Does your lawn look like it’s balding?
Are you tired of looking at patches of dead soil and weak, wispy blades of grass? What’s a turf caretaker to do?
The most common reason lawns become thin and patchy is because of poorly-drained compacted soil. Other reasons may include incorrect species selection, pests and diseases, or poor maintenance habits. A little bit of care can turn a thin patchy lawn back into a lush garden.
Once you’ve identified the problem, the solutions are fairly straightforward. However, it may take an entire growing season to make an observable improvement.
Why is my Lawn Thin & Patchy?
Thin, patchy lawns are the product of poor growing conditions.
There are five fundamental reasons your lawn may be struggling:
- Species selection: you may not have the right turf for your soil/climate
- Compacted soil: your soil may be too dense to promote healthy root growth
- Pests/diseases: your lawn or soil may be infected/infested
- Watering habits: your lawn may be getting too much or too little water
- Mowing habits: you may not be mowing often enough, and you may not be mowing at the correct height
These problems can compound, which can make it difficult to diagnose the root issue.
Your lawn may be thin and patchy because you are growing the wrong species for your climate.
There are two main categories of turf species:
- Warm-season grasses
- Cool-season grasses
Warm-season grasses do not tolerate harsh winters. These turf species are creeping, and they spread with rhizomes and stolons along the soil.
Warm-season grasses tolerate hot temperatures. Some species also tolerate high humidity and salty soils. Warm-season grasses rarely tolerate shade.
Cool-season grasses tolerate harsh winters. These turf species are clumping, and they spread by slowly increasing the size of clumps or bunches of grass.
Cool-season grasses do not tolerate hot temperatures (they may go dormant). Some species tolerate high humidity. There are a few cool-season turf species that tolerate partial or deep shade.
If your lawn is weak when it comes out of dormancy in the spring, or it is easily stressed during the summer, you may be growing the wrong species for your climate.
Compacted soil limits oxygen and water for plant roots, which causes weak, stressed plants.
This is the most common reason for sick, patchy lawns.
Healthy soils have a variety of pore sizes. Large pores hold oxygen and allow water to drain, while small pores hold on to water and nutrients.
Compacted soils have an abundance of small pores, but very few large pores. This leads to poor drainage and oxygen-starved root systems. In severe cases, roots will begin to rot and the lawn will turn a yellow/brown color.
Clay soils are most susceptible to compaction. Clay particles are the smallest soil mineral size, and they tend to stack on top of each other and create thick, solid layers.
If your soil takes days to dry out after a heavy rain, or it is so hard and dry that it won’t take in water, you have compacted clay soil.
Pests and diseases are usually a symptom of an underlying problem.
There are many pests and diseases that create weak, stressed lawns:
- Chinch bugs
- Spring dead spot
- Dollar spot
- Fusarium wilt
- Rhizoctonia large spot
Healthy lawns fight off infections and infestations, but lawns that are already stressed are vulnerable to all kinds of bugs and pathogens.
Although each insect or disease will have identifying symptoms, all pests and pathogens will result in a generally stressed and sickly lawn.
Overwatering is the most common irrigation mistake in lawn care.
All warm-season grasses and most cool-season grasses will go dormant under severe drought conditions. So, even if you don’t water your lawn at all, the odds of severe drought damage are low.
The more common reason for sickly turf is that you water too much, too often, or at the wrong time.
Most turf species require .5”-2” of water per week. This generally translates to 2-3 hours of irrigation divided into two sessions per week.
If you water for 20 minutes each morning, the water will stay in the top few inches of soil, and the grass will grow a thick layer of shallow roots.This results in a weak lawn that will not be able to endure stress.
If you apply more than 2” of water per week, the roots will begin to suffocate and rot.
Of course, it’s possible that you water correctly, and your lawn still shows symptoms of overwatering. In this case, the culprit is compacted soil- not your irrigation technique.
If your lawn is sludgy after watering instead of spongy, you are either applying too much water or you have compacted soil.
Mowing at the wrong height may not put the right amount of stress on the grass.
Mowing is a way to intentionally stress a lawn. Why?
Because when a plant gets stressed, it goes into self-preservation mode.
- Deeper roots
- Thicker clumps
- Vigorous spreading
If you follow the 1/3rd rule of mowing, you will put just enough stress on the lawn to react positively and create a healthier, more vigorous turf.
However, if you cut off too much, the plant will be under too much stress to fully recover.
If you don’t cut off enough, the plant won’t have the stress response to fill in and grow thicker.
If you don’t mow often enough, the grass may get too tall and shade itself out.
If your lawn looks healthy and green, but not as full as you hoped, try adjusting the mowing height and schedule.
How to Fix Thin, Patchy Turf
Once you diagnose the underlying issue (or issues) with your lawn, it’s time to get your hands dirty.
Start with improving watering and mowing habits, and then implement a soil improvement schedule.
You can usually overcome pests, diseases, and even poor species selection if you have a healthy maintenance routine for your lawn.
First, identify the turf species in your lawn. Then, do some research.
Find out what climate zone, soil, and general growing conditions are ideal for this species.
Then, compare the ideal growing requirements to the conditions in your yard.
If they are radically different, it’s time for a complete overhaul.
However, most turf species can overcome slight environmental stressors. If you are only noticing portions of your yard are patchy while the rest is healthy, then focus on small changes.
How to Improve Thin, Patchy Lawns With Overseeding
If your turf species doesn’t tolerate shade, you may notice weak patches of grass under trees or on the north side of the house. Instead of changing the entire lawn, try overseeding with a shade-tolerant variety in these areas.
