Your questions for this column can be mailed to Round Yard and Garden at 428 W. Liberty St. , Wooster 44691. It is your questions that make this article interesting, so dont hesitate to send them in. Q: I have moss growing in bare spots in my lawn. I heard that lime can kill moss. Is that true? A: No, lime doesn’t kill moss; it just helps plants take in nutrients if (and only if) the soil needs a pH boost. The stronger your grass becomes, the more competition it imparts to moss growth. Moss can be killed with ferrous sulfate or ferrous ammonium sulfate, which you can get at garden supply stores. However, moss will probably come back next year if the lawn isn’t fixed. Moss grows in spots where the grass is thin or missing, so the best way to keep it from coming back is to plant healthy grass there again. First, consider why those spots are bare. Plants that need full sun were put in an area that gets a lot of shade. Does the area not drain well? Is there a lot of thatch or is the soil packed down too much? Fix the area based on its needs and re-seed it with a mix of plants that will do well in your yard. Cover the seedling with a quarter to half inch of clean topsoil. Keep the soil moist until the seedling takes root. It’s important to remember that chemicals that stop crabgrass also stop grass seed from growing, so if you treat the area, wait until next year. Q: How do I control poison ivy in my flower bed?A: “Leaflets three, leave them be. ” Its an old saying, but accurate in describing the poison ivy plant. Each of the three leaflets gets about 2 to 4 inches long, with the middle leaflet being a bit bigger than the other two. The edges of the leaves may be smooth, irregularly toothed, or lobed. Poison ivy is a perennial plant that creeps along the ground and can climb onto trees. There are three options for controlling poison ivy around the yard and garden. First is hand removal. Wear gloves, of course, and be sure to pull the roots out as well. All parts of the plant contain some of the urushiol oil, which is responsible for the skin reactions. To keep from getting poison ivy oils on your clothes and gloves, wash them right away and rinse the washing machine when you’re done. If you want to get rid of a vine that is growing on or around a tree, cutting it close to the ground is your second option. When regrowth occurs, treat the leaflets with an herbicide product containing glyphosate. Because glyphosate is not selective, make sure it doesn’t touch any plants you want to keep. If poison ivy is surrounded by other plants, you can use a brush to apply it directly to the poison ivy. Also, glyphosate or triclopyr can be put on the plants themselves without cutting them down. However, one application will not be enough to get rid of the weed. It will take more than one application, and it works best two weeks before and after the bloom in the early summer. It is never a good idea to burn plants and vines because the smoke and soot from the fire contain poison ivy oil as well. Q: I am finding these black, knotty growths on my plum trees. What’s making them happen, and how can I get rid of them?A: Based on what you said about the tree’s symptoms, you almost answered your own question about what the disease is called. It is called black knot. It is easy for black knot to spread from one plum tree (even a flowering plum) to the next because it is caused by a fungus. Any control effort is going to have to include pruning out the infected stems. When you cut it down, make sure you cut at least 2 to 4 inches (preferably 6 inches) below the knot. The disease can be in the wood below the knot. There is a knot on a big branch that you don’t want to cut out. You can cut it away to good wood and at least 1/2 inch past the knot’s edge. Prunings should then be either burned or bagged and hauled away to prevent spores from re-infesting the tree. Fungicides can also be used to help get rid of black knots, but they will only work if all the knots are cut off the tree or trees nearby. Failure to control black knot will normally result in the death of the tree within a few years.
If your lawn is spotted with patches of green, fuzzy moss, you may be wondering if lime can get rid of it. Moss thrives in acidic soil and lime raises pH, so it seems like a natural solution. But does adding lime really kill off pesky moss invading your grass?
The answer is more complex than you may think. Let’s take a science-based look at the effects of liming on troublesome lawn moss
Why Does Moss Grow in Lawns?
Before looking at lime, we need to understand why moss sprouts in lawns in the first place. A number of factors can create an ideal environment for moss
-
Dense shade – Moss prefers shady spots where grass struggles.
-
Excess moisture – Poor drainage or overwatering leads to dampness moss loves.
-
Compacted soil – Tight, dense soil prevents proper airflow.
-
Low pH – Moss thrives in acidic soil below 6.5 pH.
-
Thin grass – Bare spots and slow growth allows moss to move in.
