Nitrogen fixing shrubs are valuable in agroforestry systems. They can be integrated into perennial agriculture systems to restore and maintain nutrient cycling and fertility self-reliance. The following 3 nitrogen fixing plants have additional uses and benefits as well. This is a quick snap shot of nitrogen fixing plants. Please share your experiences with these or other plants used primarily to fix nitrogen.
1) Siberian Pea Shrub (Caragana arborescens)
• Ornamental, edible, and can be used in windbreaks
• Does best in full sun
• Tolerant of adverse growing conditions, such as poor, dry soils, extreme cold, salt, and wind
• Can become invasive
2) Ceanothus (Ceanothus americanus)
• Also known as New Jersey Tea
• Non-leguminous nitrogen-fixing shrub native to most of Eastern North America
• Often found in dry woods and gravely banks
• Can grow 2-4 feet tall
• Prefers sandy or loamy soils.
• Does best in well-drained soil but can grow in poor soil.
• Can grow in sun or semi-shade.
• Does not take well to root disturbance or heavy pruning.
• Attracts butterflies, hummingbirds, and birds.
• In addition to fixing nitrogen, Ceanothus has numerous medicinal qualities. It has been used to treat fevers, sore throats, bronchial disorders, lymphatic congestion, and sores.
3) Alder (Alnus spp.)
• Native, non-leguminous nitrogen fixing tree
• There are several species native to Pennsylvania, including A. incarnata, A. serrulata, and A. viridis.
• A. viridis is an endangered species in Pennsylvania.
• Most alders grow 15 to 25 feet tall
• Tolerates a wide range of soils, including heavy clay or poor soils.
• Tolerant of polluted soils and can be used for land reclamation.
• Grows quickly when young, and regrows when coppiced.
• Twigs and branches or coppiced pieces of alder are often used for basketry.
• It is not very durable or very good firewood.
• It does not start to cast shade until late May.
• Has a heavy leaf canopy and can help to build up humus in the soil.
Compiled by Elizabeth Lynch, Troy Hottle, and Juliette Jones
Pc Communities, on-line or other
Pittsburgh Permaculture’s Resources
- What is Permaculture? – A brief description of permaculture
- Pittsburgh Hardiness Zones – this article takes a detailed look at the USDA hardiness zones and the updated Arbor Day Foundation map
- Patterns and Design – a discussion about the pervasive patterns of nature and how they might be integrated in our designs
- Fruit Tree Guild - this page describes a permaculture design we installed at the Edgerton Avenue site in Point Breeze
- Permaculture Pond – a description of a pond install that is designed to function without pumps or filters while providing a beautiful, productive habitat
- Grape Vine Awning – a page explaining the placement of a grapevine on the south side of the home to help reduce energy costs
- Vegetable Seed Starting – color coded charts to help you time your vegetable starts
- Actively Aerated Compost Tea – a guide to making your own compost tea and constructing a cheap yet effective brewer
- Grafting at Home – an article explaining the theory of grafting fruit trees and how to do it with what you already have at home
- Stackable Worm Bin How-to – a picture guide to making your own stackable worm composting bin using 5 gallon buckets
- Addressing Concerns about Worms – a discussion about the recent concerns surrounding invasive worms and the relative risk they pose
National/ International Resources
Permaculture Design Sale!
Now through October 1st…
Have your landscape designed at a discounted rate. We design landscapes of all sizes and conditions and would love to work with you to bring your dream to reality. Permaculture design utilizes ecological principles to create landscapes based on your wants and needs and in accordance with nature.
One of the principles that we follow is to make the landscape as self-sustaining as possible, which means less labor year after year to maintain.
From now through October 1st, we are offering a 20% discount off of our design services! Let’s talk…
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Fall is the perfect time to design your space so that come spring, you are ready to plant!
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Peace & enjoy the last days of summer :)