It's said that beer can be fertilizer for plant. Wow! It's so amazing but is it true??? According to Jeff Gillman, an associate professor in the Dept. of Horticultural Science at the University of Minnesota, he has done the scientific research himself. Beer does, however, get a four-flower recommendation as a slug killer, so long as the traps are set up not only to attract the slugs but to catch them as well. In the fertilizer department, eggshells are a five-flower solution, although they shouldn't be your only source of fertilizer. The author suggests four to five crumbled shells per plant, mixed into the soil around the plant, in the garden or in a pot.
Most of us are familiar with the practice of some gardeners who sprinkle today's used coffee grounds around their plants as additional fertilizer or as a soil acidifier. Dr. Gillman indicates that, to have any impact on the plants, the coffee grounds must be incorporated into the soil. Further, he says, not every plant benefits from the addition of coffee grounds; lettuce benefits quite a lot, while tomatoes do not. There are better soil acidifiers.
One theory around since the early 1900s suggests that it is beneficial for good pot drainage to have a layer of gravel covering the bottom of the container. To my surprise, Dr. Gillman illustrates how this practice actually increases the amount of water in the growing medium above the gravel, as well as hindering the movement of water from the top of the container through the gravel and out of the pot. His advice is to use a good-draining medium in the entire pot, adding perlite if you think it necessary to have even better drainage.
The practice of using dish soap to control insects has been around since the 1700s. He even cites a recipe for a mixture of urine and soap from the early 1800s for getting rid of aphids on melons. Dish soap is thought by many gardeners to be effective in washing off the waxy covering of insect bodies at a fraction of the cost of commercial insecticidal soaps. Unfortunately, the commercial insecticidal soaps have been specially formulated to protect the waxy cuticle of the plant; dish soap has not, and can cause wax removal, leading to loss of water, leaf scorch, and death of the plant. The author's conclusion is that, without first testing your dish soap on plants you are willing to sacrifice, you are playing Russian roulette; moreover, today, more and more soaps are antibacterial and even more harmful for plants than the old-fashioned variety. This is certainly an instance when the extra money spent on a commercial product is money well spent.
By Madeline Wajda