5 Common Mistakes That Are Ruining Your Tomato Crop, According to an Organic Farmer

You can't beat ripe, homegrown tomatoes for their rich, deep flavor. They're one of the most popular backyard crops in the U.S., but they can be tricky to grow. If you're craving more nutritious, delicious tomatoes for your salads, sandwiches, soups and stews, you'll want to avoid some of the most common mistakes that are ruining your tomato crop.

Organic grower and horticulturist Frank Hyman, who's been gardening for 40-plus years, shares advice on raising your best-ever 'mater crop in his third book, Ripe Tomato Revolution: Planting and Growing Every Type of Tomato: Beefsteaks, Cherries, Plums, Dwarfs, and Heirlooms (Cool Springs Press, March 3, 2026). The biggest challenge, he says, is that these veggies (they're actually fruits, but that's what most of us call them) are susceptible to "root rot and leaf maladies."

Mistake Number 1: Overhead Watering

According to Frank, overhead watering is a common mistake that can ruin your tomato crop. "Tomato plants evolved in a low rainfall part of the world: the north coast of Chile with about 20 inches of annual rainfall," he says. "So, they don’t have the immune system to fend off the leaf-killing microbes that are common in high rainfall areas like the Eastern U.S. (which can have) 40 inches of rain, or the Pacific Northwest, which has up to 60 inches of rain." That means you're inviting trouble in the form of disease if the leaves of your tomato plants get wet when you water with a sprinkler or garden hose. Instead, Frank, who is also an award-winning garden designer, recommends using soaker hoses or drip lines. Set a timer so you don't overwater, so you give your plants the right amount and save money on your water bill. You'll also save time, if you're a gardener who tends to stand in the garden for a long time, watering with a hose.

Mistake Number 2: Improper Mulching

"Little or no mulch is a mistake," Frank warns. "Not only will the soil dry out and get compacted, but weeds can spread, because mulch is birth control for weeds. But the worst thing is that raindrops will hit the bare soil and splash microbe-infested soil particles onto the lower leaves, causing early blight and other diseases to spread." Early blight is a fungus that causes small, black or brown spots with concentric rings; it typically starts on lower leaves and moves up the plants. Eventually, the leaves turn yellow, wither and fall off. A layer of organic mulch can help keep the leaves dry, or, he says, "Each time it rains, more microbes will bounce up the 'splash ladder' and kill more leaves."

Mistake Number 3: Fertilizing with Chemicals

Frank says, "Using chemical fertilizer is a mistake. Chemical fertilizers—I call them 'salt fertilizers,' which explains why they burn roots—will infuse your plants with too much nitrogen. The plants may look very green and robust, but that excessive growth is attractive to insects and dilutes the plants’ immune system. A plant on too much nitrogen is a bit like a kid on too much sugar. The kid will grow fast, but not in a good way, and be very active, at least until they crash. Not unlike a too-green plant overwhelmed by bugs and diseases." He uses high-quality organic fertilizers that have a variety of macronutrients and micronutrients to help tomato plants resist diseases and produce more flavorful tomatoes.

Mistake Number 4: Not Using Organic Fertilizer and Compost

"Not using both organic fertilizer and compost is a mistake." They're not the same, Frank explains, but both are important, and they work together. "Compost has very few nutrients for plants. Compost is a bulky food source for good microbes and earthworms. Microbes make nutrients in the soil more biologically available to roots. Earthworms loosen the soil, making room for oxygen, which is an important nutrient for roots that do not get enough attention. Organic fertilizer has nutrients that plants need. These nutrients are not plant food. Only sunlight is plant food. But nutrients for plants are akin to vitamins for people. Vitamins aren’t food for people. We only need tiny quantities of vitamins to stay healthy. And plants only need tiny amounts of nutrients to be healthy. So, use both compost and organic fertilizer."

Mistake Number 5: Pruning Suckers

Frank says, don't prune tomato suckers. "Contrary to conventional wisdom, your plants don’t actually benefit from removing the shoots that come out at a 45-degree angle between the stalk and a side branch." He says agricultural scientists who studied this practice concluded that removing suckers did little or nothing to increase fruit production (remember, tomatoes are technically fruits) or their size. "Instead of pruning suckers, spend that time popping 'Sungold' cherry tomatoes into your mouth while admiring at your garden from the porch."