Nitrogen Fixers
Nitrogen Fixers
This collection includes all the plants we carry that are known to fix nitrogen in the soil. Some of these plants are more efficient than others, some produce a crop too, some are native and some are not native.
What is a 'Nitrogen Fixer'?
In short, nitrogen fixers are sort of like plants that fertilize as they grow, which helps reduce/eliminate the need to add nitrogen to your orchard. Nitrogen inputs (eg. urea) are one of the most common fertilizers used in conventional orchards and can have adverse environmental effects.
Nitrogen fixing plants have a special relationship with bacteria that live in nodules on their roots. This bacteria takes nitrogen floating around in the air, and can transform it into a usable form for plants that is held (or 'fixed') in the soil so the plants can then uptake it. This link further explains the process.
Pictured above is a nitrogen fixing nodule on a dormant sea buckthorn plant. In the growing season the nodule will be pink/red in colour when the bacteria living inside is actively fixing nitrogen.
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Species: Elaeagnus umbellata
History: Autumn Olive (aka Japanese Silverberry) is native to parts of Asia and was introduced to the US as an ornamental plant, erosion control, and wildlife habitat in the early 1800s. Its nitrogen-fixing properties and prolific seed production has caused it to become an invasive species in some parts of the US and Canada, so caution is recommended when planting it so it doesn't spread.
Why We Grow It: Despite its bad reputation, this shrub has many beneficial uses. The small red sweet/tart berries are good for fresh eating and making into jams and condiments while the nitrogen-fixing properties of the shrub make it a useful companion plant in orchards and agroforestry systems and for rebuilding the soil.
Species: Robinia pseudoacacia
History: Native to small portion of the United States, the tree first became known to Western science in 1607 when British colonists in Jamestown used it to build houses. It was introduced to Britain in 1636 and has since been used as a landscaping tree in many countries around the world. It is unfortunately considered invasive in many places due to its intense suckering habit and ability to fix nitrogen, allowing it to thrive even in poor soils. However, its hard wood has many uses and the flowers are eaten in numerous European countries and Japan, and it is used medicinally in India.
Why We Grow It: While this tree is considered invasive to southern Ontario as it grows quickly and aggressively, we feel when it is grown with control and awareness, it can be a powerful ally for the following reasons:
- it is a great pioneer species in ecologically disturbed spaces thanks to its resilience and ability to grow and produce nitrogen
- even in poor soil it provides erosion control with its spreading, shallow root system
- it's a fast growing hardwood
- it is preferred for firewood and furniture (60x more rot resistant than cedar)
- bees appreciate it's showy blooms, which are edible and can be enjoyed in salads, jams, cooking and baking, check out Fiddlehead Nursery's locust-flower patty recipe!
- On a farm/tended space, they provide valuable shade for livestock, thicken fencerows, provide habitat for wildlife, increase soil health, and add nitrogen, etc. and are easily managed.
However it is strongly advised not to plant in untended bushland due to its quick and aggressive spread, and resilience once it is established in an area making it quite difficult to remove.
Special Note: We take special care to grade out (remove) any of these seedlings that are showing visible thorns when we dig them in the fall. This increases the likelihood (although we cannot make any guarantees) that you will not have thorns develop on your Hershey Thornless Honey Locust Seedling. If you don't mind thorns on your Honey Locust, the ones we grade out are available here at a lower pricepoint.
Species: Gleditsia triacanthos
History: The mother variety of these seedlings, Hershey, was developed by John Hershey in the early half of the 1900s. After witnessing the destruction of the Dust Bowl, Hershey knew that trees could play an important role in creating more resilient agriculture and sought out nut, persimmon, honey locust, and oak trees in the wild with desirable traits. Hershey was selected for its large pods, thornless nature, and high sugar content (up to 30-40%!). Some of his original grafted trees can still be found in the US today.
Why We Grow It: Our Hershey seedlings will generally be thornless and produce large, sweet pods similar to what made their parent so desirable. However, with natural variation be aware the pods may not be as large and/or sweet as the original Hershey trees and the seedlings may still produce thorns! The pods are great for livestock feed and the sweet pulp can be used in baking, tea, and making beer. The trees themselves are also nitrogen-fixing, popular with pollinators, and have durable, rot-resistant wood.
Species: Gleditsia triacanthos
History: Honey Locust is native to the central United States where it has been used by indigenous peoples as a source of food and medicine. Its name is derived from the pulp inside the pea pods which is quite sweet and crisp. It has been commonly planted as a landscape tree in many places around the world due to its ability to survive many conditions too harsh for other trees. Unfortunately, Honey Locust's tenacious nature has caused it to become invasive in some places.
