by: Elizabeth Ussher Groff In a “Healthy Soils” talk at Metro’s Demonstration Garden in the Brentwood-Darlington neighborhood, renowned gardener Glen Andresen discussed soil testing, cover crops, and compost.

A blue canopy tent sheltered twenty-one people from the late morning sun in Metro's Natural Techniques Garden at 6800 S.E. 57th, south of Duke Street.

The occasion was an August 27th Metro workshop, 'Healthy Soil for Healthy Plants'.

Workshop presenter Glen Andresen teaches frequent Metro classes, and is widely recognized as very knowledgeable and down to earth (as you would expect!) about gardening.

He began by pointing out that the 57th Avenue Demonstration Garden had started in the late 1990's on a piece of land about the size of a standard house footprint - 50 by 116 feet. Today it is filled with examples of native plants (labeled) that attract bees, butterflies, and beneficial insects, and it features easy-to-construct water conservation techniques.

'Metro's natural gardening program is designed to lessen the use of pesticides, which are some of the most expensive and toxic wastes to dispose of,' Andersen explained. Related to disposal cost, he commented that as of August 1st Metro had reinstated a $5 fee for dropping off hazardous waste or pesticides at either of the two Metro disposal depot sites.

However, residents can call the Metro recycling hotline 503/234-3000 for the dates of free hazardous waste collections in neighborhoods during the year. He added that the best choice for water quality and health reasons would be to avoid purchase and use of toxic chemical pesticides when possible.

Andresen asked participants why they had come to this particular ninety-minute workshop. Some of the topics of interest expressed by the attendees were soil testing, cover crops, and compost.

Addressing the issues in order, interwoven with characteristic humor and gardening anecdotes, he began with soil testing - not a high priority for his own gardening, he said.

'I think [concern about] the pH of soil is overblown in importance. Most Willamette Valley soils are in the 5 range, but compost can buffer the pH needs of a plant.' He added that he has not found soil self-test kits to be very effective, and mentioned that OSU Extension Master Gardeners often have free soil pH testing on-site at their events, for those who wish it done.

As for cover crops, Andresen's own favorites are fava beans and crimson clover. He advocates cutting down the crops in early spring and leaving the rest of the root material to decompose underground. This practice adds nutrients to the soil and allows the soil to remain relatively undisturbed. Planting in and around the decomposing material is not always the most aesthetic result, but he said that it works well for him.

Compost, Andresen contended, is the key to good gardening. 'Compost is to plants as aspirin is to humans. Whatever ails, add compost.'

Explaining the science of compost - microorganisms such as bacteria and fungus digest material added to a compost pile - he offered a helpful analogy: 'Think of the organisms in your soil as the 'stomach' of your plants. The bacteria and fungus secrete enzymes and acids that help release the nutrients.'

Such microorganisms need the right balance of carbon and nitrogen, in addition to water and air. Examples of carbon materials would include dried leaves (not laurel or rhododendron, unless shredded) and dried grass. He suggested that dried leaves also be used to help keep the fruit fly population down.

Andresen observed that he is a firm believer in the value of leaves left to decompose under proper conditions. Long term, he says most leaves left outside for three or four years can contain more nutrients (except for nitrogen) than manure.

Examples of nitrogen materials would be green lawn clippings, produce scraps, manure, and coffee grounds. Other examples of carbon materials are leaves, straw, wood chips, and dried grass. Getting the right ratio of carbon to nitrogen is important in creating quality compost, he added: 'The rule of thumb is two to one - twice as much carbon material as nitrogen.'

Concluding the subject, Andresen offered this rule for compost: 'Don't give your compost pile too much of one thing. You don't want to give it indigestion.'

To learn more about such classes as well as free printed Metro resources, go online to: - and click on 'Natural Gardening'. Or, call Metro at 503/234-3000.

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