Jennifer Schultz Nelson
Extension Educator, Horticulture
Everyone wants to be the person with the yard that greens up first on the block each spring. But what many people don't realize is that the best way to achieve the first green lawn is to begin spring lawn care in the fall.
The grasses typically grown in lawns in this area such as Kentucky bluegrass, perennial ryegrass and fescue grow best in cool weather. A little extra TLC in late summer gives lawns a chance to develop a strong root system over the cool fall and late winter months as well as the spring months. A few extra months of good growth in cool weather helps build a turf more resilient to the heat of summer.
But all is not lost if you didn't start your lawn care in the fall. There is still a lot you can do this spring to be on your way to a great looking lawn.
Although your first inclination may be to fertilize your lawn heavily in early spring to achieve that coveted first green lawn on the block, that is a really poor choice in the long run. Excessive nitrogen application, more than about ¼ pound of nitrogen per 1,000 square feet, will encourage shoot (green) growth at the expense of root growth.
This results in turf that is very green and lush, but does not have a strong root system supporting it. This turf is likely to be very stressed and difficult to maintain without tons of water once summer heats up.
Apply a full application of fertilizer around Mother's Day only if you intend to water your lawn throughout the summer. Consider using slow- or time-release fertilizers that slowly release nutrients to the grass over the course of the season, rather than one big dose all at once. Keep in mind that pushing shoot growth with lots of nitrogen may create a weaker grass blade that is more prone to disease.
The major weed that can be controlled in the spring is actually a summer problem. If crabgrass was an issue in your lawn last summer, spring is the perfect time to attack it and head off a crisis this summer.
To chemically control crabgrass, the recommended method is pre-emergence herbicides applied in the spring. These are typically included in the "spring" lawn fertilizers. You may also find them as separate stand-alone products-- this is really the best choice, as "spring" fertilizers tend to be too heavy on the nitrogen.
Pre-emergence herbicides are typically applied in granular form with a spreader. These herbicides work on the germinating seeds in the soil, disrupting key enzymes in the germination process, and the seeds never germinate.
The timing of pre-emergent herbicide application for crabgrass is crucial. Crabgrass seed will only germinate after soil temperatures reach 50 to 60 degrees Fahrenheit for several consecutive days. There is some disagreement in the specific temperature and time period depending on the information source used. Nonetheless, if you apply a pre-emergent herbicide after the crabgrass seed in your lawn has germinated, you have just wasted your time and money. Pre-emergent herbicides will not affect seedlings. It must be in the soil before the crabgrass germinates.
So when should you put down your pre-emergent herbicide? The bag in our garage says February through April- not a very specific timeframe. One source I found says that the average date of crabgrass seed germination for central Illinois is between April 20 and 23rd during a year of "normal" weather, and pre-emergent herbicides should be applied at least two weeks prior. While more specific, I challenge you to tell me what "normal" weather is around here!
The best advice I can give is to keep an eye on the weather, and if you are really ambitious, track the soil temperature too. When the weather warms consistently, put your pre-emergent herbicide out. One source I found said to apply pre-emergent herbicides when the local Forsythia blooms are wilting. The good news is that pre-emergence herbicides do stick around in the soil for four to six weeks, so if you're a little off in your timing, it will still work.
If you are trying to seed a new lawn or over seed an existing lawn this spring, do not put down pre-emergent herbicides, or none of your desirable grass seed will germinate. The best strategy is to start a new lawn or over seed an existing lawn in the late summer or fall, get it growing well, and then you can apply pre-emergent herbicide in the spring without an issue.
Seeding lawns should be done as soon as possible in the spring. Seeding past mid-April is almost too late. In order for the new grass seedlings to survive the hot summer, they need enough time to grow in the cool spring to develop a healthy root system. Late seeding will germinate, but realize that the new grass may not make it through summer's heat.
Whether you are seeding a new lawn or overseeding an existing lawn to fill in some thin or bare spots, it is crucial that the grass seed has good soil contact. If you just scatter seed on top of existing turf, it is very likely that the seed will just sit on top of the grass or thatch and not touch soil. Without soil contact, the seed will not germinate. Use a garden rake to scratch the seed into the soil after broadcasting seed.
If you are seeding a large area, it may be worth your time and effort to rent a slit seeder, which is essentially a machine that makes little slits in the soil beneath your lawn and drops seed directly into these slits. My husband had difficultly getting anything but weeds to grow on the lot we purchased next door to our home until he used a slit seeder. Good soil contact made all the difference in getting grass to grow over there.
Once you have your beautiful lawn green, lush and growing, remember to mow as soon as the grass needs it in the spring. Most lawns should be mowed to a height of 2 to 2 ½ inches or more. Mowing too short may stress the turf, and taller turf will help conserve water and suppress weed growth. Do not mow wet turf-- this may spread disease in your lawn. Sharpen mower blades at least once a year, ideally twice a year; a dull blade will rip rather than cut, which makes for a shabby looking lawn, and may promote disease development.
I'll admit I'm not the "lawn ranger" at my house-- this is my husband's territory. This time of year he starts to chomp at the bit when it comes to working on the lawn. Most likely you will find him spreading crabgrass preventer on our yard in the near future..