Moss is soft, fast-growing, and can completely overtake a lawn in just a few weeks. While many prize a natural moss-covered lawn and will spend time and money to cultivate one, even more people want to know how to get rid of moss on their lawns. Often, this process involves reseeding a moss-covered lawn. Below is how to do it and how to make this the last time you need to reseed your lawn because of moss overgrowth.
Firstly – Can You Grow Grass on Top of Moss? (The Short Answer)
While you can grow grass on top of moss, those grass seedlings will not grow well unless the conditions causing the moss to grow have been resolved. If your lawn is covered in moss and deep shade with a thick layer or decomposing plant matter underfoot, your reseeding will do little to grow a lush lawn.
The Challenges of Reseeding a Moss-Covered Lawn
A moss-covered lawn did not get that way overnight. Moss is particular about the conditions under which it will grow. The greatest challenge when it comes to growing grass on top of or in a moss-covered area is that the moss will likely out-compete the grass unless the overall conditions that make the moss want to be there are resolved.
If you leave things as they are, the following challenges will remain and your grass will ultimately be out-competed and die back.
The Right Grass Type is Critical for a Moss-Prone Lawn
If you choose to seed over the existing moss and use the same type of grass that already exists in your lawn, you are choosing to back a losing horse.
Some grass types, such as fine-bladed Zoysia cultivars in warm climates or fine fescue and perennial ryegrass in cool climates, can make do with as little as 3 hours of dappled sun each day. However, no grass can grow in near complete darkness, but moss can. If this is what you’re dealing with, you’ll need to improve light levels before selecting a grass type.
Low Fertility Causes Grass to Falter and Moss to Flourish
Moss can thrive on minimal nutrients compared to grass, especially if you mow your lawn frequently. If you are planning on reseeding a moss-covered lawn, you will either need to fertilize at the same time or before planting your grass seeds.
If you do not and nutrient levels are low, the moss has an advantage while your newly planted grass seeds will likely grow slowly and, in the case of low light conditions, damp off or falter – ultimately dying within the first 4 weeks.
Very Low (Acidic) Soil pH Gives Moss and Advantage
Moss loves acidic soil. Grass, however, loves neutral or alkaline soil. To get the most out of your lawn, you want the pH to stay around 6.5 for nearly all grass types. If the pH dips below 5.5, you’re inviting moss to colonize your lawn and it is likely that your grass looks sickly or has developed a spot-type disease.
Poor Air Flow Is Tolerable to Moss But Causes Illness in Turf Grass
To grow tall, straight, and healthy, your grass will need some form of airflow. If your lawn is blocked in on all sides by thick hedgerows and trees, or if you’re tending to a lawn growing between many trees, airflow could be stagnant.
While this is good news on the erosion front, it can make it difficult for grass and grass-like plants to grow. Moss, however, thrives in a low-wind environment. Overseeding without taking care of the airflow problem will lead to a limp, shallow-rooted lawn.
Compacted Soil Is a Problem for Deep-Rooted Grass But Ideal for Moss
Moss has rhizoids, not roots. This makes it perfectly suited to clinging onto your grass blades, the soil, tree bark, and even rock. It doesn’t need to put roots into the soil at all.
Reseeding a compacted lawn with moss overgrowth will likely result in seedlings that fail to thrive and that are quickly grown over and shaded out by the existing moss.
Wet or Poorly Drained Soil Is Ideal for Moss But Rots Grass
As mentioned above, moss doesn’t have roots that reach into the soil. This allows it to avoid most of the soil-based problems grass might have, like root rot. Overseeding a moss-covered lawn before solving drainage issues will result in seeds being swept away, grass seedlings damping off, or newly established patches developing root rot or another water-based disease.
Deep Shade Protects Moss But Chokes Grass Seedlings
Though referenced above, the importance of sunlight to the survival of grass and the elimination of moss cannot be understated. Moss thrives in deep-shade environments and grass can hardly survive in them, no matter which grass type you choose. This makes growing a lawn in deep shade difficult but not impossible.
If deep shade is a challenge you are facing, aggressive pruning can help create enough dappled sunlight to encourage grass growth. In addition, there are several grass cultivars that have been developed for this situation alone. Contact your local grass seed dealer (likely at a local feed or farm store) to see what is available for residential use in your area.
Herbicides and Manual Removal Fail to Eliminate Moss Long term
Removing the moss covering your lawn by hand, by raking, or with an herbicide is unlikely to last in the long term. If you choose to go this route and then scatter seed over the area without resolving each of the challenges mentioned above, the moss will return and it will win out over your chosen grass seeds.
