How to Revive a Weak Lawn

Your lawn might need a little pick-me-up this spring. Photo: Wavebreakmedia, depositphotos

In the spring, it can be a good idea to topdress your lawn to revive it and bring it back to full strength.

By Larry Hodgson

Not happy with the results your lawn gave you last summer? It was yellow, dry, there were insects, dead patches, crabgrass, etc. Where is the green and perfectly even carpet that you had imagined? There’s many a slip between the cup and the lip, isn’t there? It can be a bit discouraging!

But let’s take a closer look. Why do so many homeowners have trouble with their lawns? Drought, insects, weeds, etc. They should be just small everyday complications. They shouldn’t be so devastating. If they are, you have to accept that they are symptoms of a deeper problem. In fact, an underlying one in both senses of the word. Because the problem is simple … the soil in which the grass grows is simply not up to it.

It Takes Good Soil to Grow a Good Lawn!

This is a serious landscaping mistake that unfortunately you see over and over again. Rather than investing in first rate soil that would have provided quality turf for 40 years or more, the installer—whether it was the builder, the developer, or the original home owner—decided to skimp on the quality of the soil.

They installed the turf directly on fill dirt, that is third-grade soil. (The original topsoil is long gone: it’s always carted away when the house is built.) Fill dirt is usually soil recuperated when the foundations were dug, then spread over the yard. Or if they did apply a layer of true soil, they decided to save money by using the cheapest soil they could find. It might well have been “black earth,” which is not even earth at all, but the lowest grade peat. The result is a lawn that seems acceptable for two or three years, then degrades. And then never quite recovers.

3 years of useful life versus 40 years? It’s hard to imagine anyone would go for that, but it seems to be the norm these days!

Do I Have to Redo The Lawn?

Well, yes, sometimes, if the situation is really critical. In that case, a total overhaul is the only logical solution. That would be the case if you calculate that more than half of the grass is either dead or has been replaced by weeds. If so, I suggest you consult the article How to Sow a Low-Maintenance Lawn to find out what to do. But usually you can reinvigorate a weak lawn simply by learning to topdress, then follow that by overseeding!

Topdressing a lawn means covering it with a thin layer of soil or compost. When you apply these products to a lawn, then water it, their particles work their way through the grass blades and thatch and accumulate on the ground. The lawn grasses react to this rich new layer of soil by rooting into it, then grows back with great vigor. Just don’t add too much topsoil at once. You won’t want to choke out any grass that is still healthy.

Typically, you’d apply about 3/8 inch (1 cm) over the entire surface of the lawn if it is clearly weak, but ¼ inch (0.5 cm) may be enough if you judge the lawn to be in fairly good condition.

And then, after topdressing, to densify the lawn, apply fresh, top quality grass seeds. Be sure to look for grass seed that contains endophytes, beneficial fungi that live inside grass plants and help the grass plant better resist insect pests. Grasses containing endophytes also show reduced weed invasion and better summer survival and fall recovery after a drought.

If ever you find the results of your topdressing/oversowing project are not as good as you hoped, repeat next year. (It can sometimes take time to reinvigorate a reluctant soil.) Soon you should see a remarkable difference.

How to Topdress and Oversow

Consider revitalizing a lawn in the spring, when the soil begins to dry out and the lawn begins to green up, or in the fall, as late as about 4 weeks before the ground freezes.

The Preliminaries

Start by weeding. You may lack the patience to remove every single weed, but at least pull out the ones that stick out the most. Yes, you can always spray with a non-selective, broad-spectrum herbicide (weed-killer). There are organic ones, in case you wondered, that do a great job of killing weeds. They’re based on soap, vinegar, citric acid and similar products, so they quickly decompose when their job is done. You just have to apply them directly onto the leaves of the plants you want to kill. Be careful not to spray any grasses you hope to keep: since these herbicides are non-selective, they will kill all green plants.

If your soil is very compact, run an aerator over its surface (available from rental companies). To check to see if this is necessary, try sticking a lead pencil into the ground. If it resists or breaks, the soil is too dense. Otherwise, skip this step.

Do you need to dethatch? In a very dry climate, you may well need to, as thatch tends to build up under dry conditions. But in a more humid climate, dethatching is often a waste of time and effort. In modest quantities, that mixed layer of grasses rhizomes and roots located just above the soil surface, is actually good for lawns. So if it’s under ½ inches (1.25 cm) high, just ignore it.

Do you need to fertilize? I assume that you’re going to buy quality soil for topdressing and if so, no: it has already been enriched with a good fertilizer. If you purchase low-end soil (which doesn’t make sense under the circumstances, since the whole point of this exercise is to improve the quality of the soil!), yes, of course, apply fertilizer just before topdressing.

Now, Start Topdressing!

Now cover the entire surface of the lawn with topsoil. Prefer high-quality soil, such as Golfgreen Enriched Lawn Soil. It’s ideal in helping your lawn to hold on to more moisture and also stimulates faster germination and grass establishment and denser future growth.

If you know your soil quality is especially poor, upgrade to an even richer product with extra fertilizer, such as Golfgreen NitriGROW Lawn Soil, which is especially good on lawns that have given you a lot of trouble in the past.

You can also apply compost, especially if you have a source of high-quality compost. However, be wary of composts that contain mostly peat moss, which is more of a filler than an effective amendment for a stressed lawn. If you want to whip a lawn back into shape, what you need is rich compost!

To spread the soil over the lawn, you can, of course, to rent a soil spreader (topdresser) if your lawn is sizable. Or hire a company to do it. However, topdressing a moderate-sized lawn is actually quite simple. Just empty the bags of soil into well-spaced piles, then rake the soil to the recommended depth with a good leaf rake.

As you rake, add more soil more thickly in any depressions in the lawn and less on any bumps. That way, your lawn will be much more even when you’re done!

Overseeding

Now sow over the freshly applied layer of soil with quality lawn seed. You can also add white clover seeds to this mixture if you wish.

Normally, you need to make two passes with the seed spreader. Set it at half the rate recommended on the seed bag and go over the lawn first in one direction, back and forth. Then, go over the lawn again in the other direction, so at right angles, again back and forth. This will give a more even application (and therefore a more even lawn) than spreading everything in one single direction.

When that’s done, just lightly rake the soil with the leaf rake. That will mix the seeds partly into the soil, covering them somewhat. That way, the birds won’t eat too many of them.

Finish up with a thorough watering using a lawn sprinkler or an irrigation system. That will settle the soil and stimulate germination.

Care of a Freshly Renovated Lawn

For two or three weeks, keep the soil moist. It may need to be watered every two or three days if there is no rain. And avoid walking on the grass.

You’ll see that where the grass was in good shape, it will push through the new layer of soil to take root there; where it was weak, freshly germinated grasses will replace it.

When the grasses reach about 4 inches (10 cm) in height, mow them for the first time (and do so slowly, putting your feet down flat if you can, because the grass roots are still fragile at that stage). A mowing or two later and your lawn will be as beautiful (and perhaps more beautiful!) than a solidly established lawn!

Helpful Hint: Make sure the mower blade is well sharpened. A dull blade will tear the grass rather than cut it neatly and that can lead to uneven growth and disease problems!

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And there you go! A little effort is needed, of course, but topdressing and oversowing will give you a much more robust lawn that will better resist bad weather and pest invasions.

This article was produced with the collaboration of Canadian Tire.