For those of you into permaculture, you know the importance of nitrogen fixing plants. These plants, especially when pruned release nitrogen into the soil, helping to boost fertility to the plants nearby. By practicing chop and drop when moisture exceeds evaporation, you can supercharge the establishment of a food forest, or a timber forest. These plants can also be great companions in a garden or orchard. Be careful in the garden, as some nitrogen fixers can be invasive.
Alfalfa
Below is a list of nitrogen fixers to consider: (I put a * next to the plants I am personally growing)
|
Plant Type |
Common Name |
Zone Hardiness |
Comments |
|
Full Size Tree |
Black Locust* |
3 |
Large thorns, some say is allelopathic. |
|
Small Tree |
Mimosa* |
6 |
Edible leaves |
|
Small to Med Tree |
Alder* |
3 |
Size depends on variety |
|
Shrub |
False Indigo* |
5 |
I had bad luck establishing this plant |
|
Shrub |
Siberian Pea Shrub |
3 |
|
|
Small Tree |
Redbud* |
5 |
Some debate whether or not it shares the nitrogen it fixes. |
|
Shrub |
Silverberry |
2 |
Eleagnus family |
|
Shrub |
Russian Olive* |
2 |
Said to be invasive, Eleagnus family |
|
Shrub |
Goumi* |
6 |
Good tasting berries, Eleagnus family |
|
Small Tree |
Autumn Olive* |
3 |
Eleagnus family |
|
Med. Tree |
Kentucky Coffee Tree* |
4 |
I have lots of these trees. |
|
Shrub |
Sea Buckthorn* |
3 |
|
|
Med. Tree |
Golden Chain Tree |
5 |
Poisonous flowers |
|
Shrub |
Spanish Broom |
8 |
|
|
Groundcover |
Afalfa* |
5 |
Strong tap root |
|
Groundcover |
Groundnut |
3 |
Edible seed and root |
|
Groundcover |
Lupine* |
5 |
|
|
Groundcover |
Sweet Vetch |
3 |
|
|
Vine |
Wisteria |
6 |
Very fast growing |
|
Large Tree |
Acacia |
7-10 |
|
|
Med. Tree |
Mesquite |
7 |
Can deal with dry climate |
|
Groundcover |
Clover* |
3 |
Good for pathways |
Young Food Forest with Swale
Reference: Toby Hemenway, Gaia’s Garden