Catch Crops

We’ve all heard of cash crops, those garden plants grown as food, or to sell. But, what can you do with a growing area after a crop is harvested? Catch crops!

Whether you grow your edibles in the ground, raised beds, or containers, there comes a time when the crop matures and the plants are harvested. What’s left? Usually, bare soil and a bunch of stems, cut off at ground level. It’s not attractive, it’s not good for your soil, and it’s bad for the environment.

Post-harvest soil
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After a crop has completed its life cycle, the soil is probably a little depleted. The last thing it needs is exposure to eroding wind, sun, and rain. But that’s exactly what it gets. Without the supporting roots and shading leaves, nitrogen is exposed to the elements, which can cause it to simply blow or wash away. You’ve worked too hard and too long in the garden to lose all that valuable topsoil, so how can you protect it?

Wax beans make a productive catch crop

Plant a catch crop

Catch crops are a combination of cover crops and succession planting. Rather than leaving the soil exposed and the beneficial soil microorganisms to starve, cover crops are used to maintain the relationships between plants, soil, and mycorrhizae that produce nearly all the plants we eat. Catch crops are fast-growing plants that fill in the spaces left behind a harvested crop. In commercial agriculture, catch crops are planted after a field is harvested. In the home garden, you can plant your catch crop before the current crop is even done, providing your soil (and your view) with year round protection.

Sunflowers restore a chicken run

Endive protects a garlic bed

Which plants make good catch crops?

The best catch crops grow very quickly. Radishes, rye, arugula, mustard, lettuce, endive, sunflowers, buckwheat, beans, barley, and oats are generally the best choices for catch crops. Research has shown that these crops help retain nitrogen in the soil, improve soil structure, and prevent erosion when grown as catch crops. Other crops, such as sorghum hybrids, do not make good catch crops. One sorghum-sudangrass hybrid (Sudex) resulted in 50 to 75% mortality of tomato, broccoli, and lettuce crops. This type of chemical warfare is called allelopathy. Stick with the plants listed above. Your soil will be better off, plus you can harvest the beans, sunflower seeds, salad makings, and grain, assuming you do not use your catch crop as a green manure. [If the catch crop is cut and allowed to decompose in place, it becomes a green manure, feeding the soil and improving soil structure even more.]

Benefits of planting a catch crop
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In addition to preventing erosion and keeping your garden attractive, catch crops prevent important minerals [plant food] from being washed away. This reduces ground water contamination. It also improves the size and quality of the crop that follows! Research has shown that crop yields increase by nearly 5%, simply by being grown after a cover crop. Using catch crops and cover crops also increases biodiversity. We are not simply talking about plants and animals here, either. Biodiversity is also occurring at the microscopic level. Soils that contain a wider range of microorganisms and other living things is healthier. Healthier soil grows better food for you and your family. Catch crops also help block sunlight to weeds, competing with them for water and sunlight. This makes it less likely that local weeds will survive long enough to produce seeds that grow into future competition. This reduces the need for herbicides (or the number of hours spent weeding each year).

As your cash crops near the end of their normal lifecycle, be sure to plant catch crops!