Permaculture gardeners look for plants that are multifunctional. Try growing one of these berry bushes that can fix nitrogen in the soil, in addition to providing edible berries!
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Finding food-producing plants that are useful in other ways is a great joy of mine. Multifunctional plants can help improve the efficiency and resiliency of our food-producing landscapes while saving time.
When I learned that there were some berry bushes I could add to my garden that would give nitrogen back to the soil, I wanted to give them a try!
Why is Nitrogen Important for Plants?
Nitrogen is a primary nutrient that is essential for building strong plants with vigorous, healthy growth. Plants need a lot of it. The trouble is, nitrogen isn’t easily or widely available to plants. That’s because it largely exists in the atmosphere, and most plants can’t access it.
In a garden with high productivity, you can create your own nitrogen fertilizer by growing nitrogen-fixing plants, such as the berry bushes in this article.
Nitrogen-fixing plants take nitrogen from the air and convert it into a form that is useable by plant roots in the soil. Certain soil bacteria form nodules on the plants’ roots that “fix” the nitrogen into the soil. The plant uses some of it for itself, but makes the nitrogen available to nearby plants as well.
How to Use Nitrogen-Fixing Plants
Mulching with cuttings of these plants is one way to transfer the nitrogen to your garden beds. (See: Mulching in the Permaculture Garden.) You can also compost the cuttings first to create a rich soil amendment for vegetable gardens.
Permaculture practitioners often plant nitrogen-fixing plants, like these berry bushes, in food forests to feed nearby fruit or nut trees. They will feed the surrounding perennials through the soil. On top of that, the plants can be chopped back regularly. Drop the cuttings around fruit and nut trees as mulch to feed the soil from above.
Tip: Chopping and dropping at the beginning of a rainy season will help the nitrogen-rich cuttings break down faster.
Related: How to Build a Fruit Tree Guild
Berry Bushes for Fertilizer
There are quite a number of nitrogen-fixing herbs and trees to add to your landscape, but sometimes a hedgerow of berry bushes is just the thing you need for privacy or other uses.
The following berries taste nothing like the common berries you’re accustomed to eating from the grocery store. In fact, modern grocery stores are a detriment to having a varied and diverse diet by only making a few fruits available to us.
The modern grocery store phenomenon has reduced our appreciation and wisdom for nutritious wild foods. Where once we had knowledge about local wild plants that could feed us, now we rely on a grocery store to determine what we should eat with shipped-in foods.
If you’re wondering how to make uncommon berries more palatable, see my ideas in How to Grow a Jelly Garden (Jelly being just one idea I mention!).
Would you like to learn more about choosing plants that improve the biodiversity of your garden, reduce maintenance, and increase yield?
You’ll find loads of permaculture information just like this in my book, The Suburban Micro-Farm.
4 Berry Bushes for Increasing Garden Vigor & Productivity
1: Buffalo Berry Shepherdia canadensis
Other Common Names: Canada buffaloberry, russet buffaloberry, soapberry
USDA Growing Zone: 2-7
Fruit Palatability: Fair
This berry bush has a long history of use by native people, and it is an important food source for bears due to its high protein content. Birds and deer are only mildly in favor of this fruit. The flowers are an important source of nectar for pollinators.
The fruit is bitter and is traditionally mixed with other fruits and/or sweetener. Native people made a sauce similar to cranberry sauce. It is eaten raw sparingly because it contains saponins, which can upset the stomach in large amounts. Cooking the berries will mellow the bitterness as well as remove saponin.
What it lacks in palatability this shrub makes up for in nitrogen-rich biomass that will enrich the garden and improve disturbed soil. This multi-stemmed shrub grows to 6-12′ tall/wide and prefers dappled sun in open woods or in sunny thickets at the forest edge.
Read more about buffalo berry here.
Image via jpc.raleigh on Flickr
2: Goumi Elaeagnus multiflora
Other Common names: Cherry silverberry
USDA Growing Zone: 5-8
Fruit Palatability: Good
Goumi is native to Asia and has long been used as a superfood for its high levels of lycopene (more than tomatoes) and vitamins A, C and E. Birds like the berries but the shrubs are resistant to deer. The spring flowers provide nectar for pollinators.
The taste of goumi is astringent but sweet. Though it has a flavor all its own, it has been likened to the tastes of sour cherries, cornelian cherries, and even rhubarb. Waiting until the berries are fully ripe will provide a more enjoyable eating experience.
They can be eaten fresh, but like many tart berries, cooking will mellow the flavor, and they make good sauces, jellies, syrup, and pies. The seeds can be eaten or spit out. Cooking softens them. Or make them into wine!
Goumi is a fast-growing, clumping berry bush that grows to 6-8′ tall/wide. The shrubs are self-fertile, so only one variety is required. You will find this species naturally growing in dappled shade in thickets and open woods. It favors well-drained soil, but it will happily grow in poor soil.
