Permaculture gardens, food forests and orchards often use nitrogen fixing trees and shrubs to supply the nitrogen needed for good production. This video shows 10 of the species we’re working with in the far north of Scotland to feed our food forests, swale systems, garden and orchard without inputs.
Nitrogen-fixing trees play a crucial role in orchards, forest gardens, food forests, and permaculture designs by enriching the soil with nitrogen, which is an essential nutrient for plant growth. These trees are often referred to as “nitrogen-fixing pioneers” because they create favorable conditions for other plants in the ecosystem. Here are some nitrogen-fixing tree species that can be beneficial in these settings:
- Black Locust (Robinia pseudoacacia): Black locust is a fast-growing nitrogen-fixing tree that produces fragrant white flowers in the spring. It’s an excellent choice for improving soil fertility.
- Albizia julibrissin (Silk Tree or Mimosa): This tree has beautiful pink, pom-pom-like flowers and fern-like leaves. It’s a nitrogen-fixing tree that can provide shade and add ornamental value to your garden.
- Honey Locust (Gleditsia triacanthos): Honey locust is another fast-growing nitrogen fixer. It produces sweet, edible pods and can be used for livestock forage in addition to improving soil quality.
- Russian Olive (Elaeagnus angustifolia): Russian olive is a hardy, drought-tolerant nitrogen-fixing tree with silvery leaves. It produces small, edible fruit and is a useful windbreak plant.
- Elaeagnus umbellata (Autumn Olive): This nitrogen-fixing shrub produces small, red berries that are high in antioxidants. It’s a great choice for a hedgerow in a permaculture design.
- Eleagnus multiflora (Goumi Berry): Goumi is a nitrogen-fixing shrub with edible red berries. It’s often used for hedgerows and windbreaks.
- Acacia species: Several Acacia species, like Acacia dealbata and Acacia longifolia, are nitrogen-fixing trees that are well-suited for permaculture systems. They are often chosen for their ability to improve soil quality.
- Caragana arborescens (Siberian Peashrub): This shrub is known for its yellow flowers and edible pea-like pods. It’s an excellent choice for nitrogen fixation and windbreaks.
- Cytisus scoparius (Scotch Broom): Scotch broom is a nitrogen-fixing shrub that produces vibrant yellow flowers. It’s suitable for stabilizing soil on slopes.
- Sesbania sesban (Egyptian Riverhemp): This fast-growing tree can be used in wetland and waterlogged areas to improve soil quality. It produces white to red flowers.
When incorporating nitrogen-fixing trees and shrubs into your orchard, forest garden, food forest, or permaculture design, consider the specific climate, soil conditions, and purpose of each plant. These trees and shrubs not only enrich the soil but can also provide additional benefits such as food, shelter for wildlife, and wind protection. Proper placement and management of nitrogen-fixing plants can enhance the overall sustainability and productivity of your system.
- Scotch broom, Cytisus scoparius
- Siberian pea tree, Caragana arborescens
- Sea buckthorn, Hippophae
- Italian alder, Alnus cordata
- Autumn olive, Elaeagnus umbellata
- Gorse, Ulex
- Ebbings silverberry, Elaeagnus ebbingei
- Honey locust, Gleditsia triacanthos
- Wax myrtle, Myrica cerifica/Myrica pensylvanica
- Black locust, Robinia pseudoacacia
