Spring grass seeding         

By John Fulton

[MARCH 14, 2006]  With moisture falling around the county in the past week, many may be willing to gamble on trying to establish some grass from seed. Along with seeding, timing in the spring is critical for some additional operations. Let's start with crabgrass control. Crabgrass is an annual grass, meaning it comes up from seed every year. One of the best ways to control annual weeds is to use a seed germination inhibitor that works on that germinating seed. The only problem is timing. These herbicides must be put on before you see the weed -- in this case, the crabgrass.

Many of the germination inhibitors are combined with fertilizer. They should be applied about April 1 in our area, but the timing can vary a couple of weeks. The crabgrass seed germinates on the basis of soil temperature, and soil temperatures need to be about 55 degrees for seven to 10 consecutive days. Without a soil thermometer and a continuing log of soil temperatures, one of the good indicators is forsythia in bloom. If you don't have your crabgrass preventer on by the time you see forsythia blooms, you had best get it on quickly. Another thing to keep in mind is that the same product that prevents crabgrass from germinating will do the same thing to other seeds. This means that you can't sow new grass seed and use a crabgrass treatment at the same time of year. If you need seeding done, fall seeding is actually the best.

Grass may be sown either March 15 to April 1 or Aug. 15 to Sept. 10. Spring seedings don't usually have the success that the fall ones do, because hot weather tends to hit before lawns become well established. Last fall was an exception, when the dry fall actually had seed lying dormant for months. Seeding rates should be about 4 pounds of seed per 1,000 square feet for bare dirt and half that rate for over-seeding thin areas. We recommend using a blend of grasses such as Kentucky bluegrass, a fine fescue and perennial ryegrass. You can actually buy the seed pre-mixed from retailers. Some people leave out the perennial ryegrass, but it does provide quicker germination and some durability.

The seeding times are also good times to use a plug aerator or a power dethatcher. These operations are very hard on grass, and doing them when the grass recovers quickly goes a long way to keeping your lawn healthy. Both of these operations are usually done to help remove thatch layers. This thatch should be no more than one-half inch in depth, or you'll tend to have disease problems come in.

Fertilizer and broadleaf weed control are best applied in May when they work better. This early in the season, lawn weeds aren't actively growing, and turf isn't growing actively enough to make good use of nitrogen fertilizer. Many broadleaf weed killers need temperatures over 50 degrees to work properly.

Another item I am getting several calls on is grubs and moles. The two are often related. Moles eat grubs and earthworms for food.

This really isn't a good time to try to control grubs, since they are large in size and won't be around too much longer. They will pupate this spring and come back out as June bugs, Japanese beetles or green June bugs to start the process all over again. The best control time is from August through September.

Mole control is best accomplished by doing away with their food source, so they go elsewhere. Since newer grub controls don't result in the same reduction of earthworms as diazinon did, insecticide treatments may not eliminate enough of the food source to be effective. Also, with this not being a good time for grub control anyway, you are reduced to trapping for moles. The loop-type and scissor-type traps seem to work better than the harpoon traps.

Hopefully these spring lawn tips will get you started on the right track for the year. If you have further questions, feel free to contact the office at 732-8289.

[John Fulton, unit leader, University of Illinois Extension, Logan County Unit]

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