Beneficial weed

A beneficial weed is a plant not generally considered domesticated and often viewed as a weed but which has some companion plant effect, is edible, contributes to soil health, or is otherwise . Beneficial weeds include many wildflowers, as well as other weeds that are commonly removed or poisoned.

Although erroneously assumed to compete with neighboring plants for food and moisture, some "weeds" provide the soil with nutrients, either directly or indirectly.

Many weeds protect nearby plants from insect pests.

Some beneficial weeds repel insects and other pests through their smell [2], for example alliums and wormwood. Some weeds mask a companion plant's scent, or the pheromones of pest insects, as with ground ivy, as well as oregano and other mints.

Some also are unpleasant to small animals and ground insects, because of their spines or other features, keeping them away from an area to be protected.

Some weeds act as trap crops, distracting pests away from valued plants. Insects often search for target plants by smell, and then land at random on anything green in the area of the scent. If they land on an edible "weed", they will stay there instead of going on to the intended victim. Sometimes, they actively prefer the trap crop.

Recent studies on host-plant finding have shown that flying pests are far less successful if their host-plants are surrounded by any other plant or even "decoy-plants" made of green plastic, cardboard, or any other green material.

One scientific study said that simply having clover growing nearby cut the odds of cabbage root flies hitting the right plant from 36% to 7%.

Many plants can grow intercropped in the same space, because they exist on different levels in the same area, providing ground cover or working as a trellis for each other. This healthier style of horticulture is called forest gardening. Larger plants provide a wind break or shelter from noonday sun for more delicate plants.

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