Sunday, October 16, 2011

How To Make a Forest Garden, part two


This is the second part of a three part essay on how to get started in forest gardening (read part one by clicking here). For those unfamiliar with the concept, I would suggest reading my Introduction to Forest Gardening.

The Shrub Layer

In part one, we examined the canopy and understory layers of a forest garden. The next layer to consider is the shrub layer. Most shrubs can tolerate shade, and can do well planted beneath larger trees of the canopy and understory layers. Here are some ideas for plants in the shrub layer:

Shrub - Scientific Name - Use

Blackberry - Rubus occidentalis - Fruit
Blueberry - Vaccinium sp. - Fruit
Chokecherry - Prunus virginia - Windbreaks, wildlife habitat, jelly & wine from fruit
Currants - Ribes sp. - Fruit
Elderberry - Sambucas nigra - Fruit
False Indigo - Baptisia australis - Nitrogen fixer
Hazelnuts - Corylus sp. - Nuts
Heath - Erica sp. - Highly attractive to various pollinators
Plum - Prunus sp. - Fruit
Rose - Rosa sp. - Medicinal (rose hips are excellent source of vitamin C), flowers
Silver Buffaloberry - Shepherdia argentea - Jelly from berries, food for wildlife

Some shrubs can also serve as part of the understory layer, such as plums and hazelnuts. In designing your forest garden consider the ultimate size of your other trees as well as the size at maturity of the particular varieties of shrubs you wish to use. There are no hard and fast rules, only general guidelines.

As with trees, you need to consider what varieties will do well in your region, climate and soil type. Also consider your likes and dislikes. The books and online plant databases listed in part one are excellent sources of information to help you decide what plants to include in your forest garden.

Many types of berries can be part of your forest garden shrub layer. Berries are often classified as "superfoods" because they are so nutritionally dense, containing an enormous amount of fiber, vitamins, minerals, bioflavonoids and other nutritional compounds, many of which are thought to protect against cancer and other diseases.

If you are interested in planting hazelnuts and live in the USA, check out the Arbor Day Foundation's
Hazelnut Research Project.

The Herbaceous Layer

The herbaceous layer consists of a variety of perennial vegetables and herbs. Because this layer will be partially to fully shaded, you need to emphasize shade-loving plants. Fortunately, there are many, though you might need to look outside the traditional backyard garden plants. Here is a partial list of potential species to include in your herbaceous layer:

Plant - Scientific Name - Uses

Arugula - Eruca vesicaria - Edible
Chamomile - Chamaemelum nobile - Tea, Flowers
Chives - Allium schoenoprasum - Edible
Comfrey - Symphytum uplandicum - Mulch
Dill - Anethum graveolens - Edible
Garlic - Allium sativum - Edible
Kale - Brassica oleracea - Edible
Lemon Balm - Melissa officinalis - Tea
Lettuce - Latuca sativa - Edible
Mint - Mentha sp. - Tea, Edible, Medicinal
New Zealand Spinach - Tetragonia expansa - Edible
Onion - Allium cepa - Edible, Pest Control
Parsley - Petroselinum crispum - Edible
Rhubarb - Rheum rhabarbarum - Edible
Spinach - Spinacea oleracea - Edible
Stinging Nettle - Urtica dioica - Edible, Mulch

Not only will these plants grow in shade, but many are so nutrition-packed that they make a number of "superfoods" lists. Spinach and kale are among the leafy greens that are on virtually all lists of superfoods. Garlic and onions also make many lists, as does parsley.

Garlic and onions are also known to have mild anti-viral and anti-bacterial effects. As such, consuming garlic and onions may be beneficial to people fighting off colds and other illnesses.

Last year, as an experiment, I planted a bunch of mixed loose-leaf lettuce seeds in an area of my yard that is almost completely shaded by several trees. The lettuce grew quite well, was very productive and lasted a lot longer into the summer than lettuce I planted at the same time but in full sunlight.

