One of the best ways available for conserving water in your landscape design, and still have a lush green garden, is by using a rain garden. If you haven't ever heard about a rain garden, you need to understand that these are basically a shallow hollow that captures the runoff from rainstorms. These hollows have plants, shrubs, and even trees, which allow the runoff to soak into the ground, instead of preventing it from soaking into the ground. It is fairly easy to build a rain garden, as long as you follow these directions.
- Choose the place, and plants. Before you begin digging, you need to where you plan on having the garden located, as well as the plants that you plan on having in it. Ideally, you will want to place the garden about 10 feet from your house, in an area that receives at least partial sun. Never place a rain garden over a septic tank, or in an area that already has a tendency to collect water, or you can run into problems. Make sure that you pick plants that are indigenous to your area and one that can live well in a "flood plain" style environment. This means plants that have large root structures and do well in both pooling water, and dry periods.
- Map out the area. When you begin mapping out the area, you need to also think about the size and shape of your rain garden. Most rain gardens are between 100 and 300 square feet, though the shape can vary greatly. The easiest types of rain gardens are going to run perpendicular to your rain spout, with a slight down ward slope so that you can catch as much water as possible. you will also want to let the water spread as evenly as possible, so it should be twice as long as it is wide (though it should not be more than 15 feet wide). Use string and gardening stakes to help map out the gardening area.
- Identify your soil. Once you have the area mapped out, you need to get your soil type identified. The reason for this is that you may need to adjust the size of your rain garden, as well as the composition of the soil to help prevent any problems from cropping up. There are typically three types of soil, and they can easily be identified by sight. For example clay soil will have a sticky and clumpy appearance, while sandy soil looks gritty, and the silty stuff looks fairly smooth.
- Begin digging. Following the "map" that you created earlier, begin digging out your garden. Keep in mind that before you start digging, you need to make sure that you don't have any buried cables, pipes, or other impediments. In many municipalities, it is the law to check before you begin digging, so don't get in trouble. As you are digging, you want to know the slope of your lawn. This will tell you the height of the dirt wall, or berm, that you will be creating around the edge of the garden. This wall will be made from the dirt that you are removing from the rest of the garden. for example, if you have a slope of less than four percent, your berm should be no more five inches.
- Start planting. Once you have the garden dug out, and the berm created, you can begin planting the trees. Make sure that when you are planting your chosen plants, shrubs or trees that the ones you use are fully mature rather than seedlings. If you use a seedling, don't be surprised to find that it get's drowned in the first rainstorm.
Once you have finished building your rain garden you will need to keep an eye on it. Rain gardens are meant to "capture" the runoff from a rain storm, but are not meant to become pools of standing, stagnant water. If you find that the water isn't being absorbed into the ground within a few hours then you may need to adjust the soil drainage a bit. Otherwise you are inviting health hazards such as creating a breeding ground for mosquitoes.