Image via Tatters on Flickr
3: Sea Buckthorn Hippophae rhamnoides
Other Common names: Seaberry, sandthorn, sallowthorn
USDA Growing Zone: 3-7
Fruit Palatability: Good
Sea buckthorn is native to Europe and Asia, naturally growing near the coast in sandy soil or on rocky mountainsides. It is a superfood and traditionally has many medicinal uses as a source for antioxidants, vitamins, minerals, and healthy fatty acids. It provides food and shelter for birds and other wildlife. The berries hang on into the winter and provide winter forage.
The super-tart berries are often juiced and mixed with other fruits for a more enjoyable balance of flavor. The seeds are like apple seeds, but the berries can be run through a food mill to get rid of them. Freeze the berries and then cook them on the stove for about 10 minutes to mellow the tartness.
Sea buckthorn is a thicket-forming berry bush. It will spread through suckers to quickly hold disturbed soil in place and begin healing it through fertilization. The healthier your soil is, the more slow-growing and tame sea buckthorn will be. It likes well-drained soil and is drought tolerant.
Both male and female plants are needed for berry production.
The shrub will grow to 10-20′ tall/wide, and will make a nice privacy screen or security barrier in part shade. It dislikes trimming, and will reduce berry production in a year after pruning.
The shrubs have needle-like thorns that make harvesting a challenge. Be sure to wear rose pruning gloves. Thornless varieties exist, but are not yet widely available in the U.S.
Read more about sea buckthorn here.
Image via Lotus Johnson on Flickr
4: Silverberry Elaeagnus commutata
Other Common names: American silverberry, wolf-willow
USDA Growing Zone: 2-6
Fruit Palatability: Fair
Silverberry is native to western North America and has a long history of use by native people. The bark makes strong baskets and cordage. The shrubs provide good shelter for birds but is not a favorite food source. The flowers are a good source of nectar for pollinators.
The berries are mealy and dry, and can be eaten raw. Native Alaskans fried them in moose fat as a high protein treat. They can also be made into wine.
Silverberry is a multi-stemmed berry bush that will grow 6-12′ tall/wide to form a nice hedge. It prefers sunny edges of open, disturbed areas where its rhizomes can spread to slow soil erosion. Careful, these shrubs have thorns!
Read more about silverberry here.
Image via Josh*m on Flickr
1: Watch out for aggressive spreading from the root zone with sea buckthorn and silverberry.
One way to contain these shrubs is to mow a wide strip on both sides of the row. Keep it mowed to prevent rhizomes and suckers from spreading. In small spaces where preventing their spread is crucial, a rhizome barrier around the border of the planting area would be a wise choice.
Remember that once the soil is healed, or if you already have great soil, these plants will be slow growing and easy to manage.
2: Elaeagnus species can be dispersive.
Elaeagnus umbellata (autumn olive) is widely detested in many regions. Native to Asia, it is considered an invasive species in much of North America because of its dispersive habit. Birds feast on the berries that fall off the trees and largely go to waste. The birds then drop the seeds, which make more trees!
My friend Janet at One Acre Farm has this to say about autumn olive, “…environmentally conscious people realize that using the berries for sauces, fruit leather, and jam requires boiling the berries, killing the seeds…killing the seeds of an invasive shrub reduces its spread…”.
Read more of this article on foraging autumn olives here.
I don’t suggest planting autumn olive, but we can take advantage of its wondrous berries and help slow its spread.
I bring this up to say that goumi is another non-native Elaeagnus species in North America. There are reports that it has already naturalized in 12 states. If you intend to plant goumi, do so with the intention of harvesting as many of the berries as you can.
However, here is my point: Nitrogen fixers—unlike many other invasives—are short-lived. Their job is to jump-start healing in disturbed and damaged soils. Once the soil is healthy enough to support mature trees, nitrogen fixers will begin to die out all on their own without human intervention.
If they’ve spread, it’s because the ecosystem needs their help. Read more about this topic in my article When Weeds are Good. You’ll also find an excellent perspective in the book Beyond the War on Invasive Species: A Permaculture Approach to Ecosystem Restoration.
To read more about nitrogen sources for the garden, see the following posts:
- Transitioning to the No-Till Garden
- 7 Ways to Fertilize the Garden with Comfrey
- The Cherry Tree Guild and Natural Pest Control
The book Edible Forest Gardens, Vol 2: Ecological Design and Practice for Temperate Climate Permaculture was instrumental in my understanding of nitrogen fixation and the plants that perform this function to reduce our reliance on store-bought fertilizers.
If you’re looking to have fertilizer and eat your berries, too, these berry bushes will do the trick.
Need more ideas for building soil in the permaculture garden?
Click here to get your 19-page Guide to Organic Soil Amendments!
Are you growing any of these four berry bushes? Do you grow your own nitrogen fertilizer?