Wednesday, May 2, 2012

Garden Mythbusters from Dave's Garden

Two horticultural professionals took some of the most popular garden myths into the university laboratory to prove or disprove the accuracy of these myths. Dr. Linda Chalker-Scott from Washington State University and Dr. Jeff Gillam from the University of Minnesota tested these myths under controlled conditions to determine if they really work.

The Myth
Will placing citrus peel or citrus tea (orange or lime) on an anthill repel or kill the ants or other insects?
Citrus peels are thought to contain a substance that is fatal to insects (d-Limonene).

The Fact

A mixture made from citrus peel was placed on several ant hills. The result was less than overwhelming. The mixture had little or no effect on the ants. A  spray made from citrus peel was applied to a plant that was infested with mites. It did have some effect on the mites but it also damaged the plant. Use caution when applying any citrus material to plants, the citric acid could damage the plant.

The Myth
When planting a new tree or shrub replace the soil in the planting hole with organic material such as compost. Everyone knows that plants love "organic stuff" and will grow rapidly.

The Fact

The roots on newly planted trees or shrubs will indeed grow rapidly in the organic material. The problem is when the new roots reach the edge of the planting hole and the native soil. They will actually turn and circle back into the organic material.
The result in that the organic material will actually hinder further root growth long term.  Moisture is another issue, it will actually wick away from the organic material back into the native soil and thus deprive the roots of the moisture newly planted trees and shrubs need. Use the native soil removed when digging the planting hole to backfill after planting. Your trees and shrubs will do much better.


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