GARDEN FOR APRIL 12, 2008
In the last year we have been seeing many articles on “Rain Gardens”. So what are they? Their primary purpose is to prevent contaminants from reaching our water supply! It is scary when one reads the amounts of cosmetics, medicines, pesticides, and fertilizers that are found in our streams, ponds and lakes. For a number of years now there have been requests for farmers to leave a strip of grass and wild plants along the edge of waterways to catch the fertilizers and “cides” to filter them through the soil instead of draining into the streams. Now studies have found that cities are sending much more contaminants via the gutters and storm sewers than farms do!!! Good builders put their house higher than the street so water will run to the gutter and not down into the basement. But run off from over fertilizing and over watering the lawn are sending these contaminants to the gutter and on to the storm sewer.
We have city rules about pouring anything in the gutter as it goes directly to storm sewers and then on to streams, ponds, and lakes, and does not go into the city water purification system. One article lately asked everyone not to toss out unused prescriptions but to think of the frogs and fish being treated for high blood pressure or hormones they don’t need. The other day I noticed some numbers about city gardeners and lawn owners. By far they use more fertilizers, insecticides, and other pesticides per square foot than farmers, and their runoff is much greater, and it goes directly into the storm sewer by way of the gutters.
A rain garden does not mean a pond. The purpose is to catch and hold the run off before it reaches the gutter. One author says it must never be more than 6 inches deep but wide enough to catch an entire area. Not long ago I visited one put in by Campbell’s Nursery in a front lawn between the house and the sidewalk and planted with plants that can use a little extra water. It is not a bog!!! It needs to be constructed to drain in 48 hours in order to avoid mosquito babies! This doesn’t mean great amounts of soil removed. Some can be used as edging for the low side. If it is heavy clay that holds water tightly something must be done to ensure good drainage. Do not add sand, as sand and clay make cement. Gravel works very well for drainage.
One place that some make into a rain garden is the parkway, which generally catches water from a walk, sloping to the street. As more and more of our country is being covered with cement or asphalt, many heavy rains are contributing to floods as the storm drains can not handle all the run off. By lowering the level of soil just a little and putting in plants tolerant of hot areas, much can be trapped.
Rain gardens are not a dam, but a way water can be held until it drains naturally into the soil. Many years ago in our parkway, we had Hawthorne trees that were drowning in clay holes. My husband Tim dug down on either side of each one until he came to a loose layer. The holes we filled with small stones and rocks. The trees perked up and did fine until the October storm of 1987 smashed them. Not only were the leaves still on but they were solid with red berries that caught and held snow.
You don’t need to get bog plants for your rain garden as there are a number of plants that like their soil moist, and if your rain garden drains in 48 hours, your run off will just give them a big drink.
Another type of green garden, used more in Europe, is the green roof. These are flat or slightly slanted and look somewhat like a raised garden, which will reduce or stop any run off. They need to be placed on roofs that are very strong in order to hold that much weight, be waterproof, with some mechanism to prevent the loss of soil. The plants usually are short and can stand times of extreme dryness. Some of the pictures I have seen are short grasses, wild flowers, sedum, or cactus and are efficient as insulation. They are cool in summer and warmer in winter for the house below.
I just received the book “Rain Gardens” by Dunnett and Clader, both of whom teach at the University of Sheffield, England in the department of Landscape. They tell of many gardens that have been developed in Europe “in which rainfall can be captured from buildings and sealed surfaces to be stored and then released within the landscape”.
Dr Sutton at the University of Nebraska-Lincoln has been working on roof rain gardens for several years. Perhaps we can get him to write of some of the details and how it has been working. In the meantime, don’t waste water, don’t waste fertilizer, and don’t pollute the air and water with over use of pesticides.
BY GLADYS JEURINK
· Book Title by Beard and McKie Workman Publishing:
“Gardening is the Art of Killing Weeds and Bugs to Grow Flowers and Crops for Animals and Birds to Eat”
· Rudyard Kipling said, “Gardens are not made by singing ‘Oh, how beautiful’ and then sitting in the shade”.
· “If a ladybug lands on you, close your eyes and make a wish”. (Old saying, source unknown)
· “A weed is just a plant out of place.” (source unknown)