The seven layers of a food forest

The tallest trees on the lot, and the first thing to decide. In most climates the canopy is about food. In the low desert it is about shade first: a Phoenix yard in July is a different place under a mesquite than it is in the open, and nearly everything below this layer only survives because of it.

Natives do the job best here. Mesquite, palo verde and ironwood grow fast on little water, drop fine litter that becomes mulch, and fix nitrogen in the soil through their roots. A large mulberry or a pecan does the same for shade and adds a harvest, at the cost of more water.

• Shade. Knocks the afternoon sun off everything underneath and cools the house and the soil.
• Nitrogen. Mesquite, palo verde and ironwood are legumes. Their roots feed the soil for every plant nearby.
• Mulch and habitat. Leaf and pod drop builds the soil surface, and the canopy holds the birds and insects the lower layers need.

Woody plants at head height and below. They fill the space between the trunks and the ground, which in a bare desert yard is where the heat and the wind come in. Fruiting shrubs such as blackberries, blueberries in a pot of acid soil, pineapple guava and Barbados cherry give a harvest at an easy height. Native shrubs such as yellow bells, Texas sage and hopseed give flowers, screening and the thickets that birds nest in.

In the low desert a few fruit trees are better grown as shrubs. A pomegranate or a fig left as a multi-stem bush at six to eight feet is easier to protect and picks clean.

• Berries and small fruit. A harvest at arm's reach that starts producing years before the trees do.
• Pollinators. Long bloom seasons for bees, butterflies and hummingbirds, which the fruit trees depend on.
• Shelter. Windbreak, privacy and nesting cover, and a softer edge along walls that otherwise radiate heat.

Living ground cover and the mulch it grows through. In the low desert this is the layer that decides whether the whole thing works. Bare soil here reaches well over a hundred degrees at the surface and sheds water instead of taking it in. Covered soil stays cool, holds moisture between waterings and keeps its biology alive.

Start with wood-chip mulch, four inches deep, over every basin and bed. Then plant low spreaders into it: trailing herbs you can walk on, native daisies that reseed, and a lawn alternative such as Kurapia where you want something to sit on.

• Water. Covered soil loses far less to evaporation, so the same irrigation goes further.
• Soil. Mulch and roots feed the fungi and worms that turn desert dirt into soil.
• Weeds and heat. A closed surface leaves nowhere for bermuda to start and keeps the root zone cool.

Climbers that use somebody else's structure for height. Grapes on a wire trellis along a wall, passion fruit over a seating area, dragon fruit up a post, a native yellow orchid vine along the block fence. A vine produces on almost no ground, which in a small yard is the point, and a vine on a west-facing wall is the fastest shade you can build.

Give each vine the structure first. A mature trunk, a cattle panel arch, a pergola or a fence all work. Keep grapes off the fruit trees until the trees are large enough to carry them.

• Fruit without footprint. Grapes, passion fruit and dragon fruit from a strip of ground a foot wide.
• Shade on walls. A leafy vine cuts the heat a west wall throws back at the yard and the house.
• Flowers. Native vines bloom for months and feed hummingbirds and bees along fences nothing else uses.