- Author: Kathleen Craig
Have you ever wondered how to respond to gardening myths? Have you ever been giving a Master Gardener presentation and encountered the odd questions about a myth or worse yet, been awkwardly obliged to explain that helpful hints from an audience member are quite unscientific?
For me, yes to the above! There are so many sources of unproven information on the Internet, and unfortunately, most garden myths are not supported by science. We certainly don't want people leaving our presentations believing garden myths that they picked up from another attendee.
Here are some examples of garden myths and the science that debunks it:
Myth: Buried banana peels provide potassium to your plants.
Yes, bananas and their peels contain potassium which stimulates plant growth and flower production, however, the amount of nitrogen needed to break down the peel will mean less nitrogen is available for greening plants. What would be beneficial of course, would be to compost the banana peels and top-dress plants with compost instead.
Another garden myth recommends spreading crushed eggshells in the vegetable garden to cure blossom end rot with all that calcium that they leach into the soil. I did that before becoming a master gardener, and those eggshell chips are in the garden, unchanged, 3 years later. It turns out that unless the eggshells are ground into a fine powder and are put in an acidic solution, the calcium stays intact. Archaeological digs have actually found eggshells that have not decomposed. Also, in general, plants tend to not be calcium deficient in the first place
Myth: It is beneficial to use “natural” weed control mixtures such as baking soda, vinegar, and dish soap. While this recipe doesn't have traditional herbicides in it, it doesn't really kill weeds satisfactorily and adds a lot of sodium to the soil which is toxic to plants.
But wait…there's more! Put gravel in the bottom of your plant pots so the soil will drain better. Or better yet, put a sponge in the bottom of the pot! (This was a hint I saw in the Handyman magazine). What better way to keep your plant's roots moist and encourage root rot! Now I'm getting downright sarcastic!
The best way to get your plants to drain properly, of course, is to use well-draining soil and to water deeply and not too often according to the plant's water requirements. (The jury is still out on whether it's ok to line the pot with a coffee filter, or screening to prevent soil from being washed out when the plant gets watered. When surfaces change, it tends to disrupt the wicking action of water through soil, thus raising the water table and slowing the drainage.
Again, before I attended the Master Gardener training, I was game for trying some of the gardening hints I read. One of the worst ones that I fell for was putting ice cubes on your orchids in order to give them the “right” amount of water. The idea is that the ice cube melts slowly so the water drips into the soil medium and doesn't over-water the plant. This did nothing to improve my orchids. After reading up on the subject, I learned that since orchids are tropical plants and are unlikely to encounter an ice storm in their natural growing environment, putting ice on them would be a shock to the plants. One of my orchids survived, but now I water it deeply and less often, use fast-draining planting media.
The existence of gardening “experts” who follow old, unproven customs and continue to spread misinformation so frustrated some horticultural experts that they formed a group called the “Garden Professors”. They provide science-based information regarding the efficacy of garden myths. The group includes Fred Hoffman, and Linda Chalker-Scott and others. Their website is very helpful.
There are many, many web sites that cover this topic, but I have narrowed it down to just a few resources for you. When you encounter a question or opinion about garden myths, here are some quick and reliable references:
The Informed Gardener and The Informed Gardener Blooms Again by Linda Chalker-Scott