Why We Grow It: Reaching 30 meters tall, this native nitrogen fixing tree benefits many including bees, wildlife, and even humans: we can use the sweet (honey flavoured) pulp inside their pods in baking, tea or for brewing beer. Honey Locusts grow impressive thorns, 3-10 cm long which can be used for pins or nails in a pinch and the durable, rot-resistant wood has a variety of uses.
Species: Gymnocladus dioicus
History: Kentucky Coffeetrees are native to the southernmost parts of Ontario and the midwestern United States. Despite its fairly large range, it is relatively rare today likely due to evolutionary anachronism. It is believed Kentucky Coffeetrees co-evolved with megafauna that are now extinct, so previously beneficial traits like the thick leathery pod around its seeds now hinder seed dispersal. Indigenous peoples have used the tree as a source of food by roasting the seeds and making a coffee-like drink, and the seeds have also been used as pieces in games and to make jewellery. Nowadays, the tree is planted ornamentally in urban areas.
Why We Grow It: This nitrogen-fixing, Carolinian tree produces seeds that may be roasted and used as a coffee substitute, but be aware the raw seeds are toxic! This tree boasts the largest leaves of any native tree, and it's considered a threatened species.
Species: Hippophae rhamnoides
History: Aside from the fact that Klavdija sea buckthorn originated in Russia, little can be found about the origins of this variety in English.
Why We Grow It: Klavdija, like other Russian-bred sea buckthorns, is noted for its excellent flavour that is on the sweeter side. The bush produces good crops and, unlike other Russian varieties, boasts moderate drought resistance.
Species: Hippohae rhamnoides
History: Lord was developed by Latvian professor of agriculture, Andrejs Bruvelis, and was likely selected for its relatively few thorns and excellent performance as a pollination partner for female plants.
Why We Grow It: A vigorous and strong pollinator, Lord has silvery green leaves which may be used as animal fodder- rather than discarding prunings from the plant, try feeding them to birds, or better yet, let some chickens keep the base of the bush clean and sucker-free by purposefully pasturing them through your plants. Sea Buckthorn have nodules on their roots which help fix nitrogen into the ground, and are a common plant in permaculture orchards for this natural 'fertilizer' effect on plants in their vicinity.
Species: Hippophae rhamnoides
History: Mary sea buckthorn, aka Marija Bruvele, is a Latvian variety that was bred by professor of agriculture Andrejs Bruvelis as a cross between the female varieties Botanicheskaya Ljubitelskaya, Chuyskaya, and native male plants from the coastal area of the Baltic Sea. The goal was to create a variety better adapted to maritime climates. The berries are high in oil content so this variety tends to be grown commercially for oil production.
Why We Grow It: A prolific variety that holds onto berries well, prolonging harvest for 4-6 weeks. The berries have a milder flavour compared to other sea buckthorns with much lower acid content. They can be made into a sunshine yellow juice, best diluted 70% with water for a Canadian version of orange juice. It's also nearly thornless, which makes harvesting much easier.
The leaves and young branches are suitable for animal fodder, which we can attest to from the hens that run around our retail area in summer, sampling from our potted sea buckthorn plants whenever Steph isn't around to chase them away. Sea Buckthorn have nodules on their roots which help fix nitrogen into the ground, and are a common plant in permaculture orchards for this natural 'fertilizer' effect on plants in its vicinity.
Species: Myrica pensylvanica
History: Northern Bayberry can be found from Ontario to Newfoundland and south to North Carolina, most frequently growing along the west coast. Its berries are a food source for several birds and small mammals. The berries also produce a waxy coating that European colonists used to make candles.
Why We Grow It: This hardy, nitrogen-fixing shrub is a great addition to fencelines, native gardens, and areas that need erosion control. The berries are a good food source for several species and the crafty gardener can also use the berries to make clean-burning candles. They will spread over time.
Species: Hippophae rhamnoides
History: Pollmix sea buckthorn was developed as a series of clones to aid in the pollination of female sea buckthorn plants. It is a German cultivar.
Why We Grow It: Although Pollmix does not produce berries, it is a good option for pollinating female varieties! Aside from that, the attractive silvery green leaves can make this shrub an appealing plant to have in the yard, and it is also good for erosion control or creating windbreaks.
