Everything You Know is Wrong, Cont.

Besides being the title of an excellent Firesign Theater album from 1974 that was a parody of popular New Age practices at the time, "Everything You Know is Wrong" can also apply to gardening. It seems the "right thing to do" in the yard tends to change over time. 

Perhaps your grandparents (or your parents or you) would regularly spray tomato plants and other garden vegetables with DDT or Diazinon. Try finding either of those deadly pesticides for home use in the U.S. in 2010!

In the 1950's, here in  Northern California, the Modesto ash tree was considered the perfect street tree: it had a nice umbrella shape, grew quickly, nice fall color and seemingly resistant to pest and disease problems. "Seemingly" turned into "not" within 20 years. Anthracnose (pictured to the right), aphids, mistletoe, borers...it turns out that those stately Modesto ash trees are so problem-ridden, you can't even find them in nurseries anymore here.

And there are plenty more gardening methodologies that should be headed towards the green waste container. That's according to Dr. Linda Chalker-Scott, horticulture professor at Washington State University and overseer of the excellent website, "Horticultural Myths".

In 2009, Chalker-Scott won the Best Garden Book of the Year award from the Garden Writers Association for "The Informed Gardener", a compendium of many of the garden myths exploded at her website. Chalker-Scott approached many commonly accepted gardening practices from a scientist's point of view: "Prove It!" 

Calling on the resources of Universities and scientific studies (all peer-reviewed), Chalker-Scott blew holes in several common gardening habits, including:

Using tree sealants on pruning cuts (that actually slows the healing process)

Adding drainage materials to the bottom of plant containers (that hinders water movement)

Adding sand to clay soils to improve texture (the undesired result is a heavier, denser soil with less air)

Chalker-Scott is back in 2010 with a follow-up edition, "The Informed Gardener Blooms Again". This time, she takes on many popular gardening practices that are revered by adherents of sustainability, organic gardening and drought-resistant gardens. 

Among her findings:

Many organic gardening practices based on folklore do not stand up to scientific review. 

• Whipping a tree trunk will not make the tree grow faster.

• Burying open coffee cans to aid "deep watering" wastes water and ignores the feeder roots.

• The addition of Epsom salts will aid plant growth? No scientific evidence of that, she says.

The addition of seaweed extracts will not reduce plant disease or increase production. In actual field conditions, seaweed extracts have no reliable effect. Their use represents, she says, a waste of a natural resources in our threatened coastal ecosystems.

Your "drought-tolerant" garden may be using more water than a regular landscape. If more water is available, drought tolerant plants will use it, becoming more lush...a sought-after goal of many gardeners. An attitude change must be implemented by homeowners, who must be willing to accept smaller, less vigorous plants in a xeriscaped garden.

Other myths explored and exploded by Chalker-Scott include:

• using bleach to disinfect your pruning tools;

• the use of gypsum;

• rubberized landscape mulches;

• and, why buying ladybugs for your garden is a bad idea.

Many will disagree with Chalker-Scott's research-based findings. Still, the evidence is worth reading, especially if your only line of defense is, "Hey, it works for me."