Garden wisdoms, myths debunked

As in many human endeavors, urban myths or “old wives’ tales” are in abundance when it comes to the study of horticulture.

Some are more obvious than others, while some need scientific reflection.

An urban myth is a form of story usually believed by the teller to be true, whereas an old wives’ tale is a type of legend or proverb, which is generally passed down through the generations.

Robert Pavlis, M. Sc. (Biochemistry), logically discussed the topic of Gardening Myths with the Fergus Horticultural Society.

In 2005, he purchased a large property, south of Guelph, and developed Aspen Grove Gardens. That large site has mulched perennial beds, wet and dry waterfalls, and numerous flora collections for both sun and shade.

Pavlis is a master gardener, author, contributor to the Vineland research blog and has had impressive collections of orchids, roses and daylilies over his 30 years of gardening.

His approach to gardening is common sense by letting nature take its course.

During his presentation, he pointed out that they should “save their money” and not continue to follow certain practices.

Always choose natural products in gardening: The words “organic” or “natural” are marketing ploys and not always better for a garden. Some so-called organic compounds are more toxic than their chemical counterparts.

“Botanical natural pesticides that are toxic to garden pests and harmless to other living things, including gardeners, is simply not true,”, said Pavlis.

He explained further, “Some botanical pesticides that are derived from poisonous plants are even more toxic than commercially prepared ones”.   

As a master chemist, he reviewed the properties of a plant that is commonly used in the celebration of Thanksgiving. The chemical created is pyrethrum made from chrysanthemum cinerariaefolium.

When commercially used, pyrethrum rapidly knocks-down and kills a wide variety of insect pests such as cockroaches, mosquitoes, fleas, and houseflies. It is also widely used in gardening for the control of leaf hoppers and other pests.

Pavlis cited rotenone as another “natural” compound produced by the roots of the leguminoceae family. It controls leaf eating caterpillars, beetles, aphids, and thrips.

Pyrethrum and rotenone are moderately toxic to humans, particularly children when inhaled or ingested.

Cats are particularly susceptible to poisoning from pyrethrum.

Pine needles make soil acidic Many gardeners believe soil beneath pines is too acidic to grow plants. However, pine needles, though slightly acidic in their raw form, have no more effect on soil acidity than does normal rainwater.

In addition, when aged and dried, pine needle mulch, known as pine straw, makes a more effective mulching agent than conventional wood chip mulches.

Lawns that have moss, require lime Moss will grow anywhere there is an open space. Too much shade, wet conditions, poor fertility or compacted soils are all conditions where lawns do not grow well but will permit moss to grow. Do not add lime to correct a moss problem unless a soil test indicates an excessively acidic result.

Poinsettias are poisonous   That popular myth is false. There are no cases of plant poisoning from poinsettias. Each year around Christmas, the Society of American Florists demonstrates that point by eating some leaves of the poinsettia. The leaves are bitter but won’t kill people, just make them ill. In reality, the plant should not be eaten and is hazardous because of the milky sap. The sap can cause an allergic reaction in some people.

Certain plants can repel mosquitoes Amazing but untrue, there are no plants that repel mosquitoes. If you rub the leaves of certain plants onto your skin, the oils and aromas can help discourage mosquitoes from biting. It is asking a lot of a plant to release essential oils into the air in quantities that can keep mosquitoes away for distances like two metres.

Hostas are shade dwellers that can’t tolerate the sun  There are many hostas that perform very well in the sun if they are given adequate moisture. In fact, the native habitat for many hostas is in a sunny location at the edge of the forest. Some hostas that tolerate more sun are: Francee, Patriot, Sum and Substance, Gold Standard and Royal Standard

Some gardeners follow the advice given over the backyard fence without really knowing if it is based on scientific information. Gardening is a branch of horticulture that is based on proven facts.

Ron Stevenson is a member of the Fergus Horticultural Society