So moss invades when lawns lack healthy growing conditions for grass. Sunlight, drainage, and open soil favor grass over moss.
Can Lime Really Kill Existing Moss?
Now back to the lime question. Adding limestone raises soil pH, creating less hospitable conditions for moss. But it does not actually kill or remove established moss.
If you already have a moss infestation, lime alone will not solve it. The moss will remain alive and green. Lime takes time to raise pH, so immediate results don’t happen.
In short, lime does not directly kill or remove moss that has already grown in your lawn. It simply makes conditions less favorable for future moss growth over time.
Combining Lime With Other Moss Treatments
To both eradicate existing moss and prevent its return, use lime alongside other moss control options such as:
-
Rake or dethatch to manually remove moss growth.
-
Apply chemical moss killers to poison and dry out moss.
-
Reseed bare patches to thicken up turf.
-
Improve drainage and reduce irrigation to dry out moss.
-
Increase sunlight with pruning or selective thinning of trees.
The lime will gradually raise pH to discourage moss regrowth while these other methods remove the current infestation. This combined approach provides effective, lasting moss elimination.
When to Apply Lime for Moss Control
Liming to control moss should be done at the same times as any other lawn liming:
-
Early spring before grass greenup.
-
Late fall after final mowing.
These times allow the lime to work into the soil before major growth periods for grass.
A soil test helps determine precisely how much lime is needed to reach the ideal pH around 6.5-7.0. Apply no more than 50 lbs. of lime per 1000 sq. ft. at a time.
The Best Lime Products for Moss Prevention
As a soil amendment to discourage moss, the two main types of lime for lawns are:
-
Calcitic lime or calcitic limestone – Made from calcium carbonate.
-
Dolomitic lime or dolomite lime – Contains calcium and magnesium carbonates.
Either can be used depending on soil needs. Dolomitic lime adds magnesium, which some soils lack.
Fine powdered lime works quickest, while pelletized lime provides easier spreading. Use a broadcast spreader for even coverage over the lawn.
Maintaining Moss-Free Grass Long-Term
Once moss has been removed and lime applied, follow best care practices to avoid future issues:
-
Mow high – Keep grass 3-4 inches tall to crowd out weeds and moss.
-
Fertilize properly – Use a complete fertilizer to strengthen grass growth.
-
Minimize shade – Prune encroaching trees and shrubs for more sun.
-
Improve drainage – Aerate compacted soil and fill low spots.
-
Water deeply and infrequently – Allow soil to dry between watering.
With lime to correct the pH balance and proper cultural practices, you can say goodbye to troublesome moss and enjoy lush, healthy grass.
Lime and Moss: Key Takeaways
-
Lime alone does not kill existing moss, only makes conditions less favorable for future growth by raising soil pH.
-
For best results, use lime alongside mechanical removal, chemical treatments, and improved lawn care practices.
-
Apply lime at recommended rates in early spring and late fall for optimal soil incorporation.
-
Lime prevents recurrence of moss only when combined with proper mowing, fertilization, drainage, and sunlight access.
-
Both calcitic and dolomitic lime can raise pH levels and create less hospitable conditions for moss.
By understanding what lime can and can’t do about moss, you can use it effectively as part of an integrated pest management plan. A dense, vigorous lawn is the best defense against invasive moss.
Frequently Asked Questions About Lime and Moss
Still have questions about using lime to control lawn moss? Here are answers to some common queries:
How long does lime take to raise soil pH?
It can take 2-3 months for the full effects of lime to significantly raise pH. This is why early spring and fall are ideal times to apply it.
Can I apply lime at any time of year?
Lime should be applied during active grass growth in spring and fall so the turf can recover from any burn. Summer or winter application risks damage.
How often should I apply lime to deter moss?
One or two times per year is sufficient in most cases. Do a soil test annually to determine if additional lime is needed to maintain ideal pH.
Is pelletized lime or powdered lime better for moss prevention?
Both work equally well. Powdered lime acts more quickly while pellets provide easier spreading. Use your preferred formulation.
Can too much lime cause problems?
Excess lime can raise pH too high and cause nutrient deficiencies. Always follow product rates and do not over-apply. More is not always better.
Should I still reseed and improve cultural practices along with liming?
Yes! Liming alone won’t keep moss away for good. Overseeding, fertilization, aeration, and other best practices are essential.