Nitrogen Fixing Herbaceous Plants for the UK

Most of the nitrogen fixers that are most familiar to gardeners in the UK are found in the herbaceous layer of edible gardens. Traditional edible legumes help to fix nitrogen as part of a crop rotation system for annual beds and are the most well known of all the plants that are involved in this way in the nitrogen cycle.


PeasEdible Peas and Beans (Various)


There are plenty of edible legumes that we are used to seeing in gardens in the UK. Garden peas, broad beans, French or green beans and runner beans are all common examples. Broad beans can be particularly useful as they can be grown in many locations all across the UK and can cope with a little light shade. These crops can be sown the year prior to plants that require a lot of nitrogen and the roots left in place. Alternatively, these legumes can be used as integral parts of annual polycultures or mixed cottage garden style beds.


Lathyrus LatifoliusEverlasting Sweet Pea (Lathyrus Latifolius)


Unlike traditional annual sweet peas, this nitrogen fixing flower is a perennial and is not frost tender. It can do well climbing up amongst, for example, raspberry canes and could be a great addition to mixed edible borders. While this plant does not produce edible pods or seeds, there is some suggestion (though caution is advised) that young seed pods and young shoots can be eaten cooked in stir fries and similar in moderation. In any case, the flowers will attract bees and other beneficial insects.


LupinsLupins (Various)


A range of different lupins can be useful ornamental nitrogen fixers and can also become a useful part of a wildlife garden's ecosystem. These grand, annual flower stalks create beauty and drama in the garden as well as helping nearby plants. They can also self seed each year close to the place where they were originally planted, which can make them a good choice for the sunny edges of low-maintenance woodland gardens.


Wood vetchWood Vetch (Vicia sylvatica)


A number of vetches, which are in the fabaceae (legume) family are useful for providing lower layers in an edible forest garden system. Wood vetch is useful in that is is a woodland plant and so can cope well with the shade cast by trees and shrubs.


White cloverClovers (Various)


Clovers make a useful nitrogen -fixing ground cover for layered edible gardens and can also be useful for use as a green manure to renew nitrogen levels in annual vegetable beds. Both red and white clover can be beneficial when growing under apple trees, while white clover is particularly useful for attracting wildlife.


Of course these are just some of the many useful plants that can help the nitrogen cycle in your garden. For brief lists of some larger nitrogen fixing plants see the articles on nitrogen fixing trees and nitrogen fixing shrubs.


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