As long as daytime temperatures are moderate, it is a good time to fertilize plants in your ornamental and vegetable garden. When the weather turns hot, hold off on fertilizing. When plants are under heat stress, that push to grow worsens their problem.
If you haven’t started fertilizing your roses, start now, and fertilize once a month until August, then cease. Let the plants prepare to shut down for winter.
Most annuals don’t need much fertilizer, although some, such as Calibrachoa, need to be fed once a month. Unlike most annuals, this tiny petunia-like super bloomer doesn’t require deadheading. We deadhead (remove spent flowers) to encourage reblooming, and to prevent plants’ putting their energy into setting seeds.
Dr. Carolyn Male, author of “100 Heirloom Tomatoes for the American Garden,” says over-fertilizing tomatoes is the biggest mistake gardeners make.
She uses low-nitrogen fertilizers, such as 5-10-10 (nitrogen is the always the first number on a fertilizer container), so that the plant doesn’t put its energy into growing foliage instead of producing fruit. (The number 5 in this case means 5 percent of the bag is nitrogen; if it’s a 100-pound bag, there would be five pounds of nitrogen in the mixture, 10 pounds of phosphorus, 10 of potassium, and 75 pounds of “inert ingredients.”
She fertilizes tomato plants two weeks after transplant and again when fruit begins to set. For the amount of fertilizer, follow instructions on the fertilizer container or dilute it, giving less. In gardening, if a little is good, a lot is not better.
I’ve been putting a third of a trowel-full of granulated organic fertilizer in the planting holes of tomatoes and peppers, and shielding fertilizer with a layer of soil before inserting seedlings. That seems to be sufficient to give the plants a vigorous start, and to last the season. As they set fruit, I may supplement that with some fish and seaweed fertilizer, or better yet, Epsom salts (magnesium).
Magnesium is especially important in our area because our soils here in southwestern Idaho are deficient in magnesium. Correcting that deficit is fairly easy: spray leaves with Epsom Salts, mixed 1 teaspoon to a pint of water. Or mix about two tablespoons per gallon of water, and drench plants.
Nitrogen, phosphorus and potassium are the main elements we use to “feed” our plants, but they also require other nutrients in smaller amounts, including copper, boron, iron, calcium, manganese and magnesium.
It is quite common for us to talk about “feeding” our plants. We really don’t. Plants make their own food, photosynthesizing carbon dioxide, sunlight and water to produce carbohydrates and oxygen.
Plants emit some oxygen, and use some oxygen themselves to make carbohydrates that feed mycorrhizae fungi that in turn feed plant roots water, minerals and other materials needed to enable the plant to function correctly.
In a roundabout way, we do “feed” our plants.
SOME BUGS TO WATCH OUT FOR
Colorado potato beetles are out in our area. Watch for the pea-sized hard-shelled adults, tan or yellow with black stripes on their backs, heads orange with black spots. Adults feed on leaves and more importantly, lay eggs on undersides of leaves. Orange eggs are laid in clusters of about 25.
Larvae are reddish orange, with black dots on their sides, very rounded (larger than their parents), and they feel wet to the ungloved hand. They feed greedily on leaves unless stopped with rotenone, BT tenenbrionis (that has no effect on adults), traps around the edge of your potato patch (they don’t fly in, they walk), Pyola, Neem (although this may kill ladybug larvae too), or just hand crushing. Wear gloves.
Ladybird beetles, lacewings, spiders, and predatory stink bugs also feed on eggs.
These are called Colorado potato beetles because eastern Colorado was their original native range, where they fed on weedy buffalo bur. Once they got a bite of potato foliage, they fanned out across the country.
Margaret Lauterbach: melauter@earthlink.net or write to Gardening, The Idaho Statesman, P.O. Box 40, Boise, ID 83707
