My lawn's been getting overgrown with moss for the second season now, especially in the shady spots under the trees. I've tried aeration, but it hasn't done much good. Is there some kind of folk remedy or organic product I could use instead of just poisoning everything with chemicals?
Mechanical removal of moss with a rake or brush is dealing with the symptom, not the cause, so you clear it once and it all starts over again. The key is to change the conditions where moss grows in the first place: it thrives in acidic, compacted, and damp soil in shade.
Try liming your lawn - moss can't tolerate an alkaline environment, and this works even in shady spots. Improve drainage if you have water pooling, and ensure good soil aeration through regular aeration (you might need to do it several times a season, not just once). In deep shade under trees, it makes sense to rethink your plantings altogether - grass often doesn't grow well there anyway, so moss fills the void by default.
I had the same problem under my spruce trees for a long time. I agree that just scraping the moss is useless, but here's the important thing - try sprinkling your lawn with calcined soda or wood ash. Moss loves acidic soil, and these substances make it alkaline, so after a couple of weeks the moss starts to lighten and dies off on its own. After that it's easier to rake it up, and it doesn't come back as aggressively. Plus you'll need to sort out the drainage afterward - moisture tends to pool in shady spots.
Iron sulfate is what actually works without chemicals in the usual sense. It's a micronutrient that acidifies the soil locally and kills moss in a couple of weeks instead of just cutting it down. The ash and baking soda from the previous answers can be used alongside it for a long-term pH shift toward alkalinity, but iron sulfate gives quick results. The main thing after treatment is to improve drainage in shady spots - maybe raise the lawn with wood chips or just add some sand so water doesn't pool.
The main thing is to improve drainage and lighting in shady spots, otherwise no matter what you do, the moss will just come back. Try thinning out the tree canopies so more light reaches the grass, and make sure to loosen the soil deeper - water often builds up under the lawn, which creates perfect conditions for moss. At the same time, you can seed shade-tolerant grass varieties that suppress moss better just through competition for space.
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