Raingarden Guide for Gardeners

(Originally posted on http://blogs.oregonstate.edu/h2onc/2010/01/11/rain_gardens/)

CORVALLIS, Ore. – A new guide on building sunken-bed rain gardens to collect and filter runoff water can help Northwest homeowners learn how to redesign home landscapes to help protect rivers and streams.

Rain gardens can help restore the natural water cycle, according to Rob Emanuel and Derek Godwin of Oregon State University Extension and Oregon Sea Grant Extension.

“As our landscapes became developed, rain falling on hard surfaces was directed to pipes, ditches and storm drains that route to streams or into stormwater sewer systems,” Emanuel said. “The result is too much water arriving in a short amount of time and carrying pollutants.”
Rain gardens work like a native forest, meadow or prairie.

“They capture and redirect stormwater from hard surfaces such as roof tops, driveways, parking lots and streets,” Godwin said. “Rain gardens help keep watersheds healthy by filtering out toxins before they pollute streams and lakes, and they can actually recharge aquifers by encouraging water to soak into the ground.”

The new 44-page illustrated guide, “Oregon Rain Garden Guide: Landscaping for Clean Water and Healthy Streams,” was written by Emanuel, Godwin and Candace Stoughton, who works for the East Multnomah Soil and Water Conservation District. It can be found online at http://seagrant.oregonstate.edu/sgpubs/onlinepubs.htmlor ordered by calling Sea Grant Communications at 541-737-4849. Copies are $4.95 each, plus shipping & handling.
This how-to publication provides information specific to Oregon’s conditions. No stormwater, garden or landscape expertise is necessary to use it. The step-by-step approach teaches how to determine where water flows across a homeowner’s property and the best place to put a rain garden to manage water flow across impervious areas.

The guide points out what local regulations need to be followed and how to determine slope, drainage rates and texture of the soil. Size of the rain garden and volume of water it can hold also are discussed, as are how to excavate, grade and build berms. The guide also recommends native perennials that can withstand both frequent wet and dry cycles.

The guidebook is a joint project of the OSU Extension Service and Oregon Sea Grant, East Multnomah Soil and Water Conservation District, Jackson Soil and Water Conservation District, and the Oregon Environmental Council. Partial funding for the guide was provided by a grant from Oregon Department of Environmental Quality.

Multnomah County Master Gardeners in the News

The Multnomah County Master Gardeners are back in full force, and are doing great things in their community.

Check out the two linked articles, in the sentence above, for more details.

Invasive Species Resources for Master Gardeners

If you haven't had the opportunity to listen to OSU Sea Grant Extension's Rob Emanuel talk about how Master Gardeners can help in the prevent the introduction, establishment and spread of invasive species, you're in luck! Rob has graciously put together a list of resources that Master Gardener volunteers can refer to when working with clients.

His Power Point presentation, 'Invasive Species 101: A Primer for Master Gardeners' is posted online for all.

Here, you can view a list of species which have been classified as noxious weeds in Oregon (i.e. they are invasive). The savvy or long-time gardening may recognize that many of these beautiful plants were once popular among gardeners. These include Bachelor's Button, Spurge Laurel, and Old Man's Beard. Now, instead of being the propagators of invasive plants, gardeners are valued partners in the fight against invasive species.

Why should we be worried about invasive species?

** Invasive species often outcompete native plants and animals, which results in a loss of native biodiversity. If you've ever seen native riparian areas become overtaken by Japanese Knotweed, it is a loss of native beauty and biodiversity to mourn. Or, a drive up to Portland along I-5 provides a glimpse into how English Ivy can overtake forest fragments.

** Invasive species can be costly! For example, leafy spurge is abundant in the Oregon counties of Klamath, Grant and Cook. Where is it present, it can reduce the carrying capacity for cattle by 50-75%! Scotch Broom infestations in Western Oregon are estimated to result in an economic loss of $47 million dollars, due to a reduction or loss of timber production.

Educate yourself about invasive plants, and you are in a prime position to educate clients about the potentially negative impacts of invasive species on our environment and our economy.

When a client comes into the Plant Clinic, or calls the gardening hotline and asks 'What is this plant?' - you have an educational opportunity.

First - inform the client that the plant is designated as a noxious weed by the Oregon Department of Agriculture.

Second - give the client who can't part with the beautiful Butterfly Bush (or another attractive invasive) options for control. Deadhead invasive ornamentals faithfully before they go to seed. Use root barriers to contain an invasive in your yard. Dispose of invasive plant materials (clippings, pulled plants, flowers, ANYTHING) by bagging them in a sealed plastic bag and placing them in the trash. Where municipalities allow, invasive plant materials may be burned.

Third - become familiar with the latest control options for a particular plant. Because Japanese Knotweed is able to grow from even the tiniest of stem fragments - mechanical cutting and removal is not an effective means to control this plant. Leave a small stem fragment (about the size of your thumb) on the ground, and the plant may come back in force. Instead, herbicide applications are much more effective. Of course, whenever using any type of pesticide, including herbicides, follow all label directions and check the PNW Weed book to make sure that a particular herbicide is registered for use by homeowners.

Finally - don't propagate the spread of invasive plants. Don't share a plant with your friends unless you know it is non-invasive. Plant native plants and non-invasive plants in your garden. Check for potential 'hitchhikers' on plants you purchase from a local nursery or at a plant sale. Become educated about the primary invasive plant species in your area - as well as species that are a potential threat to your area, but have yet to be found (hello, garlic mustard!). If you find an invasive plant that is new to your area, report it to the Oregon Invasive Species Hotline.