Let Hardy Shrubs Be
Most grow well without fertilizer or pruning
Many home gardeners fertilize their shrubs regardless of whether the plants need it. I have lived in my current home for 15 years, and have not yet applied fertilizer to my Japanese hollies, yews, crape myrtle, forsythia, photinia, mountain laurel, heavenly bamboo or viburnums.
The more you fertilize shrubs, the more new growth they will produce and the more often you’ll have to prune. Unless the plants appear to be deficient and not growing well, leave them alone except for pruning for proportion. This holds true especially if the plants are part of your foundation plantings. Foundation plantings often become over-crowded and unmanageable when fertilized.
Pruning and shearing is a dwarfing process that results in reducing the nutrient needs of plants initially. Both pruning and shearing, however, stimulate plants into producing more branches.
The difference between pruning and shearing is the number of branches being cut and the number of new branches produced. When you selectively prune, you remove larger branches originating more in the center of the plant, resulting in fewer new branches.
If you shear a plant instead of pruning, you create even more problems by cutting more young branches and the plant grows many more new branches.
Likewise, if you fertilize the plants that you prune, you force the new branches to produce more growth, starting a vicious circle.
If the shrubs are not performing as well as you think they should, first have the soil tested and examine drainage conditions. Poor drainage often creates a greater problem for growing plants than poor nutrition or soil pH. If you see water standing for long periods of time or if the area remains wet and spongy for a week or more following a heavy rain, the soil is most likely too wet for efficient plant growth.
Drainage problems can be solved in a number of ways: First, on a hill, you can install underground drainage if there is an area to drain the water into. Second, if the land is flat, you may need to install raised beds. Third, select plant species that can tolerate growing in wet soils in the first place, such as pussy willows, deciduous hollies or salt bush.
If drainage is not an issue, have the soil tested by a reliable testing laboratory. Do not spend your money on home soil testing kits. Let the test results guide you in correcting you soil.
The lesson here is, if your plants appear healthy and growing well, don’t fertilize them unless you enjoy pruning or shearing often.
Ask Dr. Gouin your questions at firstname.lastname@example.org. All questions will appear in Bay Weekly. Please include your name and address.