If you’re getting ready for tomato season and want a simple, natural way to boost your harvest, there’s an old-school gardening trick that’s making a big comeback—burying a fish head underneath your tomato plant. It may sound strange at first, but this method has been used for generations, and there’s real science behind why it works so well.

Fish heads are packed with essential nutrients like nitrogen, phosphorus, and potassium, which are exactly what tomato plants need to grow strong, healthy, and productive. A study from Indonesia’s Environmental Science Master’s Program found that fish heads contain about 8.3% nitrogen, which promotes lush green growth, 4.8% phosphorus for strong roots and flowers, and 1.6% potassium to help produce quality fruit. Beyond that, when fish decomposes in the soil, it becomes a buffet for beneficial microbes, earthworms, and fungi, all of which help break it down and release nutrients directly into the root zone of your plants.

This natural process creates healthier soil over time, improving plant resilience and yield. The idea of using fish as fertilizer isn’t new. Indigenous farmers in North America used to bury small fish under corn as part of the “Three Sisters” planting system alongside beans and squash. While most modern gardeners skip the fish, it was actually a crucial ingredient that powered the entire system. Reviving this tradition with tomato plants gives your garden the same advantage—slow-release nutrients and a thriving soil ecosystem.

Unlike synthetic fertilizers that can be too harsh and fast-acting, fish scraps decompose gradually, nourishing the plant and soil without burning roots or causing nutrient imbalances. Plus, they include trace minerals like calcium and magnesium that further support plant strength and productivity. It’s also a great way to reduce food waste by reusing fish scraps that would otherwise be thrown away. If you’re ready to try it, you don’t need to go on a fishing trip. You can simply collect fish heads and tails over time and freeze them in a plastic bag, or you can ask your local fish market if they have extras. When it’s time to plant, dig a hole at least 18 to 24 inches deep, drop the frozen fish head into the bottom, cover it with soil, and then plant your tomato above it, burying one-third of the stem for stronger root development. Water well and mulch to help retain moisture and keep weeds at bay.

Just remember not to use items like banana peels or eggshells in the same hole—they break down too slowly and are better suited for composting. If you don’t have access to raw fish, you still have options. Canned sardines in water can be used in a pinch, but avoid those packed in oil or seasoning. There are also commercial products like fish emulsion, fish hydrolysate, and fish meal—these are processed to kill harmful pathogens and eliminate odor while preserving the nutrients. Fish emulsion is a liquid made from fish offal, fish hydrolysate is fermented fish in liquid form, and fish meal is a dried, ground mixture of fish parts. All three are widely available and safe to use. For the DIY enthusiast, you can even make your own fish emulsion at home. All you need is fish scraps, sawdust, unsulfured molasses, water, and a five-gallon bucket with a lid. Mix equal parts fish scraps and sawdust, add a cup of molasses, fill the bucket with water to cover everything, and stir it daily for two weeks. Once fermented, strain the liquid and dilute one tablespoon into a gallon of water to feed your plants twice a week. Just be warned—it smells pretty awful. While this gardening hack is highly effective, it’s important to be cautious. Raw fish can carry harmful bacteria like salmonella, and if not buried deep enough, it can attract unwanted visitors like raccoons or stray animals. Some fish may also contain trace amounts of heavy metals, so it’s best to avoid spoiled or questionable fish. As a rule, always bury fish at least 18 inches deep and never use spoiled fish scraps. If you’re concerned about any risks, stick with commercial fish-based fertilizers to stay on the safe side. In the end, burying fish heads in the garden may not be the most conventional or glamorous method, but it’s an age-old solution that works wonders for tomatoes. Whether you go the traditional route with raw fish or use cleaner alternatives like fish emulsion, your plants will benefit from the extra nutrition and your soil will thank you in the long run. So, the next time you’re getting ready to plant tomatoes, don’t just think compost—think fish. Your tastiest crop yet might just depend on it.