T’is the season when many gardeners are thinking about soil tests. Especially in instances when plants won’t grow, won’t flower or won’t respond to our best efforts, soil tests can be the logical next step.
Bear in mind, however, that while the soil test results contribute to an overall understanding of the health of the soil, the results will likely not fill in all the gaps as to why some plants don’t thrive. Take, for instance, the fellow who was frustrated when he was unsuccessful at growing a lawn beneath his trees. The grass seed would germinate; the seedlings would grow for a little while and then die. Once he understood that even shade-tolerant grasses need a minimum of 3 hours of direct uninterrupted sunlight daily, he realized the spot was just too shady and a soil test wasn’t what was needed.
Then there was the blue-flowered hydrangea that refused to flower. Determining the shrub was not in a protected spot for the winter, it became clear the flower buds were dying over the winter months resulting in no flowers or very late flowers during the growing season. Again, the gardener realized it wasn’t an issue of bad soil but instead flowering wood that didn’t survive the winter.
A routine soil test won’t indicate residual herbicides lurking in the soil. There are specialized soil testing labs for this type of soil testing and the search won’t be a low-cost item.
There are many times when a soil test does aid the gardener—like when determining if the lead levels in the soil are dangerously high and eating vegetables and fruits from the garden pose health risks. This is especially true when vegetable gardens or orchards are sited close to buildings that were painted prior to 1979, when lead was added to paint. As the lead paint flakes away, soil lead levels increase.
Another good reason to have a soil test done is when rainfall leads to standing water. These areas can be magnets for mosquitoes to lay their eggs, so an understanding of why water doesn’t percolate through the soil would be helpful.
Sometimes, the gardener just wants to know the nutrient levels, pH, and organic matter content of their soil, in which case a soil test is the perfect way to understand these components.