Your Labor Day yard and garden task checklist

Gardening columnist Don Kinzler says early September is the time to fertilize lawns, divide or relocate some perennials and getting ready for fall.

Geranium cuttings rooted in early September will be ready for next spring's outdoor pots and planters.
Michael Vosburg / The Forum
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FARGO — Did you hear about the guy who contemplated going on the almond diet, where you eat nothing but almonds? His doctor advised against it, saying the diet was just plain nuts.

Luckily, area diets are made healthier by the wholesome food that’s plentiful in area gardens in late summer. Besides picking tomatoes and other produce, the Labor Day weekend is a busy time for other tasks around the yard and garden.

Crowded iris plants can be dug and divided in August or early September.
Michael Vosburg / The Forum

The following is a checklist of early September lawn and garden projects:

  • Research has shown that early September is the most beneficial time to fertilize lawns, as grass plants are building strength, developing deeper roots and filling out horizontally, which makes the lawn healthier and thicker for the upcoming year. Applying lawn fertilizer around Labor Day gives grass the nutrition it needs, preferably using fertilizer labeled as a fall-type or “winterizer” which has extra nutrients for root growth.
  • If lawns are thin or patchy, consider overseeding between Labor Day and Sept. 15. Rake, power rake or core aerate, and spread seed. Keeping the surface consistently moist with daily or twice-daily light sprinklings is the key to successful grass seed growth.
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  • Spot-spray weeds in September with liquid herbicide. Fall is the best time to control weeds, especially hard-to-control types like thistle and creeping Charlie. Granular weed-and-feed products are generally less effective at weed control than liquid herbicides.
  • Geraniums propagate readily from cuttings this time of year. If cuttings are taken now, rooted in a mixture of peat moss and vermiculite, potted up and grown indoors during winter, they’ll be ready for spring’s outdoor pots and planters.
  • Around Labor Day is the time to divide or relocate peony, daylily, true lily and bleeding heart. Crowded iris can be dug and divided anytime from August through early September.
Iris clumps can be divided with a sharp knife or pruning shears.
Michael Vosburg / The Forum
A fan-shaped iris division is ready for replanting.
Michael Vosburg / The Forum


  • Rhubarb can be divided or moved in September. Portions of the plant can be dug from the perimeter with the mother plant remaining in place, or the entire plant can be dug and divided. For best results, add organic materials like compost, peat moss or manure when replanting.
  • To develop a new garden spot for next year where lawn currently exists, skip a mowing, then spray with glyphosate, which is the active ingredient in original Roundup and other brands. Roto-till or spade after about two weeks. Alternatively, smother the grass with layers of cardboard or black plastic in preparation for next spring.
  • Bring tropical plants back indoors for winter growth before night temperatures dip consistently too far below 50 degrees Fahrenheit, such as hibiscus, mandevilla and any houseplants that vacationed outdoors. Wash them outside with a gentle stream of water and consider treating with insecticidal soap or similar insecticide.
  • Purchasing and transporting houseplants now while the weather is mild is easier than during winter’s frigid temperatures.
  • Apple harvest dates depend on the cultivar, as some ripen in August, some in September and late types are better left on the tree until after frost. Ripe apples begin dropping, have a background color that is yellow and less green and the seeds of a ripe apple have turned from light tan to shiny blackish-brown.
  • Harvest potatoes when vines have died and the skins are firm and not easily rubbed off. They can remain in the ground for a month or more after the vines have begun to die.
  • Onions are best harvested when most of the tops have fallen over, and the necks are entirely withered and dry. Cure in shallow trays in a warm garage for several weeks before removing the dry tops, with most of the dry “wrapper” leaves left intact.
  • Squash can remain in the garden until frost has collapsed the vines. Mature squash fruit have lost the immature glossy skin tone and the skin is solid and not easily punctured with a thumbnail. For best eating quality, buttercup-type squash should be cured after harvest for two to four weeks at about 80 degrees in a warm garage. The flavor and sweetness of many squash types increases in storage, and is best after at least one month.
Don Kinzler, a lifelong gardener, is the horticulturist with North Dakota State University Extension for Cass County. Readers can reach him at
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