Finding food-producing plants that are also useful in other ways is a great joy of mine. Many culinary herbs, for example, are not only delicious and nutritious, but they may also attract beneficial insects or deter pests. These four shrubs will not only provide berries for you, but also produce nitrogen to fertilize the garden.
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Why is Nitrogen Important for Plants?
Nitrogen–along with phosphorus and potassium–is a primary nutrient necessary 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 cultivated garden or food-producing area where high productivity is desired, you can use nitrogen-fixing plants as one way to create your own nitrogen fertilizer.
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. Some of it is utilized by the plant itself, but it will also be available to nearby plants as well.
How to Use Nitrogen-Fixing Plants
Plant nitrogen-fixing berry crops in a food forest to feed nearby fruit or nut trees through the soil. Additionally, chop cuttings from the nitrogen-fixing plant to drop around the fruit and nut trees as mulch to feed the soil from above.
Chopping and dropping at the appropriate time of year will help the nitrogen-rich cuttings break down faster.
Composting the cuttings first will create a rich soil amendment for vegetable gardens.
Have your Fertilizer and Eat the Berries, too!
There are quite a number of nitrogen-fixing herbs and trees to add to your landscape, but sometimes a hedgerow of shrubs is just the thing you need for privacy or other uses. Fruit- and nut-producing trees in a food forest will benefit from being paired with any of these multi-purpose, nitrogen-fixing shrubs.
For the following berries to work as edibles, you’ll have to be adventurous enough to try berries that taste nothing like the common berries you’re accustomed to. 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).
Is that enough suspense?
Below are four berry-producing shrubs that might be just the ticket for increasing your garden’s vigor and productivity.
Image via jpc.raleigh on Flickr
1: Buffalo Berry Shepherdia canadensis
Other Common Names: Canada buffaloberry, russet buffaloberry, soapberry
USDA Growing Zone: 2
Fruit Palatability: Fair
Due to buffalo berry’s limited growing range, it will only be useful for a portion of you. However, it 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 Tatters 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. They can also be made into wine.
Goumi is a fast-growing clumping shrub that grows to 6-8′ tall/wide. The shrubs are self-fertile, so only one variety is required. It is naturally found growing in dappled shade in thickets and open woods. Well-drained soil is a must, but it will happily grow in poor soil.
Image via Lotus Johnson 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 considered 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. The tartness mellows after being frozen then cooked.
Sea buckthorn is thicket-forming and will aggressively 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 Josh*m 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 shrub 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 rapidly to slow soil erosion. Careful, these shrubs have thorns!
Read more about silverberry here.
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.
2: Elaeagnus species can be dispersive.
Elaeagnus umbellata is the widely detested autumn olive, also called autumnberry. Native to Asia, it is considered an invasive species in much of North America because of its dispersive habit. The edible berries largely go to waste, falling off the trees and being feasted on by birds, who 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 bring this up to say that planting goumi, another non-native Elaeagnus species, is not a light thing to consider. 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. Rest assured that 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.
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 Lazy Gardener’s Way to Make Fertilizer
- The Cherry Tree Guild and Natural Pest Control
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 shrubs will do the trick.
Are you growing any of these four shrubs? Do you grow your own nitrogen fertilizer?