By Paul James
When I speak at gardening events across the country, the format I prefer is a simple Q&A. It engages the audience, it helps me understand exactly what gardeners are interested in, and it allows me to perform my shtick. It also gives me the opportunity to debunk common and persistent garden myths, including many that never seem to go away.
Newly Planted Trees Must be Staked
There are only two times to stake a tree. One is if it’s been planted as a bare-root tree and therefore lacks sufficient root mass to keep it upright. And the other is if you live on a hilltop where strong winds blow. Otherwise, there’s no real benefit to staking a tree. Ideally, trees should be left to sway in the wind because that helps them develop stronger trunks. If you do stake a tree, remember to remove the stake after the first year.
Stressed Plants Should be Fertilized
When a plant looks sickly, your first instinct may be to fertilize it. But that’s often the last thing you should do. A plant in poor health absorbs fewer nutrients than a healthy plant, so adding fertilizer can actually backfire by leading to an accumulation of excess nutrients and salts in the soil that can burn tender roots and cause leaf discoloration.
Instead, you should first try to zero on what the real problem is, including pH imbalance, pest or disease problems, drainage issues, poor watering practices, and so on, all of which can inhibit the absorption of nutrients, making the addition of fertilizer a complete waste of money.
Add Gravel to Bottom of Pots
This one’s been around for years, unfortunately. The idea behind it is that gravel at the bottom of the pot improves drainage and reduces the likelihood of root rot. But in fact, it actually increases the chance of root rot, because water doesn’t move easily through the potting mix to the gravel. As a result, water builds up in the potting mix and is only released into the gravel when it’s saturated, like a sponge that can’t hold any more water. So when planting things in a pot, use only potting mix.
(The technique, by the way, is known as crocking, and soil scientists have known for over a hundred years that it doesn’t work. Said another way, crocking is a crock.)
The idea behind the use of pruning paints is simple enough: the cut surface of a stem or branch is like an open wound, and by sealing the wound the threat of rot or disease is eliminated. But in fact, pruning paints actually increase the threat by interfering with the natural healing processes.
When a stem or branch is cut, trees form scar tissue to keep pathogens out. Not only do pruning paints prevent the formation of scar tissue, they can also seal in water along with various pathogens that can lead to decay.
Amend Clay Soil with Sand
If you mix clay with sand and add water, you get something akin to a brick, and that’s not a good thing, unless of course you’re building a home. In the garden, the only way to improve clay soil is by adding organic matter – compost, shredded leaves, grass clippings, barnyard manures, and so on. It may take several seasons and repeated applications to truly transform a clay soil into something akin to loam, but you’ll get there.
Organic Pesticides aren’t Chemicals
It’s common these days for people to refer to natural pesticides as “organic” and synthetic pesticides as “chemicals.” But that’s ridiculous, because all pesticides are chemicals. Period. Organic products are derived from natural sources (such as plants, animal byproducts, and bacteria), whereas synthetic products are manmade. But they’re all chemicals, and there’s no getting around that fact.