It's long been said that the only certainties in life are death and taxes... and weeds. But it doesn’t have to be that way.
For one, herbicides applied in the spring and fall can help control pesky interlopers in your lawn.
Getting into the weeds
The most problematic spring weeds are crabgrass and goosegrass. They can outcompete the grass in your lawn, eventually killing it off. Putting a pre-emergent herbicide down will help you get ahead of weeds before they take over your lawn. Follow the package instructions to use an appropriate amount for your square footage and apply it when soil temperatures have been at or above 55 degrees for three days.
To see up-to-date soil temperatures by county in Iowa, check the Iowa State Agronomy website. The appropriate temperatures for applying pre-emergent herbicides usually occur between April 15 and May 1.
You may be tempted to go after dandelions in the spring, but you run the risk of damaging other plants by trying to get rid of them after they pop up. Instead, control pesky broadleaf plants — like dandelions — by applying a post-emergent herbicide in the fall, generally mid-September to November.
Looking for a natural option? Although it’s less effective than a chemical herbicide, corn gluten meal is a good substitute for pre- and post-emergent chemical applications. After a few years of repeated use, you’ll see fewer and fewer weeds. Apply 20 pounds per 1,000 square feet of lawn with a drop spreader in the spring and fall.
Find success with fertilizer
Your lawn’s fertilizer needs depend on how green you like your grass and what's lacking in your soil.
Grass needs several mineral nutrient elements to thrive. Most of these elements are available in abundance in the soil, but nitrogen, potassium and phosphorus aren’t always plentiful enough and must be supplemented by fertilizers. Additionally, Iowa tends to have high pH soil and you may require iron to counteract yellowing in your lawn. The best way to find out exactly what you need is with a soil test.
A good rule of (green) thumb is to apply no more than one half pound of nitrogen per 1,000 square feet. Spread it with a drop spreader (not a rotary spreader) when the soil temperatures have consistently been above 50 degrees, usually after May 1. To protect against nitrogen (nitrate) runoff, place buffer strips around your water sources and watch the weather — don’t fertilize if it’s about to rain.
In the fall, apply about three fourths of a pound of nitrogen per 1,000 square feet to your yard. This will help thicken the yard after summer stress and you won’t have to over/interseed with as much grass seed.
DON’T leave fertilizer or pre-emergent on hard surfaces like driveways and sidewalks. It can make its way into storm drains and pollute surface water. If you see this, scoop or sweep the pellets back into the bag or into nearby grass.
Mowing your lawn
The golden rule of mowing is to not remove more than a third of the height of the grass at one time.
For example, if you want your lawn to be two inches tall, cut it when it’s 3 inches tall. When you cut more than a third of the grass’ height, you deplete its carbohydrate reserves and its ability to make food for itself. In the stressful summer months, keep your grass slightly longer (three – four inches) to help encourage deep rooting and to leave more leaf area for photosynthesis.
In the spring, grass has a huge burst of growth, and rain helps this along. If your grass ever gets away from you, don’t mow it all in one go. Raise the mower height up and cut off less than a third of the grass, then a few days later lower the height and mow again to get to your target height.
Watering your lawn
Keeping your grass hydrated is essential. Most Iowa lawns need one to one-and-a-half inches of water per week. It's best to do watering all at once, as frequent sprinklings of water encourage shallow roots, which are less drought resistant.
Watering in the morning — 5 to 9 a.m. — allows the water to soak in to the soil rather than evaporate. If you’ve recently seeded your lawn, water once or twice a day to keep the top inch of soil moist.
Too much or too little moisture can cause problems for your yard. Too much moisture can promote a host of diseases, characterized by brown or white patches. Watering in the morning helps prevent this by discouraging evaporation and a build-up of humidity.
Under drought conditions, it’s best to let your grass go dormant by not watering it and waiting for it to recover on its own. Many gardeners make the mistake of watering a dormant lawn to revive its color, before realizing the water bill is too high. When you bring the grass in and out of dormancy like this you risk killing it off completely.
Improve your lawn with aeration
Aerating your lawn improves gas exchange, root growth and water infiltration in the soil. This is especially helpful for lawns that have been compacted by kids, pets or machinery. Aeration also helps to break down the thatch layer (a mix of dead and living grass) that impedes growth in some lawns.
Most lawns only need to be aerated once in the fall, before early October. However, heavily trampled lawns may need a second aeration in the spring. If your lawn is stressed from summer heat, wait to aerate until it's recovered.
Planting grass
Let’s start from the ground up. When preparing to grow a lawn from scratch, take your time and do it right!
First, fix any major problems in your yard by properly leveling it, addressing drainage concerns (e.g. a lawn that slopes toward your house) and ensuring the surface is as smooth as possible. You only need to rough up the top quarter inch of dirt for the seeds to have good soil contact when you spread them.
Spring may seem like the best time to plant grass because that’s when everything starts to grow. But between cold soil temperatures and competition from annual weeds, seeding in the spring is risky business. For best results, you should plant grass seed in the fall, between Aug. 15 and Sept. 15. The fall is also a great time to establish a native lawn. And be sure to “overseed” or “interseed” your yard to improve its appearance.
If your grass looks patchy after the winter and you simply must seed in the spring, you'll have to wait until the ground is no longer frozen to plant — around early May. Keep the grass well watered and don’t use weed control products, as they’ll kill the new growth.
Planting in the spring is less ideal because seedling grass won’t have much time to establish itself before high summer temperatures set in, so it will likely become stressed, and you could lose more turf than you gain in the long run.