Both comfrey and stinging neetle are nutrient accumulators and make great organic fertilizers. They both have extremely deep roots and "mine" many nutrients from the soil, accumulating them in their leaves. The leaves can then be used as a very fertile mulch, added to compost or used in other ways as fertilizers.

Please note that, in the past, comfrey has been used for medicinal purposes, but it also has compounds that can damage the liver in large doses. Do not eat comfrey or use it internally.

The Remaining Layers

It should be noted that the seven layers of a forest garden I am discussing are the layers as described by Robert Hart. Many subsequent writers describe the layers somewhat differently. Some combine the canopy and understory layers, referring to it as simply the tree layer. Others combine the herbaceous, rhizopsphere and ground cover layers into one. And a few talk about fungi (mushrooms) almost as if they were a separate layer entirely.

There are no hard and fast rules or absolute definitions, no right or wrong way to talk about a forest garden, so don't waste much time or energy fretting over such definitions. The important point is that a forest or woodland ecosystem, which we are trying to mimic, is made up of many different layers and we should take advantage of all of them in designing our forest gardens.

The rhizosphere, or underground layer, is the layer made up of root vegetables and tubers. This group is very large and includes traditional varieties such as beets, radishes, turnips, onions, garlic, carrots and sweet potatoes, but also a large number of edible tubers that most Westerners don't typically think of as food. Some examples include lilies (Lilium sp.), daylilies (Hemerocallis sp.), cattails (Typha sp.), arrowroot (Maranta arundinacea), arrowhead (Sagittaria sp.), yacón (Smallanthus sonchifolius), cassava or yucca (Manihot esculenta), pignut (Conopodium majus) and jicama (Pachyrhizus sp.).

Many of the plants of the rhizosphere layer are used as spices, for teas or have medicinal uses. One of these multi-purpose plants is ginger (Zingiber officinale), which as a spice or in a tea adds a favorable zing, and is also thought by some to decrease joint pain, aid against nausea & diarrhea, and is known to contain antibacterial compounds.

Turmeric (Curcuma longa) is another multi-use rhizosphere plant. It can be used as food coloring, a yellowish dye or as a spice. In addition, in many Asian cultures turmeric is traditionally used as anantiseptic for cuts & burns, or taken as a digestive aid. Western medical science has also taken note of turmeric. The U.S. National Institutes of Health has clinical trials underway to study curcumin (the active ingredient in turmeric) as a possible treatment for Alzheimer's, pancreatic cancer, multiple myeloma and colorectal cancer.

The ground cover layer is exactly what it sounds like, that layer of low plants that cover the ground. This layer can be used both to produce food and to control weeds. Ground cover also helps prevent soil erosion and acts as a mulch in helping retain soil moisture. Some plants that make good ground cover include violets (Viola sp.) and nasturtium (Tropaeolum minus), both of which have edible flowers, as well as strawberries (Fragaria sp.).

The vertical layer is made up of vines and climbers. Some possible examples include grapes (Vitisvinifera sp.) and hardy kiwis (Actinidia arguta), which can be grown for their fruit, as well as Scarlet Runner Bean (Phaseolus coccineus) and Wisteria (Wisteria floribunda), both of which are excellent nitrogen-fixers for the soil. Runner beans are edible, but must be thoroughly cooked because some types, including the Scarlet Runner Bean, contain a toxic lectin.

Fungi (mushrooms) are sometimes treated as if they are a separate layer in a forest garden. Many types of mushrooms are edible, some make wonderful dyes, some have medicinal qualities and most make great compost. A few are deadly poisonous, so make sure you know what you are doing. Never eat a mushroom you find in the wild unless you are positive about its identity and safety.

Some mushrooms to consider cultivating include shiitake (Lentinula elodes), kuritake (Hypholoma sublateritum), reishi (Ganoderma sp.) and King Stropharia (Stropharia rugoso-annulata).

How To Make a Forest Garden, part three

Part three will discuss traditional garden vegetables and forest gardening, as well as a number of organizations of interest to forest gardeners. Be sure not to miss part three by signing up for free updates to this website by email, RSS feed reader or by following me on Twitter (see right side column for further informantion).