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Fix next year’s lawn problems today

Published 10:36am Wednesday, September 5, 2012

by Neil Clark
Southampton County Extension Agent

Want a greener and healthier lawn next spring? Then the time is now to do the prep work.

Weed and thatch control, establishment of new lawns, over-seeding, fertilization and liming should be done over the next few weeks.

DETHATCHING

If you have too much thatch (dead grass and debris), then you should remove this before you worry with applying fertilizers and herbicides as it will absorb the materials and then you will be carrying it away. Hire someone or rent a power rake (vertical mower) to remove the thatch and get to mineral soil.

This is why this should be done in the fall and most often in conjunction with pre-emergent herbicide application; if done in the spring, you are simply creating a fantastic weed bed.

SEEDING

If your goal is to establish a new lawn or over-seed to renovate a struggling lawn, this is also the best time for seeding as the competing weed seeds are more limited. Don’t worry although you don’t see the immediate “green-up” that you do in the spring; remember it is the roots that matter most.

Seeding rates per 1,000 square feet are 2 to 3 pounds for Kentucky bluegrass, 4 to 6 pounds for tall fescue, 3 to 5 pounds for perennial ryegrass and 3 to 5 pounds for fine-leaf fescues. If you desire to shift to a warm-season grass like Bermuda grass or zoysia, you can disregard this article and give me a call next May.

FERTILIZATION

If you only fertilize once a year, the best time to do it is around Labor Day.

Even though spring is when our psyche recognizes all of the greening fresh sprouts, blooms and bud bursts, all of that activity is a result of the release of what is stored up in the fall.

The formation of carbohydrates (energy) in the root systems is what cranks that motor up come spring. Fall is the best time for lawn care.

The first step would be to have a soil test done to learn what, if anything, it needs. It is a good idea to test your soil at least once every three years to determine if supplemental nutrients other than nitrogen are required.

You can pick up a $10 soil test box at the Virginia Cooperative Extension Office in Courtland. The cost of the kit is usually saved by not over applying unnecessary fertilizer, which the plants won’t be able to use and will wash away.

Remember that more is not better, but less may be worse.

In early fall, an N-P-K ratio (stands for nitrogen, phosphorus, potassium) close to 3:1:2 is recommended. The bag will read something like 21-7-14 or 32-8-16.

While phosphorus is a needed element, there is quite a bit of concern about over application and its inclusion will be restricted in Virginia by winter of 2013.

Lawns in sun should receive 1 to 4 pounds per 1,000 square feet of actual nitrogen every year. Lawns and other plants in shade grow slower and don’t need as much nitrogen as plants in full sun. Therefore, shady lawns should be fertilized at half the recommended rate.

For cool-season grasses (fescue, bluegrass, perennial ryegrass), applying one pound of nitrogen per 1,000 square feet in September, October and November will provide the best results if you are applying a quick-release form of nitrogen.

If you put all four pounds down in one application, aside from the possibility of burning up your lawn, the plant will only be able to take up one. Slow release N sources such as WIN or water insoluble nitrogen, sulfur-coated urea, or natural organic N are now readily available and supposedly resolve the need for multiple, small applications.

You don’t want to put out the slow-release granules too much past the end of September, as time is needed to get the nutrients into the plant before they shut down.

LIME

If your lawn needs anything, it is likely to be lime. Most soils in the area are acidic, which lime helps to buffer. A balanced pH will improve the availability of nutrients; encourage thatch decomposition and benefit soil microorganisms, all of which are essential to the soil’s health and fertility. The fall and winter are ideal times to make lime applications since it takes weeks to months to fully realize the benefit of the treatment.

WEED CONTROL

September and October are the best months to control perennial broadleaf weeds like dandelions and chickweed, as well as our area’s most egregious offender, burweed (some around these parts call it sand spur). Although we don’t notice those prickly pests until next spring, they are sprouting and taking hold now, which also makes this the best time to control using pre-emergent herbicides.

Pre-emergent herbicides only work if they are applied to your lawn before the weed’s growth period — this means not later than mid-September around here. There are many pre-emergent products available.

Some of the more common are benefin, pendimethalin, dithiopyr and prodiamine. Follow the label carefully as “the label is the law.”

And if you are too late (and for some weeds you just are anyway) you can come back at the end of September with some trimec combinations of 2,4-D, (MCPA or MCPP) and dicamba for post-emergent weed control.

If all of this is too much time, work, or too complicated, there are a multitude of reputable lawn services that would be glad to assist. That way you can spend more time watching football, grandchildren, or your eyelids.

NEIL CLARK  is the southeast regional forestry extension agent and the unit coordinator at the Southampton Extension office. He can be reached at southamptonextension@vt.edu.

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