Garden Plots

Compost, plants, and tough sites

This is a good time to transplant landscape trees and shrubs. Construction activity rarely leaves soils in good shape. At worst, most of the topsoil may have been removed. At best, there is major soil compaction. What are the best ways to improve degraded soils for your garden and landscape?

The answer, and no surprise for many gardeners, is compost. Compost improves water infiltration, loosens soils, stimulates biological activity, and adds nutrients. But what some interesting research done at OSU’s North Willamette Research and Extension Center in Aurora revealed is that it didn’t really matter whether the compost was tilled into the soil or applied to the surface with new plants installed through the compost.

The amount is important. Two inches of compost applied over 150 square feet was the best amount. That is equal to one cubic foot for that area. After planting, all plots (tilled in compost, tilled without compost, no-till surface compost, and plain without compost or tilling) were mulched with 3 inches of fine Douglas fir bark.

The research group tried both standard landscape plants and some drought tolerant ones. Since the planting area was not watered after the fall planting or the following years, the drought tolerant materials fared much better. Ceanothus gloriosus and Rosemary “Blue Spires” were very strong performers. For more information, see Improving Garden Soils with Organic Matter EC 1561 from OSU Extension publications:

Blackberry control

There is still time to control blackberries. Mowing is an option, but the clumps will return with a vengeance. That said, persistent mowing (8+ times a year), can wear blackberries out. The most common herbicides used to control blackberries are the glyphosate-based products like Roundup™ and triclopyr-mixes like Crossbow™ or Brush-B-Gone. Good leaf coverage is essential. You need at least six hours of dry weather after spraying to ensure absorption.

This time of year, the blackberry leaves might not show any sign of damage but when spring returns, the canes won’t leaf out. You will have a lot of dried up, stickery canes to remove but that should be a pleasure. There may be some weak re-growth. Mow several times and you will eliminate it from the area. Follow all label instructions and restrictions. Don’t spray in the wind.


The Oregon State University Extension office in Columbia County publishes a monthly newsletter on gardening and farming topics, called County Living. It is written and edited by yours truly. All you need to do is ask for it and it will be mailed or emailed to you. Call 503-397-3462 to be put on the list.

Alternatively, you can find it on the web at and click on newsletters. Are you putting up salsa, saving seeds, or thinking about planting grapes? OSU has a large number of its publications available for free download. Just go to and click on publications and start exploring.

Chip Bubl works at the OSU Extension/Columbia County. Call 503 397-3462, or email To reach the Curry County 4-H Extension Services, call 541-247-6672.


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