Growing Together: September busy month of lawn, garden tasks

Don Kinzler
Forum News Service

Did you hear about the gardening couple who was desperate to find a home for their excess zucchini? After facing rejection from nearly everyone, they wrapped each large zucchini in a cute blanket and left them on people’s doorsteps.

Although some aspects of gardening are winding down a bit, the upcoming month of September is a busy one. If we rank months by yard and garden activity, September is second only to May.

The following is a checklist of September’s lawn and garden tasks:

  • September is the most beneficial month to fertilize a lawn, around Labor Day. Fall fertilizing increases stored energy reserves that makes grass healthier and more disease resistant and promotes a deeper root system, which makes the turf more vigorous next spring and summer.
  • September is a preferred month to dethatch the lawn using a power rake if the lawn has excessive thatch buildup. Thatch is the tan, undecomposed layer above the soil. One-half inch is considered desirable. If the lawn’s soil is compacted, aerating with a core aerator that brings up little plugs of soil can increase air and water penetration.
  • Weed control is more effective in fall than spring because weeds are moving materials downward in preparation for winter and they carry weed-killing herbicide to the roots very efficiently, resulting in better kill. A mid-September herbicide application can help control hard-to-kill weeds like thistle, creeping Charlie, wild violets and others.
  • September is the best month for seeding new lawns or reseeding bare patches in existing lawns. Seeding should be completed by Sept. 15 or Sept. 20 so grass germinates and establishes before winter. Because lawns are long-term investments, skip grass seed bargains and instead choose quality mixes with at least 50 percent Kentucky Bluegrass cultivars. Use blends high in creeping red fescue if the area is shaded.
  • September is a great month for planting trees, shrubs and perennial flowers. Fall root growth gives them a head start versus waiting until next spring.
  • Most pruning should wait until early next spring. Wounds heal slowly in fall, leaving cut twigs open to winter injury. Other than pruning off spent flowers on shrubs like spirea, there’s little or no reason to prune or cut back any shrubs in fall. Wait until spring instead.
  • September is the month to divide, plant or relocate peony, daylily, true lily and bleeding heart. August is best for iris, but September works also. Always water well immediately after replanting.
  • Rhubarb can be divided or moved around Labor Day. Portions of the plant can be dug away with the mother plant remaining in place, or the entire plant can be dug, divided and reset.
  • Garlic, which needs a cold over-wintering treatment, is planted in late September or early October.
  • Bulbs, corms and roots that don’t survive winter outdoors, like gladiolus, caladiums, tuberous begonias and dahlias, should be dug about the time of the first light frost and readied for storage.
  • Hardy spring-flowering bulbs like tulips can be planted now until mid-October. Daffodils must be planted as soon as possible in September. Water well after planting, because bulbs must produce new roots this fall.
  • Cuttings of geraniums and coleus rooted in September can be grown indoors as houseplants all winter and planted outdoors next spring. Root 4-inch cuttings in a mixture of half peat moss and half sand in recycled greenhouse four-packs. Locate in filtered shade outdoors and pot into 4- or 5-inch-diameter pots when they’re rooted in two or three weeks. Move indoors before nights become chilly.
Fielding questions

Question: This hosta problem has been going on for a few years for me. The plants face west and there are four just like this. What’s wrong, and what can be done? — Ron M., Fargo.

Answer: Hosta as a species prefers shade, a cool environment and rich, moist soil. There are some hosta cultivars that will tolerate heat and sun, but they’re an exception.

Your hosta are showing at least two troubles. A west exposure, especially if the hosta are planted close to a building, can be very intense as the hot afternoon sun beats down. Rock mulch tends to accumulate and intensify the heat, which is opposite of hosta’s preferred site. The crispy leaves, yellowed foliage and general weakened appearance are signs of sun and heat stress.

The second situation is the holes in the leaves, caused by slugs, which are a frequent pest of hostas. Slugs work mostly at night, and rock mulch gives them a great hiding spot to slither under during daylight.

What can be done? Relocating the hosta to a cooler, shadier location would help greatly. Spring is the preferred time, but they can be moved now, with great caution. Mulching with shredded bark or wood chips is more hosta-friendly than rock mulch. Slug baits and remedies are available at garden centers, or try the age-old remedy of sinking beer-filled trays into the vicinity around the plants you wish to protect.

Q: I’m a new gardener and I’m wondering when buttercup squash is supposed to be picked. It looks like some of them are getting large enough. — David P., Horace, N.D.

A: Buttercup squash are categorized as “winter squash” along with acorn, butternut, hubbard and others, meaning they store well into winter, as opposed to “summer squash” like zucchini and yellow crookneck, which are eaten when young and tender.

There are several very good indicators that winter squash are fully ripe. Fully mature squash taste better and will store longer than those harvested when not quite ready.

Winter squash can be left in the garden until after the first light frost, down to about 30 degrees. A mature squash loses the glossiness of the skin, and becomes dull in appearance. The “ground spot,” which is the area on which the squash was resting, turns from yellow-green to orange on many varieties, including buttercup. Finally, give the thumbnail test. A mature squash cannot be easily dented with your thumbnail, while an under-ripe squash has a softer rind.

Cut the fruit from the vine, leaving a few inches of stem attached. Field-cure them in place for a week or two in dry, sunny weather. This method will dry and toughen the skin for longer storage. If the weather has turned cold or rainy, you can cure squash indoors in a warm (80-degree), well-ventilated space. Store for the winter in a cool, but not cold place, ideally around 55 degrees, with good air movement.

Q: Several of our houseplants appear to be infested with fruit flies. What is the recommended treatment for this? — Brian A., Fargo.

A: If they are little black flylike insects that flit around the vicinity of the plants, they’re most likely fungus gnats, which are very common. Fungus gnats lay eggs in the soil that hatch into tiny larvae that feed on plant roots and organic material in the soil. The larvae then hatch into gnats, which lay more eggs, creating a continual life cycle of gnats, eggs, larvae and more gnats.

Don’t laugh, but there’s a good product for fungus gnat control called Mosquito Bits. On the label, it also indicates it controls fungus gnats.

Sprinkle the granules on the soil surface, following label directions. The product, which is an organic insecticide, breaks the life cycle of the gnats. It usually takes a little time to work, but is effective long term. I’ve seen the product sold at garden centers, hardware stores, farm supply stores and national chains.

Select high-quality grass seed containing at least 50% Kentucky Bluegrass cultivars.
September is a good month to add trees, shrubs and perennials to your landscapes.
A reader wonders what might be causing these hosta problems.