You may also notice that your lawn is only patchy in areas with high foot traffic. In this case, you can overseed with a more vigorous species to help fill in these areas.
Although some turf species are planted with seeds, others are more successful with plugs or sprigs. Regardless of how you plant the second turf species, the preparation is the same.
Here’s how you do it:
Overseed in the spring or fall, but at least 8 weeks before the first frost.
- Mow the lawn to 1.5” where you want to overseed.
- Use a rake or dethatcher to remove thatch (grass clippings) from the area.
- If the soil is compacted, use a core aerator to aerate the soil.
- Irrigate thoroughly the day before aerating
- Rent a core aerator and adjust the settings for your existing turf species.
- Run the aerator over the area (or the whole lawn- doesn’t hurt).
- Rake .5” of compost over the area (or the entire lawn).
- If you are using seed, use a seed spreader to broadcast seed over the area.
- If you are using sprigs, toss them on the prepared area and space them according to the recommendations.
- If you are using plugs, dig small holes and plant individual plugs according to the recommendations.
- Keep the area uniformly moist for at least 4 weeks.
- Once you notice active growth, back off on the irrigation to once per day.
- When the turf has reached 5”-6”, mow the area and back off on irrigation to a normal schedule.
Remember: when you plant two different turf species, you may end up with one species actively growing while the other is dormant. This doesn’t hurt the lawn, but you may have to adjust your mowing and watering schedule depending on which turf is actively growing.
This is the most likely reason a lawn will be thin and patchy.
Fixing compacted soil is also the best place to start to improve any lawn ailment, because most lawns suffer with a degree of compacted soil.
The goal for fixing compacted soil is to permanently introduce larger pore spaces.
Now, before you take the easy route and mix a dump truck of sand into your soil, I would urge you to reconsider. This is literally the recipe for concrete.
The best way to create long-term, stable pore spaces is by adding compost.
Compost is decomposed organic material. Organic material has a light, spongy texture that can improve drainage and oxygen content in the soil.
Here’s how you add compost to your soil (topdressing):
- Topdress in late spring after you have mowed a few times.
- Mow the lawn to 1.5” or shorter depending on the species.
- Use a dethatcher (or rake) to rake up and remove thatch.
- Irrigate thoroughly the night before.
- Rent a core aerator.
- Aerate the lawn.
- Spread a .5” layer of compost over the lawn area.
- Use a rake to gently push the compost into the holes left by the aerator.
- Repeat each spring.
Over time, the compost will build up a spongy, stable structure that allows water and oxygen to move through the soil. However, if you stop topdressing each spring, the compost will break down (usually over 2-3 years) and the soil will return to the original, compacted clay.
Avoid driving on the lawn, especially while wet, to retain a more porous structure.
Pests and diseases are often symptoms of the core issue.
If the infestation or infection is severe, find a pesticide that treats the issue at hand.
This is not a long-term solution.
Pests and diseases only affect weak or stressed lawns. If you treat the symptom, but not the core issue, you will continue to battle insects and pathogens year after year.
If you have a pest issue, then assume you also have a soil issue. Soil health is the key to plant health. Weak plants = weak soil.
For a long-term solution to pests and diseases:
- Start topdressing each spring
- Mow at the correct height and follow the 1/3rd rule
- Water 1-2 times per week for 1-2 hours in the early morning
Over time, this routine will create a healthy soil structure and a lawn with a deep, fibrous root system. This will make your lawn more resilient during times of stress, which will help prevent future attacks from pests.
There are three reasons you may have an overwatered lawn:
- You water too much/too often
- You live in an extremely wet climate
- You have compacted soil that doesn’t drain
Each problem has a different solution.
- If you water too much/too often, then water less/less often. Look up the water requirements for your turf species. Most species need .5”-2” per week. Divide this into two watering sessions per week, and water early in the morning. Most often, this results in an irrigation schedule of 45 minutes to 1.5 hours two days per week.
- If you live in an extremely wet climate, consider hardscape solutions. As fun as it would be, humans can’t control the weather. If you live in a wet climate and your lawn doesn’t cooperate, try a hardscaping solution:
These structures can help redirect excess water away from your lawn and give the roots room to breathe.
- If you have compacted soil, start topdressing each spring.
Compacted soil drains very slowly, which can lead to symptoms of overwatering even if you water the correct amount.
Follow the instructions for correcting compacted soil to solve this one.
Mowing has an extensive impact on the overall health of a lawn.
Consistent mowing with a clean, sharp blade will encourage deep roots and improve the overall resilience of the grass.
Regardless of the reason for your thin, patchy turf, a proper mowing schedule will enhance the overall look of your lawn.
Follow the 1/3rd rule:
The 1/3rd rule states that you should always remove about 1/3rd of the healthy topgrowth, but never more than 1/3rd of the healthy topgrowth.
This will put enough stress on the plant to encourage new growth, but not so much that the plant is fighting to get back to square one.
Follow the recommendations for your turf species:
Most warm-season species should be cut .5”-2.5”, while most cool-season grasses should be cut 2”-5”.
However, mowing height changes throughout the growing season. In general, cut the grass taller and less frequently in the spring and fall, and shorter and more frequently in the summer.
And there you have it; now you’re fully prepared to tackle any patchy lawn with a receding hairline.
If you’re still not sure what’s causing your lawn to look less than lush, assume the soil is to blame and start by adding compost. Once you have a healthy foundation, the rest of the lawn will fall into place.
For more information on improving soil with poor drainage, visit this article on transforming a boggy yard into a beautiful oasis.