For Release September 3, 2006

Fall Maintenance for Established Lawns

AGRI-VIEWS

by Chuck Otte, Geary County Extension Agent

We talked about seeding a new lawn or overseeding an existing lawn last week. So what about everyone else who is content with the lawn they have and just want to maintain their lawn? Well, late summer and fall are the times to really get that lawn in shape. How good the lawn looks next spring and summer depends greatly on what you do with it this fall.

The first thing that many people want to do in early September is apply a weed and feed product. Don't! While weed and feed products are very useful, it's actually one of the last things that should be applied. You apply a weed and feed product to kill the little broadleaf weeds that will bloom next spring. With the exception of dandelions, most of these plants haven't started to sprout and grow yet. The weed and feed products have to come into contact with the growing plant. During September and early October these weeds will start to germinate and grow. Apply your weed and feed product in mid to late October.

But there is plenty you can and should be doing during September. As we discussed last week, if you need to reseed or overseed, to thicken up thin lawn areas, do that now. If you want to dethatch or aerate your lawn, you need to do that in early September before you do anything else in your yard, including any seeding activity. Dethatching and core aerating do not have to be done every year, but if you are going to do either operation, do it before proceeding with any other fall lawn maintenance chores.

Sometime in early September, apply a good lawn fertilizer, but without a weed killer. In fact, many of the winterizer products work very well when used in early September. Sure, I know it sounds strange, but it works. What you want to do at this time is to apply a good shot of nitrogen to stimulate that lawn to grow vigorously and strengthen the root system and increase the number of shoots and leaves. If you have a new lawn, less than three years old, in a newer development, you may want to use a high phosphorus fertilizer, like 16-20-0 or 18-46-0, at the rate of about four to five pounds per 1,000 square feet. Many of these new developments have soils that are very low in phosphorus. Established lawns rarely have that problem.

You also want to keep mowing that fescue and bluegrass at the same height that you were mowing all summer. Lowering the mowing height is not recommended because it reduces the amount of food factory, leaves, that are producing food to grow vigorous root systems. There is a direct relationship between the quantity of leaf material and the quantity of roots. If you decrease the leaf mass, you'll decrease the root mass. That's not desirable!

As we move into the latter half of October, you can then treat for the broadleaf weeds. You can do this with a weed and feed product, or just use a straight liquid weed broadleaf herbicide labeled for lawns. If you are using one of these products, then also follow up with a second fertilizer application.

If you overseeded your lawn or are establishing a new lawn, you will want to also treat for weeds and apply a late October fertilization. Make sure that the new grass has gotten large enough so that you've mowed it a couple of times before treating with a broadleaf weed killer. The young grass plants can be damaged by the broadleaf herbicides. If you want that great looking lawn next spring, make sure that you are planning for it this fall!

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