The Herbaceous Forest Layer
The herbaceous layer in a food forest is made up of plants, predominantly perennials but also sometimes annuals and biennial plants that have no persistent woody stems above the ground. Within the herbaceous layer, you can find a range of perennial vegetables and herbs, as well as plants that perform specific functions within the ecosystem, such as nitrogen fixation, dynamic accumulation, wildlife attraction, and more.
Herbaceous plants account for a high proportion of the species count in a food forest or forest garden. These species are typically not the headliners – not always attention grabbers like the trees and larger shrubs. But they can become one of the most diverse layers in the system with a wide range of plants fulfilling a wide range of functions and providing a wide range of yields.
The Herbaceous Layer In a Food Forest
When we talk about herbaceous layer in a food forest or forest garden we are talking about the various herbaceous plants that occupy the space in the system below the shrub layer and above lower growing species used as ground cover. (Though groundcover plants are obviously also often herbaceous plants).
Herbaceous plants are plants that do not have a persistent woody framework of branches above the ground. Unlike trees and shrubs they no not form lignin. Most herbaceous plants will die back to the ground at the end of the growing season in temperate climes, though many have roots that will remain alive over the coldest months.
Types of Herbaceous Plant to Consider
When we talk about herbaceous plants, there are a number of different types to consider, and a number of different ways that we might categorise them.
Herbaceous plants can be graminoids (grasses, sedges, rushes and other grass-like plants), forbs (dicot flowering plants), or ferns. The forbs are likely to be the most common category in the understory of food forests or forest gardens.
In a food forest or forest garden, we will typically choose as wide a range of herbaceous plants as possible, to meet our own needs and the needs of the system as a whole. This makes a food forest or forest garden very different to many typical orchards, where grass is sadly typically pretty much all that grows below the trees.
In many food forests or forest gardens, grass growth will actually be restricted. In part this is because we want to promote a much greater biodiversity. But it is also so that we can create a fungal dominant soil found in woodland or forest rather than the bacteria dominant soil found below grassland.
In looking at herbaceous plants to include, we will consider whether the herbaceous plants we are looking at are evergreen or deciduous. Evergreen plants will remain in leaf throughout the year, while deciduous plants will die back (typically in winter in temperate climates). Remember, sometimes, whether a plant remains in active growth year round will depend on location. Plants can be evergreen in one area and die back in another.
Another important thing to consider when looking at herbaceous plants is whether they are annual, biennial or perennial. Annual plants live over a single season, biennials grow one season and flower, set seed and die in the next. Perennial plants will live over three or more years, blooming annually, and can remain in a garden or other planting scheme over a longer period of time.
In a food forest of forest garden, it is typical to choose mostly perennial herbaceous plants, which will require less maintenance and effort from a gardener or farmer over time.
However, biennial and annual plants can also be included in a food forest or forest garden, especially those that self-seed readily in the particular setting where you are growing them. Self-seeding species will pop up each year without the need to resow them yourself.
The Functions of Herbaceous Plants in a Food Forest
As well as looking at whether herbaceous plants are evergreen or not, and the length of their lifecycles, we can also categorize herbaceous plants by thinking about the different functions that they can potentially fulfil.
Herbaceous plants are often used within food forests or forest gardens as:
- Edible species. (With edible shoots, stems, leaves, flowers, seeds and/or roots).
- Species for other useful household yields. (Medicine/ cleaning/ Fibre/ dye/ crafting materials etc...)
- Wildlife attractants (Especially aromatic and flowering herbaceous plants.)
- Species which repel, confuse or distract pest species.
- Species for ecosystem health and fertility. (e.g. dynamic accumulators, nitrogen-fixers...)
Of course, many herbaceous plants can fulfil two or more, even all of these roles. And in food forests or forest gardens, we should always try to select plants (and other elements) that fulfil as many different functions as possible.
To give an example, one wonderfully useful herbaceous plant is the humble stinging nettle (Urtica dioica). This is one that grow wild where I live, but which I allow to grow in my forest garden.
It is an edible species, - the young leaf tips are delicious, especially in spring and the seeds are edible and very healthy too. I also use nettles to make twine for my garden as an excellent natural fibre plant. Nettles also have medicinal properties and I also use them to make a natural hair rinse.
Nettles are also wonderful for native wildlife – attracting a range of insect life. And can both attract predatory insects and serve as a trap crop for certain insect pests. What is more, nettles have also been shown to be dynamic accumulators – I use them to make a liquid feed for leafy plants.
Many other herbaceous plants also have multiple yields and multiple functions within the system as a whole. And, of course, we can select particular species to greatly benefit the main tree species in a forest garden when use in their guilds.
When and Where Herbaceous Plants are Used in a Food Forest
When placing herbaceous plants within a food forest or forest garden scheme, it can be helpful to consider first of all the formation of guilds of beneficial plants around the main productive trees within the system.
Fruit tree guilds can be stand-alone features for a garden, but we can also combine a series of guilds amid other planting as we create a fully fledged food forest or forest garden. Fruit tree guilds will commonly also include shrubs, and climbers, but herbaceous plants are likely to fulfil many of the key roles within each guild.
Guilds (polycultures of beneficial plants) are typically formed within the mature drip line of a fruit or nut tree. The drip line is the line where rain drips from the outermost edge of the canopy.
More shade tolerant species are planted on the shadier side of the tree, and those that prefer a little more light are planted on the sunnier fringe (to the south in the northern hemisphere and to the north in the southern hemisphere).
When creating guilds around fruit or nut trees, one of the most important things to remember is that we need to balance the needs of the different plants carefully, taking into account their root systems, size and growth habit, and nutritional requirements. Making sure that we do not introduce too much competition for a tree with our shrubs and herbaceous plants is key.
As well as being used in the creation of guilds for fruit or nut trees within a food forest or forest garden, herbaceous plants might also be used elsewhere within the system. For example, they might be used in sunny glades within the system (where many herbaceous perennial vegetables and culinary and medicinal herbs will often be best positioned).
Choosing Herbaceous Plants for a Food Forest
We cannot look at herbaceous layer in the systems we create without some consideration not only of the environment, and of the different roles that herbaceous plants can fulfil, but also their place within the system as a whole.
In particular, we need to think about the shade cast by the trees and shrubs in the upper layers of the system, which plants are used as groundcover (which may be herbaceous plants), and especially, perhaps, the rhizosphere and the interactions of roots etc. below the surface of the soil.
When choosing herbaceous plants it can also often be helpful to think about when particular species of flowering herbaceous plant will be in flower. Remember, in a food forest or forest garden we want to welcome in as much wildlife as possible, and have attractant plants in bloom there over as much of the year as possible.
When choosing species to plant we can also consider not only the yields that different herbaceous plants can provide but also when those yields can be harvested (or foraged) from the system. With the right plants you can be harvesting or foraging from a forest garden over much if not all of the year.
By thinking about the benefits that certain herbaceous plants can confer, and the root form, growth habits and requirements of the specific plants we are considering, we can find the appropriate species of herbaceous plant for our particular project and combine these with other herbaceous plants and with other layers of the system in the most effective ways.