Robert Hart's seven layers of a forest garden*

Forest gardening is a low-maintenance sustainable plant-based food production and agroforestry system based on woodland ecosystems,  incorporating fruit and nut trees, shrubs, herbs, vines and perennial vegetables which have yields directly useful to humans. Making use of companion plants, these can be intermixed to grow in a succession of layers, to build a woodland habitat.

Forest gardening is a prehistoric method of securing food in tropical areas. In the 1980s, Robert Hart coined the term "forest gardening" after adapting the principles and applying them to temperate climes.

The quickest way to establish a forest garden is to underplant an existing orchard; but even starting from scratch the fruit trees will begin producing relatively quickly.  It's recommended to plant the fruit trees about 20' apart, spacing the other layers between and below them.

1. Canopy, of standard fruit trees such as apples, pears and plums
2. Low tree layer, of fruit and nut trees on dwarfing rootstocks 
3. Shrub layer, of currants and berries
4. Herbaceous layer, of perennial (cut-and-come-again vegetables such as sorrel, wild garlic, seakale and cardoon, comfreys, beets, together with herbs such as mint and lemon balm.
5. Ground cover layer, of creeping plants, such as some Rubus  species and strawberries
6. 'Rhizophere', of root crops  such as winter radishes and Hamburg parsley
7. Vertical layer, of climbers such as runner beans, vines and nasturtiums supported by the trees and shrubs.

* Robert Hart:  http://en.wikipedia.org/wiki/Robert_Hart_(horticulturist)


Robert Adrian de Jauralde Hart (1 April 1913 – 7 March 2000) was the pioneer of forest gardening in temperate zones. He created a model forest garden from a 0.12 acre (500 m²) orchard on his farm.^[1] He credits the inspiration for his work to an article by James Sholto Douglas, which was in turn inspired by the work of Toyohiko Kagawa

And here are some suitable species for each layer:

1   Canopy: choose a range of top fruit and nuts, including different cultivars of the same species that crop at different times and are compatible pollinators.   Such as: apple cultivars, pear cultivars, many plums, damsons and gages, mulberry, walnut and sweet chestnut cultivars.
2   Low tree layer: certain fruits of the canopy grafted onto dwarfing rootstocks, plus hawthorn species, fig, medlar and Siberian pea tree.
3   Shrub layer:  gooseberry, white currant, redcurrant, blackcurrant, jostaberry, Worcesterberry, blackberries, raspberries and their hybrids, quince.

4  Herbaceous layer: vegetables including globe artichoke, chives, tree onions, chard, leek, good King Henry, horseradish, lovage, sorrel, seakale and buckwheat; shade-tolerant herbs such as lemon balm, mint sage and comfrey; and, on the edges, sun-loving herbs including marjoram, thyme, rosemary, lavender and fennel.
5  Ground cover layer: strawberry and similar.
6  Rhizosphere: shade-tolderant root crops such as radish, Hamburg parsley and salsify.
7  Vertical layer: species suitable for growing up trees and shrubs, including runner beans, kiwi fruit, grape vines and nasturtium.

See also: http://regenerativedesigns.wordpress.com/2010/04/18/forest-gardening-vision-pattern-language/