Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu
There is increased grower interest in permaculture systems for fruit and vegetable production. Also called “forest gardening” or “agroforestry”, these systems are based on interplanting perennial tree and shrub crops, with other fruits, vegetables, and herbs below. These systems are common in tropical areas of the world and have been adapted to our temperate areas.
Permaculture systems use fruit and nut trees as the tallest level (apples, pears, cherries, and hazelnuts as examples). The next level is shrubs and cane crops than produce edible products such as blackberry, serviceberry, gooseberry, and currants. Lower levels include permanent sheet composted beds for upright vegetables (peppers, eggplants, tomatoes), leafy crops (lettuce, kale), and root crops (sweet potato). Ground cover edible plants that spread (strawberries, creeping blueberries, creeping thyme) are used for the bottom layer. Additional vining crops (grapes, pole beans, Malabar spinach) then can be added to the mix along with associated plants as a natural trellis. Different levels are interspersed with perimeters often being hedgerows of useful plants (such as brambles).
Brambles such as the primocane blackberries seen in the photo can be used in permaculture systems as second level crops and as borders or hedgerows.
Areas are laid out to allow for mutual benefits (such as wind protection), allow for light penetration (for vegetables below), provide shading in hot summer months (for heat sensitive crops), and allow for access (mulched pathways).
These interplanted systems also will have leguminous plants throughout as a nitrogen source, perennial herbs for aromatic compounds, and plants to promote pollinators. Systems may also incorporate other income generating plants such as edible flowers, woody plants as cut flowers, craft plants, and medicinal plants.
In permaculture systems, plant residues are cut and dropped and leaves that drop from trees and shrubs are left to create natural mulch layers, building a “forest garden floor” rich in organic matter.
Because of the plant diversity, disease and insect pressure is reduced and nutrients are efficiently recycled. These systems are also drought resistant.