Learn the basics of planting a rain garden

A rain garden is a planted area that collects the run-off water from a roof or paved area and holds it until it percolates down into the groundwater or is evaporated into the air by plants. We'll go over the benefits and how you can plant your own.

• By diverting water away from storm sewers and drainage ditches, more rain is returned to the groundwater and contaminants are filtered out by the soil, rather than being flushed into rivers.
• A rain garden should not have standing water, except immediately following heavy rain. Even after heavy rain, the water should be gone within 48 hours.
• The size of a rain garden is determined by the drainage rate of the soil and the area that will capture the rain. Sandy soils that drain freely are ideal, but most other soils (except heavy clay) are suitable.
• If the drainage rate is slow, it may be necessary to excavate the soil and put a layer of coarse drainage material at the bottom. Test the permeability by digging a small hole, filling it with water, and noting how long it takes to drain.

• Locate the garden in full sun and at least four metres (13 feet) away from the house to prevent any chance of damage to the foundation.
• If the ground is sloping, it may be necessary to build a berm at the downslope side to retain the water. Also make sure that there's no chance of water flooding a neighbour's property following very heavy rain.
• An extension to a downpipe can lead water from the roof to a rain garden, or you can install an underground pipe to take the water to the garden from the downspout.
• If an above-ground extension is used, it should empty onto a pile of stones or a concrete pad to prevent soil erosion.

• Much of the water from a rain garden is evaporated into the air by the plants growing there. These are generally native plants that are able to withstand periodic flooding and also occasional periods of drought during the summer.
• This makes a rain garden a good home for many beneficial insects. However, the range of plants grown is smaller than in a wildflower garden and will often include some woody plants whose deep root system helps to open channels into the subsoil so that water can percolate away.
• Unlike a wildflower garden, the plants in a rain garden are not grown from seed sown on the site, but are nursery-grown young plants. This makes the initial cost greater, but the garden will reach maturity sooner.
• The transplants will need to be kept watered for their first summer, when rain won't be sufficient. In the following years, the plants should be well established  and able to grow without additional water except in prolonged periods of drought.

There are lots of benefits to planting a rain garden, and they can be a lush, beautiful addition to your home. Use this guide to choose the right plants and location for the most vibrant and robust rain garden around.