The Importance Of Nitrogen-Fixing Plants In Your Permaculture Landscape

Posted on: 12 May 2016

Nitrogen is an essential element for plant growth. It is found in abundance in our atmosphere, but the problem is how to get atmospheric nitrogen to your plant roots. Rain is quite good at carrying nitrogen from the air into the ground, but there are also plants whose leaves gather atmospheric nitrogen, carry it to their roots and share it with their plant friends. These nitrogen-fixing plants play a vital role in a permaculture landscape.

Uses for Nitrogen Fixing Plants

Some nitrogen fixers, such as members of the legume family, are also edibles. They have several uses in the permaculture landscape including but not limited to

  • Chop-and-drop - the practice of pruning a plant and dropping the clippings around it or another plant as mulch and green compost.
  • Nurse plant - usually a nitrogen fixing companion plant grown next to or surrounding another edible plant, such as a young fruit tree. The nurse plant helps feed the plant, provides chop-and-drop material and if large enough, protects the young plant from harsh sun or elements.

Choosing Your Nitrogen Fixers

When choosing which nitrogen-fixing plants to use in your permaculture landscape, climate, soil and moisture are all vital considerations for perennials. Annuals, such as runner beans, southern peas and sun hemp, are also commonly used during the summer vegetable growing season. Two of the most popular nitrogen fixers are

  • Pigeon Pea - a fast-growing legume which can grow up to 5 feet tall within four months, pigeon pea is an edible crop in its own right. Grown as an annual in colder climates, it is a short-lived perennial in tropical climates, living up to five years. This plant releases nitrogen from its roots when it is pruned, making it a favorite "chop and drop" plant for green mulching material. It is also often used as a nurse plant for low-growing food crops such as  young berry bushes or lettuces.
  • Black Locust - native to the southeastern U.S., black locust is one of the most popular and useful nitrogen fixers for temperate climates. It is excellent as an overstory tree because its canopy is open enough to let light through to the understory plants. Because it grows quickly, it is popular as a nurse plant for young fruit trees.

Permaculture is growing in popularity as gardeners strive to create food forests on their property. Using nature itself to build soil and grow edible crops is an admirable endeavor that can even be accomplished in an urban yard. Talk to your landscaper (like those at Hickory Lane Farm's Nursery & Landscape LLC or a similar location) about nitrogen fixing plants that will work for your edible garden.