How to Reseed a Moss-Covered Lawn
Reseeding a moss-covered lawn is all about resolving the challenges listed above. Once that’s done, you can seed your lawn as usual. Below are the more specific steps you can take.
First Steps: Course-Correction To Eliminate the Moss Covering Your Lawn
Without doing the fundamental work necessary to eliminate the moss covering your lawn for good, you’ll be wasting your time and money by overseeding your lawn. Below are the five critical challenges you need to overcome to have a moss-free lawn.
- Increase Light Levels – Above all else, your lawn will need adequate light levels. Trim branches, hire an arborist (not a random tree trimming service) to clean things up, and do whatever else you can to improve how much sunlight the area affected by the moss will get.
- Correct pH – Use lime or limestone to bring the pH of your lawn up to ideal or near-ideal levels. This should be done about a month before overseeding your lawn and must be done carefully as it is difficult to bring the pH back down if your lawn becomes too alkaline.
- Loosen Up the Soil (Aerate) – Aeration and limestone can be done at the same time as limestone is most effective when you mix it into the top 4 to 6 inches of soil. Aeration improves the ability your soil will have to hand onto seeds and will make it easy for those seeds to root into the soil once they start to grow.
- Improve Drainage – Drainage is one of the key factors for developing a healthy, lush lawn. How you go about improving drainage will vary depending on your climate and the topography of your yard. Methods could include leveling out the area or planting more low-growing, heavy water-using plants. Underground drainage pipes and channels can also be useful if you live at the bottom of a hill or near a drainage ditch.
- Optimize Air Flow – The least likely to be causing your moss-overgrowth issues is airflow. You can improve airflow in a similar way to improving light levels. Often airflow problems develop when hedges and windrows surround a property, a solid fence has been built, or there is a nearby building shading and “protecting” the property from the wind. Not all of these challenges have a simple or viable solution.
Let the Sun Do Its Work
Once you have done everything listed above, allow some time to pass. Let the sun, wind, and better drainage work to kill off some of the moss for you. This will make taking the following steps that much easier and allow you to see if you even need to overseed at all now that your current grass is no longer fighting against all of these factors that were letting the moss win out.
Choose the Right Grass Type – More Aggressive, Shallow-Rooted, and Shade Tolerant
As noted in the “challenges” section above, the best way to choose a grass type is to do a little research online to find the best broad category or shade-tolerant grass for your area, determine how much light your lawn gets, and then contact a local seed distributor. They should be able to tell you how much light a certain grass cultivar needs and help you decide if it will do well in your location.
Manually Remove As Much Moss as Possible
Now that you have a patch of yard where it should be possible to grow a lawn and the moss is receding, remove as much as you can. This can be done in several different ways. You could remove it by hand, by pressure washing it away, or by raking.
Herbicides can also be used, but the varieties that are highly effective against moss are often not lawn safe and can inhibit the healthy germination rate of the seeds you choose to plant, if nothing else.
Plan The Best Time to Reseed
Now that your yard is prepped and the moss is gone, you need to pick a good time to reseed. In most climates, there are windows for reseeding in the early autumn and all spring. Choosing to reseed a few days before a stretch of rain can also make the process easier.
Fertilize as You Reseed Your Lawn
As you reseed your lawn, apply a slow-release fertilizer to improve nutrient levels and help give the grass seedlings a boost for their first few months of life. Many types of grass seed are sold pre-mixed with fertilizer. If they are not, you can ask the distributor that sold you the seed which fertilizer to use/mix and in what ratio.
Follow The Suggested Next Steps for Raising Healthy Grass Seedlings
Not all grass types require the same amount of care. Once you have reseeded your formerly moss-covered lawn, you should follow the usual steps for germination and helping these new grass seedlings through their first few weeks of life.
Why I Prefer to Remove Moss Before Reseeding
If you don’t remove moss and the conditions that attracted it to your lawn in the first place before reseeding, your effort to reseed and replant is going to waste. While you can get by with leaving the moss and seeding over the top of it if the moss is dying back due to improved drainage and drastically reduced shade, the moss needs to be removed in all other cases. Reseeding after moss removal leads to a much higher survival rate for your new grass.
How Long You Should Wait to Reseed After Moss Removal
If you are reseeding a moss-covered lawn, your first step would be to correct the conditions leading to the overgrowth of moss. Then you remove the moss. Once all of this is done, if climate conditions are right for planting the type of grass you have chosen to plant, you do not need to wait even a single day longer. You can reseed on the same day that you rake up your final layer of moss.
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