Gardening Advice or Myth (GAoM): Weeding out Fact from Fiction
Submitted by ~ Suri Lunde
Below are a few gardening advice/myths that we often hear but may or may not be solidly rooted in science or actually work.
GAoM 1: Compost adds lots of nutrients to soil.
It is true that adding sufficient compost into gardens makes plants grow well, which somehow implies that compost must be adding nutrients to our soil. In reality, compost has dismal nutrient levels: an N-P-K analysis of 1-1-1 or less. What compost actually does is help plants grow better in low nutrient environments by increasing the population of bacteria and fungi in the soil. These bacteria and fungi take the not-fully decomposed matter in the compost and convert them into specific nutrients the plants need to grow. So go ahead and apply lots of slow-made well-aged compost regularly and create a perfect habitat for the bacteria and fungi so that they do your fertilizing.
GAoM 2: Gravel in the bottom of containers helps drainage.
It is standard practice when filling a container to place gravel stones or pieces of pot at the bottom ‘for drainage’. This actually restricts plant growth because it has less space, and also results in roots sitting in water. Water clings to soil particles until it is completely saturated, then drains away. A layer of gravel at the pot’s base only collects that water and shifts the pool of water higher up the pot, making the roots sit in it and causing root rot. As long as there is a hole at the bottom of the container, water will find its way out without the need of gravel.
GAoM 3: Always plant marigold in the garden.
Many gardeners plant rows of marigold along their vegetable patch or as a companion plant because marigold repel many garden pests and insects. Marigold helps reduce, not eliminate, nematodes (microscopic worms) in the garden. Although many nematodes are beneficial (e.g. they help kill June bugs in lawns), some nematodes invade plant roots and cause deformities in root crops like beets and carrots. Marigold acts as a repellant for nematodes: its natural nematicides kill the nematodes, and chemicals released by its roots prevent nematode eggs from hatching, thereby decreasing the nematode population. The marigold’s fragrance does not play any part in attracting or repelling nematodes or any other pest – that is a myth.
GAoM 4: Watering plants in the afternoon sunlight burns leaves.
The belief is that water acts as a magnifying glass, focusing the sun’s rays as they hit the water, causing ‘leaf burn’. If this is true, farmers would suffer massive losses after each daytime rainstorm! Using computer modeling and live tests, scientists have proven that water is not powerful enough to magnify the sun’s rays to the required heat needed to burn the leaves on plants. Generally, the best time to water most outdoor plants is early in the morning but if watering in afternoon sunlight is the only option, it will not harm plants.
Conclusion: Let’s promote truthful gardening wisdom and debunk gardening myths. By letting unequivocal gardening myths die, we all gain a better way to grow showy perennials, overflowing hanging baskets, and bountiful vegetables.