Fact or fiction? Debunking 10 yard and garden myths

Don Kinzler
Forum News Service

FARGO, N.D. — I’m often asked if gardening information is true, or if it’s “an old wives’ tale.” As I’ve often said, I’m never quick to dismiss old wives’ tales, because some of the best gardeners I’ve ever known have been old wives. And plenty of old husbands have told a tale or two.

Did you see the internet article claiming you can tell a female pepper from a male pepper in the grocery store, and one is sweeter? Can you really prevent weeds by sprinkling cornmeal over the soil?

Let’s examine the reality of some common yard and garden myths.

Myth 1: Adding a layer of rocks or pebbles in the bottom of houseplant pots is necessary for proper drainage.

Reality: For over 100 years, soil scientists have demonstrated that water does not pass easily from a layer of soil into a layer of coarse material below. Water first supersaturates the potting soil before exiting into the rock layer, increasing the chance of overwatering houseplants. For best drainage, just fill the pot with high-quality potting mix, and skip the layer of pebbles.

Myth 2: Applying pruning paint or sealers to pruning cuts or injuries will help the tree’s wounds heal.

Reality: Trees have the natural ability to recover from wounds, as they’ve done for eons. Applying paints or sealers can interfere with the formation of the tree’s natural protective tissue, while causing moisture and rotting organisms to flourish under the artificial coating.

Myth 3: When planting trees and shrubs, amend the soil with compost or other organic material, so the plant has better soil in which to grow.

Reality: Adding ingredients to the planting hole or backfill soil creates an area that is overly favorable, causing roots to remain within the planting hole, instead of growing outward into the non-amended soil. Instead, simply backfill the planting hole with the surrounding natural soil.

Myth 4: Ants are necessary for peony buds to open properly.

Reality: Researching this is easily done by simply excluding ants from a peony, showing that flowers open normally without ants. Ants are attracted to the bud’s sticky sap, so although ants aren’t necessary, they’re usually found in close association with a peony that’s blooming nicely.

Myth 5: When shopping for bell peppers, choose female peppers, identified by the four bumps on the base, as they are sweeter. Male peppers have three bumps.

Reality: There’s no such thing as male and female pepper fruits. All pepper fruits result from the pollination of the female ovary, so all peppers and other fruits are ripened ovaries, by definition. The number of bumps on bell pepper fruits are random, usually caused by growing conditions.

Myth 6: Cornmeal will prevent weeds if sprinkled over the soil.

Reality: A product called corn gluten meal might have limited benefit in some weed suppression, but that’s a different product. Grocery store cornmeal does not prevent weeds.

Myth 7: Adding Epsom salts to the soil prevents blossom end rot of tomato fruits.

Reality: Blossom end rot is caused by the plant’s inability to temporarily access soil calcium, which is plentiful in our soil. Epsom salts contain magnesium, and have been shown ineffective. If the application of Epsom salts has seemingly worked, it’s coincidental, and it isn’t recommended as it can cause other soil problems.

Myth 8: Applying acid-based materials to our alkaline soil will turn hydrangeas from pink to blue, and help us grow maples and blueberries.

Reality: Attempting to acidify our region’s natural alkaline soil is like trying to change the color of the ocean by adding food coloring.

Myth 9: Newly planted trees should be staked.

Reality: You find very few trees staked in nature’s forests. Trees develop stronger tissue if allowed to bend naturally in the wind. If needed to stabilize a newly planted tree, stake loosely, and only for one growing season.

Myth 10: Landscape fabric will prevent weeds.

Reality: Weeds can eventually germinate in the soil slivers that accumulate in rock mulch, and easily in wood product mulches. Weeds root readily down through fabric, making removal difficult. When fabric is used, vigilance is required to attack weeds while tiny.

Fielding questions

Q: In looking for LED lights to start seedlings, I notice some types give off bluish-red light, while others give off white light. Which is better for seedlings? — Bob M., Casselton, N.D.

A: Seedlings grow well under both LED and standard fluorescent lights, with LED being more economical to run, although the initial cost of bulbs is usually greater.

Science classes taught us that natural sunlight is a combination of many colored wavelengths, and together they appear white. Green leaves reflect and derive little energy from yellow and green light wavelengths, while red and blue wavelengths are the most important energy source for plants. Plant lights emitting red and blue light are attempting to provide more of what plants need.

Here at our North Dakota State University Extension office in Cass County, we’re doing a homeowner-type test of both white and red/blue colored lights for growing seedlings. So far, the results are about the same, but reports indicate that some plant types will prefer the red/blue.

From a practical standpoint, though, the purple-colored lighting produced by the red/blue bulbs is very difficult in which to work. I much prefer working with seedlings under a white-toned light. As a compromise, if a fixture holds two tubes, select a warm white and a cool white for a broader light spectrum.

Q: Should we be using something other than tap water to water our houseplants? — Mae Tinguely, Fargo.

A: Whether to use one’s tap water depends on the source of the water. For example, if a rural home’s plumbing uses water from a well, it might contain minerals that could build up in potting soil, depending on the analysis of the well water. Or if municipal water contains fluorine and chlorine, the tips of some susceptible plants often burn.

If water is purified primarily by ozone instead of chlorine, like Fargo’s water, then there isn’t the problem of chlorine salts accumulating, although the fluoride added to most drinking water still can contribute to leaf tip burn. If water is chlorinated and fluorinated, allowing it to sit overnight might help somewhat, although the actual benefit has been debated.

Rainwater and melted snow are great sources of naturally “soft” water. One type of water to absolutely avoid is water that has been softened through a water-softening unit. The salts added during the softening process quickly accumulate dangerously in potted plants.

Occasional “leaching” or flushing of the soil by repeated watering can help remove harmful chemical buildups in potting soil, as does repotting more frequently if one’s water source is less than ideal. If one has a small quantity of plants, or a plant of special value, distilled and reverse-osmosis water are good choices also.

Q: When pellets used for melting ice dams run off your roof, do they damage plants if used in normal levels? —Tim Flakoll, Fargo.

A: Great question, as our roofs have plenty of snow and ice again this year. Whether snow and ice melting products damage plants depends greatly on the ingredients of the product used.

Products containing sodium chloride are quite damaging to plants, and are responsible for many patches of dead grass along sidewalks and boulevards. When investigating products used to melt ice dams on roofs, I’ve found many contain calcium chloride as the melting agent. University of Minnesota, Purdue University and many others indicate that calcium chloride is much less damaging to plants than sodium chloride, making it a safer choice. In some ice dam melting systems, the calcium chloride is located in a “sock,” which helps minimize product runoff.

Any of these chloride-based chemicals can adversely affect plants, but look at the ingredients and select calcium chloride instead of sodium chloride when possible, to lessen the chance of plant damage. If you can, guide runoff away from landscapes and plant material.

This edition of “Growing Together” discusses common gardening myths.