Advice on spring lawn work

By John Fulton

[March 09, 2012]  With the early spring warm-up, there are several complaints about small "hills or mounds" in lawns this spring -- well, we're almost to spring! In most cases, these are caused by earthworms or night crawlers. Unless there is a hole along with the mound. In that case, you may have skunks digging grubs or worms.

It is actually beneficial to have these problems, but sometimes you may not believe it. The worms aerate the lawn, feed on dead material that accumulates at the surface and then deposit the digested material for fertilizer.

If it is so bad you can't walk on the lawn, about the only product that adversely affects earthworms is Sevin (chlorpyrifos). Granules give you a wider window to get rain on an application.

The roughness can be helped by rolling the lawn when it is wet.

Spring lawn care

Spring seeding should be done between March 15 and April 1 for the best chance of success. The reasons for the early date are the heat and the long germination time for Kentucky bluegrass. It can take up to a month for bluegrass seed to germinate. This means an April 1 seeding might germinate May 1. Then add six to eight weeks for it to become established. This could then be close to July 1. Usually we tend to get hot weather about then. Waiting a few years for those fall seedings to take root will probably increase the number of those trying again this spring.

Let's start with the basics. The normal seeding is a blend of Kentucky bluegrass and fine fescue (red or chewings, and not the tall fescue). Some blends also include a perennial ryegrass with the other two species. The fine fescue is much better in shade, and the perennial ryegrass will provide quicker cover.

The seeding rate is generally 4 pounds per 1,000 square feet in bare dirt. Use 2 pounds per 1,000 square feet in overseeding thin lawns. Of course, this can run into some real money when doing very large areas. Many rural seedings are done more on the basis of a pound per 1,000 square feet. An acre is almost 44,000 square feet, so you can do the math on this one.

Fertilizer is always an area of many questions. The place to begin is a soil test. This will tell you where you are starting from. Basic soil test levels for phosphorus, potassium and soil pH should be in the neighborhood of 40, 350 and 6.1, respectively. Phosphorus and potassium are on a pound-per-acre basis. This must be considered if you use labs that report in parts per million, which will give numbers half as large. These numbers will provide a great environment for grass. Grass will grow in very poor conditions, but the lawn certainly won't have that "manicured" look many strive for.

Lacking a soil test, or being at recommended fertility levels, general maintenance applications provide a pound each of nitrogen, phosphorus and potassium per 1,000 square feet of lawn area in May and again in September. Really lush lawns will usually have twice as much nitrogen applied in a season, but split among four applications. Watering is often needed during the summer applications.

Fertilizer prices remain high.

If you decide to try seeding this spring, remember a couple of things related to weedkillers.

First, you can't use crabgrass preventer in the same season as you put down seed. The crabgrass preventer doesn't know the difference between grass seed and weed seeds.

The second rule is to mow the new seeding at least three times before trying any broadleaf weedkiller. Generally this means spring broadleaf control doesn't happen when you seed in the spring. If you seed in the spring, you control weeds in the fall. Seed in the fall, and you control weeds and crabgrass in the spring.

If you do plan to use a crabgrass preventer, time it so it is on about when the forsythia blooms. This would be the approximate soil and air temperature needed for the crabgrass to germinate. April 1 is a good guess, but the date can vary widely with the weather. Many crabgrass preventers last only four to eight weeks, so plan on repeating the application in June anyway.

[By JOHN FULTON, University of Illinois Extension]