"I really expected eggshells to be the best thing ever," said the associate professor of horticultural science at the University of Minnesota.
In his book, "The Truth About Garden Remedies: What Works, What Doesn't and Why," Gillman shares his experiments and research.
Even after his book was published, Gillman has continued to try to stop slugs in their tracks. He has found that dryer lint isn't effective, and copper is only marginally effective. Chewing tobacco kills slugs with a vengeance, but he doesn't recommend it because it isn't organic and can carry viruses.
Here are more findings:
Dish soap solutions
Common remedy: Spray a solution of dish soap and water on plants to kill bugs.
The real story: Such homemade solutions, usually 1 to 4 tablespoons of dish soap per gallon of water, do kill aphids and other soft-bodied insects. The wax cuticle on the insect's body is washed off so it dries up and dies. However, the soap solution also hurts the plant by removing the protective wax coating on its surfaces. Most harmful are antibacterial soaps.
What works: Commercial insecticidal soaps are safer.
Added drainage
Common remedy: Cover the bottom of plant containers with pebbles, gravel or shards of pottery to improve drainage and prevent root rot.
The real story: Water doesn't move easily from the finer textured potting soil through the coarser materials on the bottom.
What works: Add some perlite to the soil for better drainage.
Planting deep
Common remedy: Plant trees and shrubs deeply, so that a few inches of soil cover the uppermost root. That ensures roots receive enough water and plants are stable in high winds.
The real story: If the tree or shrub doesn't die from too much water, the roots will grow upward to get needed air and strangle the plant. Diverted root growth makes the tree or shrub less stable.
What works: The top of the roots should be visible at ground level around the trunk. Added mulch shouldn't touch that root stem because roots could grow up into the mulch.
Eggshells
Common remedy: Crushed eggshells stop slugs.
The real story: A ring of finely crushed eggshells around plants such as hostas inhibits but doesn't repel slugs. Larger eggshell pieces are even less effective.
What works: Diatomaceous earth repels slugs by tearing their bellies as they crawl over it. Iron phosphate also works. Beer traps sunk into the ground catch and drown slugs.
Soap bars
Common remedy: Hang bars of soap from trees to repel deer.
The real story: Bar soap keeps deer away, but only for an area about three feet from the soap. No particular brand works better than another.
What works: Homemade repellents, especially those containing rotten eggs, and commercial repellents can work for short periods when deer aren't feeding intensely and in great numbers.
Hydrogels
Common remedy: Hydrogels added to potting soil absorb water and then release moisture to plants as needed.
The real story: Hydrogels don't work very well, nor consistently. They hold water but the moisture isn't necessarily transferred to the plant.
What works: Hydrogels will keep a plant from drying out when it's removed from the ground with little soil left on the roots for transplanting. Dipping the roots in a bucket with hydrogels will help keep the roots from drying out until replanted.
Tree wraps
Common remedy: Wrap the base of young thin-barked trees with aluminum foil, plastic or a heavy paper to protect them from cracking from sun scald or being damaged by insects, rodents and rabbits in winter.
The real story: Not all trees need wraps. While they can repel boring insects, they also can increase damage if insects live between the tree and the wrap. Girdling can result if the wrap is left on more than six months. Paper wraps don't help protect from cracks from frost and sun scald, though a lighter-colored material is more effective.
Mouthwash
Common remedy: A solution of mouthwash and water sprayed weekly on plants controls powdery mildew and other diseases.
The real story: a solution of 1 cup generic mouthwash and 3 cups water applied weekly to plants does control powdery mildew and black spot. But the alcohol in mouthwash causes leaves on young rose plants to curl.
What works: Commercial fungicides work better. |
