or sodding of cool-season grasses. Seedbeds should be raked, dethatched or core-aerified, fertilized and seeded.
Keep newly planted lawn areas moist, but not wet.
Lawns may be topdressed with compost or milorganite now. This is best done after aerifying.
It is not uncommon to see puffballs in lawn areas at this time. Newly seeded lawns should not be cut until they are at least 2 or 3 inches tall.
Egyptian (top-setting) onions can be divided and replanted now. Sowing seeds of radish, lettuce, spinach and other greens in a cold frame will prolong fall harvests.
Keep broccoli picked regularly to encourage additional production of side shoots.
Pinch out the top of Brussels sprout plants to plump out the developing sprouts.
Harvest herbs now to freeze or dry for winter use.
Tie leaves around cauliflower heads when they are about the size of a golf ball.
Pinch off any young tomatoes that are too small to ripen. This will channel energy into ripening the remaining full-size fruits.
Sow spinach now to overwinter under mulch for spring harvest.
Pick pears before they are fully mature. Store in a cool, dark basement to ripen.
Bury or discard any spoiled fallen fruits.
Paw paws ripen in the woods now.
Check all along peach tree trunks to just below soil line for gummy masses caused by borers. Probe holes with thin wire to puncture borers.
Autumn is a good time to add manure, compost or leaf mold to garden soils for increasing organic matter content.
Monitor plants for spider mite activity. Reduce their numbers by hosing off with a forceful spray of water.
Seasonal loss of inner needles on conifers is normal at this time. It may be especially noticeable on pines.
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