Horticulture Myths

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Horticulture Myths

"As a horticulture educator, it is my duty to dispel horticulture myths," says University of Illinois Extension Horticulture Educator, Kelly Allsup.

Myth:Some mulch is good. A lot of mulch must be better. I am referring to the sad, but familiar, mulch volcanos around the base of trees. Leaving mulch up against the tree will cause the bark to decay, cut off the water conductive tissues, and can promote a slow death. This stressed tree is ideal for insect borers and poor root growth.

Truth:Add 2 to 4 inches of mulch around the base of the tree, but leave about an inch free around the bark of the trunk. Create as large of a ring as possible, as roots will extend out 2 to 3 times the width of the canopy. You may not have the area to reach the ideal size, so the larger the better. Mulching trees is an ideal fall gardening task.

Myth:Add layers of rocks to the bottom of a pot to improve drainage. Adding these two very different textures makes the soil act like a sponge, absorbing every drop of water and not allowing the water to drain out into the rocks, creating anaerobic conditions closer to the roots that you are trying to grow.

Truth:Use the highest-quality container soil that you can find. If you want to add an element to make the pot lighter or improve drainage, then mix perlite or vermiculite in your soil. To prevent soil from coming out of the drainage holes, add coffee filters, newspaper or paper towels.

Myth:All pesticides are bad.

Truth:There are many biological pesticides on the market made out of naturally derived materials. For instance, BotaniGard (Mycotrol) is fungus that naturally grows in soils. The active ingredient is Beauveria bassiana, which acts as a parasite on certain insects like beetles, whitefly and thrips.

Neem oil is found in the seeds of the neem tree. The active component found in this biological pesticide reduces insect feeding, interferes with hormones -- making it hard to grow or lay eggs -- and acts as a repellent.

Despite these being biological pesticides, it is important to read the directions on the label and wear safety equipment. Because they are biological, they may not be as fast acting or control as large a percentage of the population. Follow up three to 10 days later to investigate if beneficial insects have come in or if another spray is required.