Drainage & Downspouts
Whenever practical, direct roof drains to lawns and gardens instead of concrete driveways or sidewalks. There are two benefits to directing roof drains to lawns and gardens. One benefit is water conservation, since some of the runoff soaks into the lawn and garden instead of flowing to the street. Another benefit is reducing or eliminating pollution in urban runoff. When roof runoff soaks into the ground, materials (sediments, nitrogen, etc.) are trapped in the soil instead of ending up in a lake or river.
Plants in your landscape must have both air and water around their roots. Good soil drainage provides both in the root zone. Poor drainage typically results in excess water (waterlogged) and little air around the roots. This causes the plant to suffocate, wilt and die over time.
Carefully evaluate the drainage of the area to be planted. If a site does not drain, it will not support healthy plants. Poorly drained soil is responsible for more plant failure than any other single cause. One way to check the percolation of the soil is to dig a hole approximately 2 feet deep and fill it with water. Let the water drain away and then refill the hole. If the water drains away twice within an hour, the soil is well drained and will support most any plant that insists on impeccable drainage. (e.g., Calylophus). If the water drains within 6 hours, it is suitable for plants that will accept heavy soil (e.g. Canna, Flame Acanthus). If water stands beyond six hours-consider building a raised bed or install a subsurface French drainage system (perforated pvc pipe in a gravel bed), or planting plants that tolerate poor drainage.
Signs that you may have poor drainage:
- Approximately 4 - 5 hours after a heavy rain, you still see standing water in the planting area.
- If the planting area is at the bottom of a slope.
- If you have predominately clay soils.
- If you have shallow soil over a hardpan or limestone subsoil.
- Amend existing soil by adding organic matter (3" - 4" over the surface). Commercial or homemade compost is a good source.
- Raise the beds and fill with amended soil.
- In very bad situations, an underground drainage system may need to be installed. Either contact a landscaper, nursery, or home supply center/hardware store for additional information.
- Plant plants that tolerate poor drainage.
You can also have too much of a good thing when your soil drainage is too fast, as happens in very sandy soils or where the terrain has too steep a slope. Water is either not retained or it is carried off before it soaks into the ground.
Collecting and using Rainwater
Downspouts can easily be diverted into a rain barrell to store rainwater. A rain barrel collects and stores stormwater runoff from rooftops that would otherwise be lost to runoff and diverted to storm drains and streams. By capturing and temporarily holding water, rain barrels help add capacity to the city’s sewer system and reduce sewer overflows to creeks, rivers, lakes, and other water sources. The collected rain water can be used for irrigation to water lawns, gardens, flower beds, and trees, or even car or window washing. Rain barrels can be purchased at some local home improvement stores, on-line, or they can be easily and cheaply built with readily available materials. Best of all, once it is set up you have a free supply of water for your garden!
Using rainwater has numerous benefits over using city water, or tap water. Rain water is considered "soft water," meaning it contains no chlorine, lime, or calcium, (often found in tap water) which can be detrimental to plants over time.
[more information on rain barrels coming soon]