Gardener’s Notebook by Joshua Burman Thayer
Out in wild areas, nature supports a wide variety of plants living in close relation to each other. Look up in a forest and you’ll see a canopy of tall trees and a sub-canopy of smaller trees. At eye level, there are bushes and shrubs, and if you crouch down, there’s a diverse world of flowers, herbs, and ground cover. Yet another layer hosts fungal growth that lives in fallen dead trees and limbs as well as below ground.
Your cultivated garden spaces can mimic nature with similar layers. This kind of environment is both pleasing to the eye and supportive of wildlife, like the pollinators that nature depends on for fertility. If you design your environment with this diversity in mind, your yard can support a whole forest of edible and fruit-bearing plants that can bring daily delight in nature as well as provender for your kitchen.
As you start your design, keep in mind that each aspect of the day’s sun has different qualities and comes in from different directions. Morning light is gentle, dappled by the deflection of the atmosphere. Midday sun is well known for its strong, bright, and powerful aspect. Afternoon light without cloud cover can be quite searing in California, but in forest-like plantings, it’s softened as it shines through the trees’ upper branches onto lower branches and to other plants below. When we seek to optimize light exposure in a garden, we consider the arrangements of the vertical layers, so in the northern hemisphere, it is strategic to put the tallest trees to the north side of the garden.
Let’s go through these layers from highest to shortest:
Overstory trees are your long-term large specimens. The overstory is a major design element as its species will live for many decades if not a century or more. Nut trees, for instance, can get huge, and like many trees in this category, they do not take well to head cutting to reduce height. For this reason, it is best to situate them on the north side of your food forest. Examples of overstory food-producing trees that do well in the Bay Area include:
Avocado: Plant 10 feet or more away from other overstory trees.
Black walnut: Plant 20 feet or more away from other overstory trees.
Almond: Plant 10 feet or more away from other overstory trees.
PRODUCTION TREES (sub-canopy)
These are your standard 10- to 30-foot-high trees that yield a range of edible products for humans to consume. They can usually be pruned to 10 feet. If part of a food forest tapestry, these can be placed 20 feet apart to let light penetrate the lower layers. By pruning lateral branches and by topping many production trees at 15 feet maximum, you can allow light to reach the lower layers and create a bio-intensive orchard. Examples that do well in the Bay Area include:
Plums: Plant 8 feet or more apart from other trees.
Citrus: Plant 10 feet or more apart from other trees.
Apples: Plant 8 feet or more apart from other trees.
Pluots: Plant 8 feet or more apart from other trees.
Nurseries have begun to sell dwarf and semi-dwarf stocks of larger tree species, and these are a wonderful way to grow food for your family without casting too much future shade. This also makes them an incredible asset to urban design. They can be staggered into the gaps of larger production trees and are easy to harvest at waist to shoulder height. Dwarf trees also fit into the matrix of meadow designs, as they stay human size or smaller and allow light to penetrate all around them. Examples that do well in the Bay Area include:
Apples: Plant 6 feet or more apart.
Oranges: If summers get over 90°F, plant 10 feet apart.
Lemons: Plant 10 feet or more apart.
Pomegranate: Plant 8 feet or more apart.
BUSHES & SHRUBS
Berries invite humans inside the forest to enjoy their sweet fruits, and there is nothing better than a freshly picked highbush blueberry to excite a child and generate a connection to nature’s wonderland. If our goal is to teach enough eco-literacy that our descendants can continue to manage and harvest from these food systems, then it is wise to include berries in your food forest to invite young people into this pleasing interaction with nature.
Currants, blueberries, raspberries, blackberries, thimbleberries, salmonberries, and huckleberries can all do very well in the mixed light and dappled shade of your food forest understory. In the dry and windy topography of California, these crops thrive better with the vertical protection of the food forest. Vines, like grapes, can be grown to climb the trunks of large overstory trees or cover fences.
AROMATIC PLANTS UNDERFOOT
Herbaceous perennials and aromatics help repel rodents, insulate the ground from the desiccating rays of the sun, and provide nectar for pollinators. Many of the herbaceous perennials are easy to propagate from cuttings and continuously grow to fill in the gaps of your evolving food forest. Herbaceous aromatic perennials are great soil builders for orchard soils, where they can be placed at even intervals between the trees.
Take advantage of your food forest floor’s dappled light to produce edible mushrooms. Fungi are essential participants in a healthy forest, where they live in the soil and help break down fallen limbs and trees. In a balanced forest environment, fungi grow naturally, so your food forest will support them as well.
It’s easy to grow shiitake mushrooms on a fallen hardwood log. Hardwood sawdust blocks work best. Low levels of supplementation with oat bran or wheat bran improves fruiting, but some say too much supplementation can cause odd-looking fruits and lower yields. Some strains have also been developed that will grow on straw. You can order shiitake mushroom spawn online and inoculate it into tan-oak logs.
Here are some past Gardener’s Notebook articles to help you with your food forest planning and planting:
Learn about fall planting of food-bearing perennials.
More about the layers in your food forest.
Here’s a fascinating read on the ancient origins of the food forest in human civilization.
Try creating an oyster mushroom patch on straw in a dappled shade portion of your food forest.
Get expert help with your garden from Joshua Burman Thayer at 510.332.2809. Learn more about food forests and permaculture landscape design at nativesungardens.com and from Joshua Burman Thayer’s new book, Food Forests for First Timers.
Joshua Burman Thayer’s Gardener’s Notebook is filled with gardening advice for every season. Visit the whole collection of articles here.