The recent snow melt and warm temperatures gets folks in the mood to start spring yard chores. With all the spring chores needing to be done, lawn care sometimes takes a back seat in priority. This is actually a good thing because initiating lawn care too early can be the source of problems later in the season. This is especially true if the lawn needs compaction relief or dethatching. The two operations to correct these problems aeration and power raking are best done in the fall. However, if these problems are serious enough to prevent turf grass cultural practices from being effective, then carrying out either or both operations in the spring, once the grass has begun active growth, usually early May, is acceptable.
Thatch only becomes a problem when it accumulates in excess beyond inch in thickness. Thick thatch may be soft and springy to walk on, but it predisposes the lawn to poor water, fertilizer and pesticide utilization, makes it vulnerable to drought, and the roots do not penetrate deeply (if at all!) into the soil below. Other problems, such as diseases and scalping when mowing, eventually will prompt the homeowner to do something about it.
Dethatching should be done when the soil is moist. You usually can rent a machine for this purpose. Stay away from lawn mower attachments that advertise dethatching capabilities as they are often destructive to the lawn and mower. Usually fertilizer, and sometimes crabgrass control or reseeding, is carried out after the dethatching is completed.
Thatch or not, most lawns would benefit from an annual aeration. This is especially true where the turf areas are growing in clay soils. The pulled cores can remain to gradually disintegrate or be raked out or broken up with a power rake. Because the root zone then has an abundance of air, the grass plants will be able to more effectively take up water and nutrients.
Dead spots- Dead spots or thin areas in your lawn can be repaired by replanting specific areas or inter seeding the whole lawn. Bluegrass seed is typically used when correcting these problems. If these areas are shady, creeping red fescue will yield better results.
When replanting the dead spots or inter seeding your lawn, just work the soil slightly with a garden rake. Spread the grass seed over the area and rake into the soil gently. Be careful not to damage the existing grass if you're inter seeding. If thick thatch creates a seeding problem, use a garden rake to remove some of it. Thatch will serve as a barrier against moisture evaporation and as a mulch for protecting the new grass seedlings. The replanted areas must be kept moist until the grass seed has germinated and become established.
Fertilizer- Try to wait until the soil warms up and the grass is actively growing before applying spring fertilizer. The general recommendation is to do spring lawn fertilizer applications in mid-late May around Memorial Day. Another fall application can be made about Labor Day. When you fertilize your lawn don't apply more than one pound of actual nitrogen per 1000 square feet at one time. This would be five pounds of 20-10-5 fertilizer or three pounds of 34-0-0 fertilizer. The three numbers indicate the percentage of nitrogen, phosphorous and potassium. Lawn fertilizer should normally have at least 20 percent nitrogen. Don't fertilize your lawn in mid-summer. Use a fertilizer spreader to apply fertilizer. You'll be much happier with the results. Don't apply fertilizer to damp grass. Apply to dry grass and then water it in thoroughly. This washes the fertilizer off the leaf blades without burning them. Areas which you have replanted or inter seeded should not be fertilized until early fall. Fertilizer tends to damage germinating grass seeds and young grass seedlings.
Snow Mold - Snow mold is created by a heavy mix of compacted snow over the lawn creating an area between the grass and snow that generates a humid and snow mold environment. You will especially find snow mold in areas that snowblowers threw or others areas of compacted snow. These areas do need special attention as snow mold can be a very severe problem to the point of killing the grass. Snow mold creates an area where a fine web looking area covers the grass and actually pushes the grass down to the ground creating an environment that does not allow any air to penetrate the grass surface. This high humidity area does not allow sun penetration and 99% of the time the grass will die, however in some instances grass will recover from snow mold it will just be thinner which can give weeds a chance to invade. If the crown is killed, the turf will need to be re-established. The best way to do this is to rake the area and remove any dead grass. Then apply about 2 pounds of Nitrogen per 1000 sq/ft and 1-2 pounds of grass per 1000 sq/ft. and lightly rake or harrow the area if large to help incorporate the seed and nitrogen into the soil surface.
What should be done to control snow mold in the lawn?- Once most of the snow has melted away, go out and spread the rest of the snow out to encourage a faster melt. If the grass seems to be matted down go out with a fan type rake and fluff up the grass. This will cause the area to dry out and warm up quicker. If this is done the grass will usually recover from snow mold.
Can anything be done in the fall to prevent Snow Mold?- No, not really! Applying a fungicide in the fall of the year would be a total waste of money. Cutting your lawn at the normal height in the fall and spreading out slow melting snow banks in the spring of the year are your best bet.
The last thing I want to mention is white grubs. If you have small areas that look dead (2-4 feet in diameter) you might want to check for white grubs. The best way to tell if you have white grubs is to grab onto the dead grass and if you can lift the grass and soil slightly you very likely have white grubs. Sevin works very well in controlling white grubs. If you have further questions please either, stop by the Extension office or call 701-776-6234 ext. 5. I will either answer your question over the phone or if it sounds like something I need to look at I will come and take a look.
Schmidt is the Pierce County agent for the NDSU Extension Service.