Species: Hippophae rhamnoides
History: Sea buckthorn is native to parts of Europe and Asia where it has been a source of food, medicine, and fodder for centuries. These seedlings were grown by us so it will be a bit of a surprise to see what the mature plants are like!
Why We Grow It: If you're looking for a dense, fruiting bush, look no further! These cold-hardy plants are grown from seed, and unlike cultivated varieties it is uncertain whether each seedling is male or female. The nodules on their roots help fix nitrogen into the soil, and the resilient plants are salt tolerant. They can withstand the juglones from walnuts and will reach up to 6 meters tall, forming virtually impermeable thickets if left to their own devices. The berries have a wide range of uses and the leaves can be enjoyed in tea.
Species: Caragana arborescens
History: As the name implies, Siberian pea shrubs are native to Siberia but also parts of China, Mongolia, and Kazakhstan. They came to the US with Eurasian immigrants who used the pods as a source of food while traveling. It has been planted ornamentally and as bonsai, and can be used as erosion control. It is also unfortunately invasive in some parts of the US.
Why We Grow It: A classic permaculture plant! Siberian pea shrubs are nitrogen fixing, very hardy, disease and drought resistant, and, above all, edible. The flowers and young pods can be eaten fresh while the older pods are cooked. The plants are also attractive to pollinators.
Species: Shepherdia argentea
History: Silver Buffaloberries are native to the southern parts of the prairies, parts of the northern US with scattered populations further south. It is an important source of food and habitat for many species including Saskatchewan's provincial bird the sharp-trailed grouse. It is traditionally used by indigenous peoples in its range as food, seasoning, medicine, dyes, and in coming-of-age ceremonies for girls.
Why We Grow It: Silver Buffaloberries are an excellent addition to native gardens, food forests, and hedgerows! They are tolerant of a wide array of conditions and are also nitrogen-fixing. These shrubs are some of the first to produce flowers each spring, making them good resource for pollinators. The berries, which are often red but may be orange or yellow, are a good source of food for birds later in the season. The edible berries are on the bitter/tart side but are much more enjoyable when made into jams, jellies, and pies! Just be mindful these shrubs are thorny and will spread over time.
Species: Alnus incana (likely subsp. rugosa)
History: Native to large portions of the Northern Hemisphere including parts of North America, Europe, and Asia, this widespread tree is often divided into six subspecies. We likely offer Alnus incana subsp. rugosa but with seedlings it is hard to say for sure. Indigenous people have used these trees for medicine and dyes, and they can also be used for erosion control. This subspecies in general is unique for its cold hardiness and ability to fix nitrogen, making it a useful companion plant in permaculture settings.
Why We Grow It: Named for the white lenticels that dot the reddish-gray bark, Speckled Alders can make a useful addition to a permaculture with their ability to fix nitrogen. However, keep an eye on this tree as it tends to spread via suckering (sending up new shoots) and layering (branches rooting into the ground) and can form dense thickets.
Species: Hippophae rhamnoides
History: Tatiana (aka Tatjana) was developed in Latvia by renowned professor of agriculture Andrejs Bruvelis. The large berries, high oil content, and long harvest period have made it a popular commercial variety, particularly in the nutraceutical industry.
Why We Grow It: Tatiana produces large berries with a distinctly dark orange/reddish tinge. They are high in acidity so there is a strong sourness paired with their otherwise pleasant flavour, making them a great option for using in food or beverages. They are also quite high in oil which is said to beneficial for hair and skin.
Special Note: We take special care to grade out (remove) any of these seedlings that are showing visible thorns when we dig them in the fall. This increases the likelihood (although we cannot make any guarantees) that you will not have thorns develop on your Thornless Honey Locust Seedling. If you don't mind thorns on your Honey Locust, the ones we grade out are available here at a lower pricepoint.
Species: Gleditsia triacanthos
History: Thanks to its ability to tolerate a host of adverse conditions that would hinder or kill other trees, Honey Locusts have been cultivated for us as ornamental, urban trees. As a result, several thornless varieties have been developed including the mother tree for these seedlings.
Why We Grow It: Honey Locust has many benefits for permaculture and now growers do not need to worry about popping tires with thorns thanks to these thornless trees - though they are seedling so some may develop thorns though most will not; these can be top grafted with a thornless type if needed. Reaching 30 meters tall, this native nitrogen fixing tree benefits many including bees, wildlife, and even humans: we can use the sweet (honey flavoured) pulp inside their pods in baking, tea or for brewing beer. The durable, rot-resistant wood has a variety of uses.