Are your posies looking peaked? Anemones anemic? Daisys in the doldrums? These are the dog days of summer and though our temperatures haven’t been all that stressful, most areas have had substantially more rainfall than usual for this time of year.
While, for the most part, the moisture has been helpful, heavy rains can wash away much of the available nitrogen, making it unavailable for plant uptake. A bit of supplemental fertilizer, applied alongside the plants, can rejuvenate your tired plantings.
Nitrogen is a plant nutrient that is used in large quantities by all plants, since it is essential for so many of the plant’s biological processes. In addition, the form of nitrogen that is taken up by plants is quite water-soluble. Because the nitrogen is so soluble, it can be quickly washed away during heavy rains or irrigation. This loss of nitrogen from the root zone is called leaching.
Containerized plants are especially vulnerable to leaching, since proper watering procedure calls for enough fluid to be applied so that some runs out of the bottom of the pot. This helps assure that water will moisten the entire soil area. But this method also washes some of the nitrogen away with each watering.
Plants that are becoming deficient in nitrogen will often look a bit pale, or in more serious cases, the leaves will turn yellow, beginning first with the older, lower leaves. If left uncorrected, the deficiency will begin to affect the new growth resulting in stunted, pale leaves. Though nitrogen generally is thought to promote foliage growth rather than flowers, plants that are under stress from lack of nitrogen may bloom sparsely or not at all.
To give your garden a “booster shot,” you can use a technique known as side-dressing. Carefully apply nitrogen fertilizer alongside existing plants and either scratch the material into the soil with a soil rake or hand cultivator, or water it down into the soil. The amount to apply varies with the specific product, formulation and plants. As a general rule of thumb, you can use 1/2 – 1 pound (1-2 cups) of 5-10-5 fertilizer per 100 square feet, but be sure to follow the label directions for your particular product. Be sure that any of the dry fertilizer is rinsed off of the foliage as soon as possible to avoid burning the plants.
For container plants, use a water-soluble product diluted according to label directions. You can either use a very dilute solution with every watering, or use a bit stronger solution once every week or two.