Killing Weeds – It’s Not What You Think

By: Ryan Such

If you have a lawn, you have probably already realized that you are going to have some type of weeds in your lawn, no matter what you do. However, you do have more control over how many weeds and how often they take to seed.

The 1st step might not be possible for everyone, but is really important if you’re able to make it happen. Make sure you have 6+ inches of good black soil, and make sure that it is not overly compacted because roots won’t be able to flourish in soil that is overly compacted. Some of you are saying, “I already have a lawn and I am past this step. Changing the depth of my soil isn’t an option at this point.” If weeds are a problem for you, the issue might have begun when your lawn was installed. It’s very possible there were some dormant weed seeds in the soil when it was installed. If you are building a home or have a commercial project, you will want to ensure your landscaper puts down 6” of soil and treats it with a non-selective herbicide like Round-Up 7-10 days before seeding or sodding. If you don’t have 6+ inches of soil, that area will dry out faster than other areas of your lawn, causing your lawn to constrict and die off, which leaves open spots for weeds to come in.

This leads into the 2nd step. Keep your lawn as thick and healthy as possible. I realize this is easier said than done, but the single best defense against weeds is simply a thick, healthy lawn. If there aren’t any places for weeds to germinate, they won’t germinate. A thick, healthy lawn will also reduce the frequency and intensity with which you will have to apply chemical weed control. Keeping a thick, healthy lawn can be mostly managed by proper mowing practices, proper watering practices, and occasionally re-furbishing your lawn.

mowing Mowing: Every lawn has to be mowed, and there are proper do’s and don’ts that will help you maintain a thick, healthy lawn. If you’re wondering at which height to mow your lawn, it’s better to err on the side of long/tall. Your root development will tend to correlate to the height you cut your grass. People who tend to cut their lawns too short will see unhealthy root development and will leave their lawns susceptible to drying out more easily, which increases the likelihood of more weeds. Also, do not over “mulch” your grass clippings when you mow. Mulching can be good for your lawn, but not if you cut off too much of the grass at any single time. Trying to mulch long clippings will lead to excess thatch, which will act as a barrier for water and nutrients to reach the root system. If you stay on top of mowing your lawn and don’t cut off more than 1/3 of grass height, then mulching is a good option. If you do not stay on top of it, then you will want to bag it. I always suggest mulching your lawn for the first couple and last couple of mowings each season. Try to mow your lawn at different angles or patterns to avoid spots wearing thin from repetitive traffic, and equally important is to not do “laps” around trees and other objects.
When you are done mowing, it is time to weed eat /trim the areas you could not get with the mower. This trimming should be at the same height as the mowing. The first way people get this wrong is they trim down shorter than they mow. Keep in mind that the edges of your lawn are typically the initial battleground for weeds to get a foothold into your lawn. If those areas are cut too short, then weeds have an easier time gaining a foothold.

Watering: Watering your lawn is another area that is vital for a thick, healthy lawn. I know what you are thinking. Duh! Well, hear me out. Yes, you need to water. If it does not rain and you do not water, it will be difficult to have a thick, healthy lawn. Where most people go wrong, is when they water they water incorrectly. You will hear the experts say you need 1/2 inch to 1 inch of rainfall on your lawn every week. However, that is average! The amount of water your lawn needs depends on your lawn and the time of season. Your lawn does not typically need as much water in May as it does in July because of temperatures. Do you have 6+ inches of black dirt? How low do you cut your lawn? How much shade does your lawn get? How compacted is your soil? All of these things factor in. Here is what you need to take away from the watering section of this blog. When you water your established lawn, water less frequently with longer duration. Do not water every day or every other night. If you water your lawn three times or more a week, you are actually crippling the root system. You are teaching the roots to stay close to the surface because that’s where the water is. You want to have your roots search for water by diving down, but supply enough water so they obviously don’t starve. I have seen too many sodded lawns that are 2 to 4 years old and owner waters three+ times a week and can’t figure out why his lawn still dries out. On these lawns there are spots where the sod can still be pulled up because the roots have never needed to develop.

People ask me, “Ryan, how often do YOU water your lawn?” I water my lawn 8 to 14 times a summer. April and May usually provide enough rain where I only need to water 1 to 2 times during those months. But July and August are the months where I have to water once a week. Keep in mind, though, I have 6+ inches of black dirt, I aerate every year, and I have a deep root system that does not dry out easily. So if you remember anything from this part, it is to water for longer time less frequently.

Refurbishing: A lawn is a living organism. It is actually made up of millions of individual living organisms in the form of individual pieces of grass. Living things die, and when they die in your lawn, if you don’t fill that area in with grass, opportunistic weeds will usually move in. Part of your plan of keeping weeds out of your lawn should be to refurbish your lawn in needed areas through over-seeding or cutting out dead or diseased areas and re-sodding or re-seeding. If you stay on top of this, weeds will struggle to get into your lawn. The two main things you will have to do is keep an eye on trouble areas, especially along the edges of your lawn, and re-seed or re-sod as needed. Also aerating and overseeding can help thicken up an entire lawn because it replaces grass that has died off and caused the lawn to thin out. Many people overlook this step and overlooking it allows weeds to get a foothold and spread throughout your lawn.

If you have a plan to do all of the above-mentioned things well, you may still have some issues with weeds. However, if you do all of them well, your issues will be much less severe. At some point, though, a weed control and fertilizer program will be needed to complement the cultural practices outlined in this article.