Overseeding your lawn will thicken the grass, helping it resist future weed invasion. However, it is best used on a lawn where the weeds are currently dormant or have recently been killed. Spreading grass seed on a weedy lawn won’t do much good. Weeds that are actively growing in your grass will steal water and nutrients from grass seedlings, causing them to struggle and die. For best results, attack lawn weeds with a weed killer, then overseed to create a healthy lawn that prevents weeds from returning.
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How Does Overseeding Help Prevent Weeds?
Overseeding your existing lawn with new grass seed fills in bare spots and contributes to thicker grass throughout the lawn. A thick grass lawn without bare spots shades the soil below, depriving weed seedlings of sunlight, killing them. Not only that, but thick growing grass pulls moisture and nutrients from the soil first, before weed seedlings can get to them.
- Overseeding contributes to a thicker lawn.
- Bare spots that have been overseeded with grass are less prone to weed invasion.
- Lawns thickened by overseeding prevent weed seedlings from receiving sunlight and nutrients, smothering them.
- Regular overseeding maintains a thick, weed-resistant lawn without herbicides.
Grass plants, like all plants, weaken and die naturally over time. By overseeding you replenish your lawn with new grass plants. This constant replenishment keeps your entire lawn thick enough that it continues to smother new weeds. This reduces the need to use chemical weed killers on your lawn.
Do You Need to Remove Weeds Before Overseeding?
Overseeding is most effective when you kill existing weeds before you overseed. This is because grass can’t choke out existing, established weeds no matter how thick it is. A lush lawn can only stop new weed seeds from sprouting. Also, any weeds that are present when you overseed will steal water, nutrients, and sunshine from your new grass seedlings. Wipe out the weeds to give your grass a fighting chance.
- Remove existing weeds before you overseed.
- Existing weeds won’t be killed or choked out by overseeding. A thick, overseeded lawn will only suppress new weed growth.
- Kill established weeds or they will rob water and nutrients from your grass seedlings.
You’ll get more new grass sprouts from overseeding if you kill existing weeds first. Overseeding a lawn overgrown with weeds will get a poor yield. Your new grass will struggle to compete with the weeds. Paving the way for new grass by killing weeds is your best bet.
What is the Best Time of Year to Overseed a Weedy Lawn?
For the best results overseeding your lawn, you need to seed at the optimal time for your grass type. Warm-season grass lawns (such as Bermuda, Zoysia, and Centipede grass) should be overseeded in spring. Cool-season grasses (Kentucky Bluegrass, Fescue, Ryegrass) sprout and survive best when overseeded in fall.
- Overseed warm-season grasses in spring.
- Overseed cool-season grasses in fall.
- It’s best to overseed when no weeds are present.
Another factor that makes overseeding in fall a great option for cool-season grass lawns is that few weeds will be present. Even if your lawn was infested with crabgrass in spring, by fall it will have begun to drop its seeds and die off. If you overseed in fall, your new grass will sprout and establish itself. By spring, the grass will be thick enough to prevent many of those crabgrass seeds from sprouting.
What is the Best Grass Seed to Use for Overseeding?
The best grass seed for overseeding is grass that will grow well in your climate. In regions with freezing winters, choose cool-season grass. In regions where winters seldom freeze, warm-season grass will perform best.
- Seed with cool-season grass in regions with freezing winters.
- In regions with mild winters, overseed with warm-season grass.
- Match your grass seed to the variety of grass present in your lawn.
It’s also important to note that overseeding is the act of spreading additional grass seed over an existing lawn. It’s usually best to overseed your lawn with the same species of grass that is present there. This will create a uniform, beautiful lawn.
What Grass Will Choke Out Weeds?
The best grasses for choking out weeds in your lawn depend on your location. If you are planting warm season grass and wish to have a weed-resistant lawn, Bermuda grass is your best choice. It spreads through runners and roots to take over areas, which prevents weeds from getting a toehold.
- Bermuda grass is the best warm-season grass for choking out weeds.
- Kentucky Bluegrass is the top option for battling weeds in cool-season grass lawns.
Kentucky Bluegrass spreads faster than any other cool-season grass. It produces roots that form new plants in both spring and fall, meaning it self-thickens and fills in bare spots. If you want to weedproof your northern lawn, go with KBG.
Will Overseeding Your Lawn Get Rid of Weeds?
Overseeding a weedy lawn will not kill weeds on its own. However, thick grass growth produced by overseeding prevents new weeds from sprouting. In order to keep your lawn weed-free with overseeding, first, kill any existing weeds, then prep your lawn and spread new grass seed. The thick growth of new grass will choke out new weed seedlings as they attempt to sprout.