The Role of Water in a Forest Garden Design

If you are familiar with forest gardens – sustainable food gardens based on a woodlands system – you will know that the initial design stage is important. Overlook something crucial in the design and the forest garden may not develop in the way you had planned. In forest gardening, change is expected – but if we know it is coming we can plan for it as best we can. By thinking carefully about the design before we begin, we can avoid making common mistakes and falling prey to known pitfalls.

I have worked on many forest garden designs for sites all over the world, and have spoken with many clients about the design process. Many gardeners clearly understand issues relating to fertility and nutrient cycles in a forest garden; but one common element is often overlooked: water.

A lack of regard for water, water flow, and water management on a site is a frequent reason why things go wrong.

In this article, I will discuss some of the common water management issues that crop up in forest garden design. I hope that considering these issues might help you begin to think about how water can be managed on your own site and the role water will play in your successful forest garden design.

Soil, Water, and Trees

A lot of forest garden design comes down to considering the intersection between soil, water, and trees. One key goal in a forest garden is working out how to create a stable and largely self-sustaining system. And understanding the soil, water flow and vegetative cover on a site, and how they interact, is crucial.

Water is stored on a site in both the soil and the trees and other plants. How the soil is treated, and which plants are chosen, are two key elements that will determine how much water is stored.

In many situations, you will want more water to be stored in the soil and plants on your property. In certain situations, however, you may wish to reduce waterlogging in the soil in order to grow a wider range of plants in a particular spot. You might want to use trees and vegetation to absorb more moisture from the soil – or to filter water as it is directed elsewhere to where it is more urgently needed.

Riparian Planting Zones

Riparian planting zones (areas beside a river, stream, or other waterway) require particularly careful thought and attention. Forest gardening can aid in developing sustainable riverside planting, which in reducing harmful run off stabilizes banks and keeps water flowing freely and cleanly.

Understanding how water flows across a landscape will make it easier to design forest garden systems that manage water before it gets to riparian zones, and as it passes through them. Understanding the water needs and growth and water-related habits of certain trees and other plants can help in creating systems that work naturally and effectively.

Flood and Flow Management: Slopes in a Forest Garden

Careful consideration is also required when it comes to managing water in forest gardens on slopes. Excess water, flooding, and runoff can damage the soil and make it difficult to establish a forest garden successfully. On sloping sites, the planting itself can aid in improving potential problems. But other interventions may be required in certain cases prior to planting. Earthworks may need to be undertaken.

For example, on more gentle slopes, on-contour swales and berms can be created to slow water flow downhill and keep it around. But these should be considered carefully and may not always be the best option for high rainfall areas or particularly steeply sloping sites.

Terracing may be a better option for optimizing the potential of a forest garden site – especially where there are steeper slopes involved.

In certain circumstances, drainage ditches leading to ponds or reservoirs for water collection may be required or desired.

Water Management in Arid Climate Forest Gardens

In arid areas, too little water rather than excess water is the problem. Water management in low water areas will naturally also involve the use of on-contour swales, basins and other water features designed to keep whatever water is around.

Water management in these systems too can involve earthworks prior to planting. But of course choosing drought tolerant pioneer species, increasing canopy cover, and mulching heavily to improve the soil are key strategies that are also used to manage water effectively over time.

Both in designing and in maintaining a forest garden – water is key. Make sure you think about water and how it interacts with the other elements on your site whenever you are making any decisions. This can be a complex consideration – but it is definitely not one that should be overlooked.