{"id":1005,"date":"2026-08-27T13:36:05","date_gmt":"2026-08-27T13:36:05","guid":{"rendered":"https:\/\/www.tomat-pomidor.com\/en\/?p=1005"},"modified":"2026-08-27T15:59:10","modified_gmt":"2026-08-27T15:59:10","slug":"the-great-mulch-mistake","status":"publish","type":"post","link":"https:\/\/www.tomat-pomidor.com\/en\/the-great-mulch-mistake\/","title":{"rendered":"The Great Mulch Mistake: How Fresh Grass Brought Spider Mites to My Tomatoes in Greenhouse"},"content":{"rendered":"
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The Great Mulch Mistake: How Fresh Grass Brought Spider Mites to My Tomatoes<\/h1>\n

\ud83d\udc49 Why You Should Never Mulch with Fresh Grass<\/strong><\/p>\n

\u270d\ufe0f By Pomidoroved<\/strong> | \ud83d\udcc5 Originally published: May 23, 2010 | \ud83d\udcc2 Category: Pests & Diseases, Greenhouse Growing | Photo by: Lana_s_Kavkaza<\/div>\n<\/header>\n
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We all know the benefits of mulching in general, mulching tomatoes in particular, and mulching tomatoes specifically in a greenhouse most of all.<\/p>\n

Wait, you don’t know the benefits of mulching?.. Ugh, what a faux pas! Well then, without getting too bogged down in the details or wandering into the weeds, let me enlighten you.<\/p>\n

What is Mulching and Why Do We Do It?<\/h3>\n

What is mulching? Mulching is when the soil in your garden beds is covered with something. No, not a thick carpet of juicy green weeds. For example, a layer of hay, cardboard sheets, pine needles, or wood bark… Basically, whatever you can get your hands on. People also mulch, with varying degrees of success, using plastic film, wood shavings, sunflower seed husks, compost, and old newspapers… As you can imagine, the list goes on.<\/p>\n

Why do we need this mulching? It’s very simple. First of all, we get rid of weeds. They simply won’t be able to sprout from under a thick layer of old newspapers, dirty socks, and used car tires.<\/p>\n

Second, we eliminate the need for constant watering. The soil under a layer of mulch, socks, and car tires retains moisture much better, which is crucial for both sandy and clay soils. Without mulch, no matter how much you water sand, it dries out instantly, especially in a greenhouse. And clay… clay is even worse\u2014it forms a hard crust and cracks. But under mulch, the sand stays moist, and the clay remains loose and crumbly.<\/p>\n

The third beneficial property of mulch made from natural materials, like hay, is that worms and other beneficial critters breed under it in abundance, loosening the soil and pooping out highly beneficial humus. Plus, the hay itself slowly rots from the bottom, adding fertility to the earth.<\/p>\n

My Fatal Attraction to Fresh Grass<\/h3>\n

Personally, until recently, I was a huge fan of mulching specifically with hay. Or rather, not even hay, but fresh grass clippings. You’d walk into the greenhouse after mulching with it, and the smell was just amazing… And again, the worms, the humus, the pooping… Everything was in perfect working order. So, I didn’t even consider mulching with old newspapers, socks, and car tires as a viable option.<\/p>\n

But then a certain incident<\/em> occurred that forced me to treat old newspapers with a lot more respect.<\/p>\n

The incident\u2019s name was the Two-Spotted Spider Mite (Tetranychus urticae)<\/strong>.<\/p>\n

This microscopic little bugger, practically invisible to the naked eye, had been peacefully spending its time out on the lawn, drinking grass sap and generally not bothering anyone. Since it wasn’t bothering anyone and was invisible anyway, it\u2019s no surprise I paid absolutely no attention to it. I tightly mulched the entire greenhouse with fresh grass clippings and began to enjoy life.<\/p>\n

The same could not be said for the extremely disappointed spider mites. Drinking sap from cut grass that turned into dry hay in a matter of days seemed slightly inconvenient to them. But hunger is no joke, even if you are a microscopic little bugger of a spider mite. So, driven by starvation, the mites began to migrate onto the tomatoes.<\/p>\n

The Invisible Invasion<\/h3>\n

At first, wilted leaves appeared on the lower tiers of a couple of bushes in different parts of the greenhouse. Blaming it on yet another unknown fungal plague, we just picked off the wilted leaves. Since we really don’t like using chemical pesticides or miticides, we didn’t spray anything. Besides, there were no obvious symptoms other than the wilting leaves. Overall, we harvested tomatoes with varying success until autumn, continuing to just pull off the wilted leaves. The harvest wasn’t great that year, but then again, the weather was quite cold, too.<\/p>\n

I must say, this strange “disease” didn’t upset us too much at the time.<\/p>\n

Then, sometime in early September, when most of the harvest had already been picked, we simply didn’t visit the garden plot for a couple of weeks. The weather turned out to be sunny, hot, and dry, and the greenhouse doors had been shut…<\/p>\n

In those two weeks, a Sahara desert formed inside the greenhouse. But not a desert of sand\u2014a desert of cobwebs. The tomatoes, the remaining weeds, and absolutely every piece of vegetation were entirely smothered in thick webbing. An attack of mutant spiders? No, not spiders. And not mutants. The hot, dry weather had simply fully activated the spider mites that had crawled out of the fresh grass clippings back at the beginning of the summer.<\/p>\n

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The Moral of the Story<\/h4>\n

So here is the conclusion: before you mulch your tomatoes with grass clippings, let the grass dry out thoroughly in the sun first<\/strong>, so the spider mites can crawl away to mind their own business. Or… maybe give those old newspapers a second thought.<\/p>\n<\/div>\n<\/div>\n

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\ud83d\udcd6 Read More Greenhouse & Gardening Stories:<\/h4>\n