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
We will be working at the food forest on the 1st and 3rd Saturdays of each month from 10am-12pm. The food forest is located at 4700 Irvine St in Hazelwood. It was 4 adjacent vacant lots owned by the URA and now hosts a diversity of edible and otherwise functional tree, bush and groundcover species.
Please come on down, bring a friend and have some fun working in community! Thank you to all of you who have been down this season. Your help is vital to making this a productive and useful space.
There is so much to do and so much that can be done! This week, Saturday June 4th from 10am-12pm, we will be:
Weeding (but of course, gotta keep the knotweed down!)
Mulching- we have a huge pile of wood chips to spread out on the front path
Making sun tea! As long as the sun is shining. We have spearmint on site that is just waiting to become tea.
Pondering the plant landscape and changes that have taken place since last year. Not only the changes that we have instigated but also how the plant community itself has responded to our work.
In other news, the food forest is open to hosting projects. We have some specific areas that we would like to partner with interested people on, including soil and plant testing, soil remediation, understory design work, front entrance design work, and more! Please contact Michelle at firstname.lastname@example.org if you would like to speak further about the opportunities.
Hope to see you at the food forest on Saturday at 10am!