By the time the early season crop is harvested, the canopy of the later season crop will begin to fill in. This is not only efficient but can help with weed management and soil health by keeping living roots in the soil and a plant canopy above the soil surface.
By planting plants with different root structures together, you can aerate the soil and allow plants to pull nutrients from different parts of the soil profile.
- Plants with taproots or tubers like carrots or potatoes can help to break up compaction in the soil.
- Deep-rooted crops like melons and tomatoes pull water and nutrients from deeper in the soil profile.
Adding legumes like peas, beans and clover to your garden is another great way to maximize soil health.
- Legumes fix nitrogen from the atmosphere and reduce your total fertilizer needs.
- Legumes such as snap peas or green beans can be planted as a crop you plan to harvest, or you can sow a legume cover crop underneath your main crop, such as sowing cowpeas under sweet corn in a garden bed.
Some companion plants can physically support each other, reducing the need for staking or trellising. The most famous example of this is the three sisters model, which integrates corn, squash and beans.
- Corn provides a stalk for beans to climb, as well as a visual deterrent for squash insects such as squash vine borer.
- Beans provide nitrogen.
- And squash can be a deterrent to vertebrate animals like raccoons, which often eat sweet corn.
The three sisters model first emerged in Mesoamerica and has been used by many indigenous communities including Pueblo, Mandan and Iroquois tribes for hundreds of years. This model of combining corn, beans, squash and other vegetables is still the foundation of milpa farming systems in Mesoamerica today.