Garden Q&A: Moss in veggies raises red flags
Question: I am having a problem with moss in my vegetable garden. Is there anything I can use to eliminate it that is safe for the vegetables?
Answer: Your moss infestation is a symptom of a bigger problem. Getting rid of the moss will only remove the symptom; it will not fix the problem. Yes, there are soap-based moss killers that will kill the moss, but without making other adjustments, the moss will be back.
I suspect you have a pH issue going on with the soil in your vegetable garden. Moss prefers acidic soil conditions (its perfect pH is 5.5), while most vegetables thrive at an optimum soil pH level of 6.5 — still slightly acidic, but far closer to neutral than 5.5.
Test your soil's pH (soil tests can be purchased through the Penn State Extension Service) and follow the test result's recommendations by adding the suggested amount of lime to help raise the pH as close to optimum as possible. Here in Western Pennsylvania, our clay-based soils are naturally acidic, so most soil tests will indicate a need for lime every three to four years. Don't add lime, however, without getting a soil test first. Adding too much (or too little) can exacerbate the problem, leading to a whole different set of issues.
Another possible issue at play is the amount of sunlight your vegetable patch receives. Moss tends to grow in full to partial shade (though it certainly isn't unheard of in full sun locations), while veggies do best with a minimum of six to eight hours of full sun. If the limbs of any large trees overhang your garden, it may be a good idea to hire an arborist to trim the trees to allow more sunlight to reach the garden.
Drainage and soil compaction also may be issues. Moss is very shallow-rooted (they're actually called rhizoids, not roots), and unlike most vegetable plants, moss actually prefers compacted soil that is poorly drained and acidic, so keeping the soil loose and adding plenty of compost or another organic matter to improve drainage will help as well. If the area is low-lying and water tends to collect there, installing a French drain or drainage ditch may be necessary.
Horticulturist Jessica Walliser co-hosts “The Organic Gardeners” at 7 a.m. Sundays on KDKA Radio. She is the author of several gardening books, including “Attracting Beneficial Bugs to Your Garden: A Natural Approach to Pest Control” and “Good Bug, Bad Bug.” Her website is www.jessicawalliser.com.
Send your gardening or landscaping questions to firstname.lastname@example.org or The Good Earth, 503 Martindale St., 3rd Floor, D.L. Clark Building, Pittsburgh, PA 15212.