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A common misconception is that all landscape plants need to be fed regularly. One of the most common questions visitors and callers ask Minnetrista gardeners for is a range of advice on what kind and how much fertilizer should be used.
I can usually tell by the reaction of the visitor or caller that they didn't expect the given answer. I tell them that I don't know and the only way to know for sure is to do a soil test.
What does testing your soil provide?
? Accurate information on what, if any, nutrients your soil is lacking. Not just the macro nutrients that many people are familiar with like N, P and K, but other important macro and micro nutrients like zinc and boron.
? A pH reading, which is important because some nutrients aren't available at certain pH levels. An example of this would be iron, and adding it to your soil does little for long term changes in plant health if you have high ph.
? Saving you money. If you find out you don't need any fertilizer, you won't be applying unnecessary nutrients that cost money.
? An environmentally responsible practice. Over-applied nutrients don't stay on site and will move toward ground and surface water, like lakes, rivers and streams. This causes a host of issues, from excess weed growth to algae blooms, and can be dangerous to human health.
This advice does change when considering annuals or vegetable beds that have the plant material removed each year. By removing the plant material, you prevent nature's way of recycling nutrients from happening and will lower nutrients levels overtime. Composting removed plant material and returning it to the garden as a top dressing is a great way to prevent nutrient drain.
One other note about soil tests is that you will most likely not have a nitrogen value. Nitrogen levels fluctuate in the garden and are often the most limiting macro nutrient in landscapes.
Dustin Stillinger, an ISA Certified Arborist, is the Horticulture manager at Minnetrista overseeing twenty-one acres of ornamental and natural areas. He can be reached at (765) 287-3563 or firstname.lastname@example.org.