Adding a rain garden to your edible landscape or food forest can be as simple as planting plants that are suitable for the amount of rain water that sits or comes through certain areas of your landscape.
Boggy or muddy areas in an edible landscape are great places to plant fast-growing, water-loving, food-producing plants, plants that produce a lot of chop and drop material, and plants that spread “aggressively” when given adequate water. Whether you are looking for something food-producing or just would like to dedicate a couple of spots for growing your chop and drop materials to build soil fertility in your food forest, there are a whole host of tips for how to go about designing these rain-collecting areas, also known as rain gardens, to help support the growth of your edible landscape.
Find the areas of your edible landscape where water naturally collects during a heavy rain
These will be the part of your yard, land, or landscape that turn into slush or mud during heavy rains. They might even become shallow ponds or streams during those rainstorms. These are the areas that can be transformed in order to soften the impact of rain, slow it down, and help it absorbed more quickly into the soil..
Choose water-loving plants suited for temporary bog conditions
A lot of these plans include things that grow using bulbs or have large rhizomes. During the growth season, or the warmer months, these could be things like tulips, alliums, banana plants, and a large variety of ornamental grasses. In my own edible landscape, I also have planted a large, clumping bamboo known as Ghost Bamboo or Angel Mist Bamboo, tree collards, taro, strawberries, golden oregano, and hostas.
For a whole list of edible plants suitable for the rain garden, check this out.
Choosing the right size for your rain garden
As with any garden or landscape planting, there’s always the question of just how many plants and what size of a garden bed is enough. When designing a rain garden for those temporary pines that may collect around your house during a heavy rain, the rule of thumb is, bigger is definitely better, but even with a smaller space adding more soil and larger plants can enhance the permeability of your rain garden even if it is not as large.
How to slow the water entering your rain garden
In order to keep as much water on your property so that it does not flood the streets or remove soil from your land with rushing floodwaters, it is important to install ways that help slow the flow of water as it comes down a steep hill or overflows a gutter. However the water enters your property, these methods will help to keep the rain from attempting to wash away your plants before they can get big and strong and keep as much of your soil in your rain garden. These methods will also help to prevent soil and fertilizer runoff from answering the city’s water system therefore reducing the amount of pollutants in the water.
Slowing down rain roof water as it enters your edible landscape
Unfortunately, planting bulbs and rhizome-producing plants may not be enough to get your rain garden well-established and functioning beautifully. For those of you who are attempting to harvest rain water directly from the roofs of your homes, chicken coops, duck houses, sheds, and other sorts of buildings, the sheer force of a heavy rain can wash out your hard won top soil in a single storm. These are great places to plant tall-growing plants with strong trunks or branches that break the heavy stream of rain water to soften it before it can pummel the soft ground, which sweeps away top soil.
Adding gravel or rocks to your rain garden to stabilize the soil
Another very effective method to prevent rain water from washing out your tender, young plants or whisking away your soil is to simply top off your rain garden with gravel or rocks. This also doesn’t have to be a longterm or permanent solution if you’re just waiting for your plants to properly fill in the area so that they can withstand the force of sweeping water since medium-sized rocks can be moved rather easily as the plants fill in.
After doing my own experiments with rocks in the rain garden, I find that adding larger rocks around the border to act as water-breaks before water enters the duck pond, and then having smaller rocks along the inside edge of this rock semi-circle, provides a very attractive hardscaping to the rain garden while allowing the plants inside my little semi-circle to grow freely.
Pea gravel is also a good choice for the inside of this semi-circle setup as the small rocks and sand will provide excellent drainage for your rain garden that will help the water soak into the ground quickly while helping to really add needed stability and structure to the soil and around the roots of your rain garden plants.
Hurricane rains filling up the duck pond by way of the edible landscape rain garden
These are examples of ways to incorporate ponds into your rain garden system. In my edible landscape, I harvest rain water from the roof of the house which is softened by the tall-growing Ghost Bamboo as it comes off the roof. I have horseradish, hosta, a Dark Star Alocasia, asparagus, the Lion’s Head Japanese Maple, the Thai Black banana plant, and sweet potatoes all growing in this rain garden/water harvesting system. All of these plants are water-loving and suited to very moist/bog conditions.