Yard & Garden Report


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Loving Your Lawn

Do you want a great lawn? September is the best month to fertilize, kill weeds, aerate and overseed.

Lawn in fallIf you want a great lawn, now is the time to take action.

Early September is the best time to fertilize your lawn. The secret to growing a lush lawn is to develop a thick root system. Your lawn grows most of its roots in fall. Fertilize now to develop more roots.

A soil test can indicate the best fertilizer for your lawn, but a standard winterizer lawn fertilizer (30-0-10 or something similar) works well in most cases.

September is the best time to control perennial weeds (thistle, dandelion and ground ivy). The key to killing these weeds is to get the herbicide down into their roots. In fall, weeds channel their nutrients down into their roots to prepare for winter. If we spray a weed in mid- to late September, it will channel the herbicide (along with its nutrients) down into its roots. Goodbye weed!

The test of a true lawn lover is whether or not they aerate their lawn. I think a lawn receiving an aeration is comparable to a person receiving a massage. Does it feel good? Yes. Do most of us actually need it? Not really.

The vast majority of lawns never need to be aerated, but they all will enjoy it. September is the best time to aerate the lawn. This is when roots grow and aeration promotes new roots. Compacted ground (walkways and heavy soils) and turf with a thick thatch layer (over 1 inch) will benefit most.

Hollow tine or core aerators are recommended because they create air pockets by removing plugs of soil/thatch (cores) from the turf. Let the cores dry for a couple days and then mow to break them up. Remove cores as deep as possible (about three inches) when aerating. Best results are obtained when the soil is slightly moist but not wet. If the soil is dry, irrigate it one or two days before aerating.

You can fertilize after a core aeration to encourage the recovery of the turf. Lawns may be overseeded after aeration, too. Now through mid-September is the best time to overseed a lawn. The ground is warm and the seed will germinate quickly. Weed seedlings are a threat to new sowings, but weeds are less likely to germinate in fall than spring.

Solid tine aerators, spikers and spiked shoes can be used for overseeding but they do a poor job of aerating. They actually compact the ground by pushing soil down when they create their holes.

Vertical mowers (dethatchers) can be used to remove excessive thatch, and September is the best time for dethatching. Try to avoid cutting into the soil with the blades. Rake away the debris. Overseeding can be done to fill in any gaps created by the dethatching.

Written by Tom Kalb, Extension Horticulturist, North Dakota State University. Published in the NDSU Yard & Garden Report, August 31, 2016. The photo was made available under a Creative Commons license specified by the photographer: Timothy Valentine.

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