QUESTION: I’m looking for the best mulch to use on my tomatoes. What do you recommend gardeners use to mulch their tomatoes? — Jamie L.
ANSWER: Using mulch on your tomatoes is a great way to increase the amount of your harvest and also increase the size and tasty flavor of your tomatoes. There are a few different mulches you can use to get the best results.
In addition to helping you haul in a big harvest and maximizing the size and taste of your tomatoes, mulch also helps the soil retain moisture, choke out weeds, and reduce the likelihood of soilborne diseases. Mulch also keeps the temperature of the soil balanced and, over time, makes soil more nutritious as it breaks down. Let’s take a look at the best mulches you can use on tomato plants.
Cardboard or Shredded Newspaper
Paper products like shredded newspaper and cardboard are an excellent way to choke out weeds in your garden while still letting oxygen and moisture permeate the soil. You can either use heavier mulches on top of paper products to keep them in place or simply dampen your paper mulches to maintain their position. For best results, use a two-inch layer of newspaper (about eight layers minimum), or if you’re using shredded cardboard, a single layer will work. You may choose to top paper mulches with another type of mulch just to keep your garden looking its best.
Grass clippings make a great mulch for tomato plants because of the added boost of nitrogen they’ll add to your soil. Using grass clippings as mulch is also an excellent way to increase moisture in your soil while simultaneously choking out weeds. And if you use grass clippings from mowing your own lawn, you’re saving what you’d pay for a commercial mulch.
A layer of grass clippings about four inches thick around your tomato plants will do the trick. Remember to leave a few inches of room between your grass clipping mulch and your tomato plants to prevent the spread of fungal disease. Grass clippings are especially good at controlling weeds because of the way the blades of grass weave together and form a matted layer of protection.
However, grass clippings add so much nitrogen to the soil when you use them as mulch that you should switch over to another mulch after a while. When your tomato plants have their first clusters of tomatoes on the vine, it’s time to choose another mulch with less nitrogen content. That’s because continuing to mulch with grass clippings will encourage the growth of foliage instead of fruit, and of course you want to encourage the development of the fruits on your tomato plants. For best results, use grass clippings as mulch by adding a fresh layer every other month until the first clusters of fruit are visible on your tomato plants.
Peat moss adds nutrition to your soil as it decomposes, but it has been known to retain moisture to the point of leaching it from the soil. Head off this problem by watering your plants deeply before you spread a peat moss mulch. Peat moss is an especially good mulch for tomato plants because it makes the soil more acidic as it breaks down. It’s also an affordable option. Many gardeners like to use peat moss as a top dressing or mulch because it looks so attractive in the garden.
Using shredded leaves as a mulch for your tomato plants is an especially good way to increase the level of moisture your soil can retain and also keep weeds from claiming territory in your garden. Some gardeners especially like them because, if they use leaves they’ve raked from their own lawns, this mulch can be acquired for free.
However, make sure that you use shredded leaves that have already decomposed and are well rotted. Save the leaves you rake in the autumn, letting them start their decomposition process when they fall from the trees. Your leaves will be well rotted by the time your tomato plants go into the garden.
Make sure to leave a few inches of empty space between your shredded leaf mulch and your tomato plants, as you would with any other mulch. Where mulches are touching the foliage of plants in your garden, they increase the spread of fungal diseases.
Shredded Tree Bark
Some gardeners choose shredded tree bark as a mulch for tomato plants because they like the way it looks in their garden. Visual attractiveness aside, shredded tree bark is also a great way to boost the population of beneficial microorganisms in your soil. A mulch of shredded tree bark will also increase the moisture level of your soil. And shredded tree bark mulch can increase levels of acidity in the soil, which can be a problem with some crops, but is perfect for acid-loving tomato plants. Use a two-inch or three-inch layer of shredded tree bark on top of the soil where your tomato plants are growing, and your garden won’t need you to add mulch for the rest of the season.
Straw is a good option for tomato mulch because of its wide availability and affordability. It’s also a clean mulch that keeps you from getting your hands too dirty when you work with it. Some straw mulches have weed seeds in them that will defeat the purpose of using mulch and allow invasive weeds to infiltrate your garden. Feed hay is a known culprit that contains weed seeds, but golden straw and wheat straw are safer options. Make sure you know what the bales of straw you purchase contain to keep weeds from becoming a problem.
As with all mulches, remember to leave a few inches of empty space between the mulch and the stems or leaves of your plants. If mulch touches your plants’ foliage, it can help fungal disease reach your plants. Keep your layer of straw mulch around four inches thick. A thinner layer isn’t enough to keep weeds at bay, but a thicker layer can increase the risk of fungal disease in your garden.
The mulches profiled in this article are the best options for mulching tomato plants. Remember that you should leave a few inches of empty space between the plants in your garden and whichever mulch material you use. That way you’ll get the benefits of mulching without increasing the likelihood of fungal diseases in your garden.