Purdue Extension Service

Vanderburgh County, Indiana

Myth-Information in the Garden

By Larry Caplan, Extension Horticulture Educator, Vanderburgh Co., IN

For the Evansville Courier and Press, January 6, 2008

There are many myths and misconceptions about gardening. Some of these are based on folklore, or incomplete knowledge of the science behind a gardening practice. Let’s look at a few common garden myths, and the truth behind them.

Myth #1: Marigolds repel pests. Data from reputable university research shows no such affect. However they do attract beneficial insects which may feed on pests.

Myth #2: Ants on peonies are necessary to allow the buds to open. Nope, they are just feeding on the sticky sap produced by the buds. They do no harm to the flowers but they may attack peony pests.

Myth #3: Gypsum will “loosen” clay soil. This is true only if you have soil where sodium, instead of calcium or magnesium, saturates the clay. In these “sodic” soils, gypsum causes soil particles to gather together, improving structure and water infiltration. Unless you’ve had a spill of salt or brine on your property, gypsum will have no effect on southern Indiana soils; organic material such as compost is your best soil amendment.

Myth #4: Pruning sealant helps wounds “heal”. This was based on the premise that a covering of pruning paint or tar protects the cut surface from decay. In reality: wood-rotting organisms may already be in the surface, so you are just trapping them in. The coating can crack leaving the wound even more susceptible to decay. This coating may also actually inhibit the callus formation on the wound, slowing the natural protective process. The bottom line - prune at the proper time for the type of plant, make appropriate pruning cuts, and let the tree protect itself.

Myth #5: Buy the biggest plants you can afford to get a jump on growth. Research has shown that a 2 inch diameter tree will catch up to (and often surpass) a 4 inch diameter tree within a few short years. Ohio State research showed that tomato seedlings that are already fruiting when transplanted yield poorly, even if the fruits are removed.

Myth #6: Moss growth in lawns shows a need for lime.  This is not necessarily true. Acidic conditions could be responsible for moss crowding out your grass, but so could excessive shade, poor drainage, low fertility, and a host of other causes.  When conditions do not favor healthy turf, moss can take over.

Myth #7: When it comes to garden chemicals, if a little bit is good, a lot is better. This myth is not only false but dangerous. Weed killers used in this manner can injure plants you never intended to harm.  Over-use of insecticides may kill beneficial insects, injure plants, and render vegetables unfit for consumption.  Using more of any pesticide than the label states increases the chances of human poisoning, as well as being illegal.

Fertilizers used too heavily will burn plants, prevent seed germination, and contaminate water resources.  Even organic fertilizers such as manure can cause harm if you use too much.

To learn more about the truth behind gardening practices, contact the Purdue Extension Service at (812) 435-5287.