Many high-phosphorus fertilizers for transplants should not touch the leaves of plants. But what kind of technique can I use when I must apply these fertilizers to delicate, low-growing plants, where it is impossible to lift the leaves enough to let the fertilizer flow underneath them?
Ursula Chautems, Pierrefonds, Quebec, ca
Paul Sachs, owner of
North Country Organics
in Bradford, Vermont, replies: Most conventional fertilizers for transplants are made with either superphosphate or triple-superphosphate. These ingredients can burn foliage because they are made with acid. Ammoniated phosphate, ammoniated nitrogen, and nitrogen salts can also burn leaves.
The simplest way to apply conventional fertilizers to low-growing plants is to water them in. Sprinkle the fertilizer as close as you’d like to the plant, then water the plant to wash the fertilizer off. The fertilizer won’t burn the leaves right away, but it is a good idea to wash it off within 15 minutes. If you don’t want the fertilizer to touch the foliage at all, apply it farther away from the plant than you normally would, keeping away from the low-growing leaves. Most perennials’ roots have no trouble finding the phosphorus, even if it is a little farther away.
Another solution is to use a fertilizer made with natural rock phosphate or bonemeal. These ingredients won’t burn the leaves, so you can put the fertilizer right under the plant. Even though these natural fertilizers act much slower than conventional fertilizers, they will supply the necessary phosphorus. One caution with both the rock-phosphate and bonemeal fertilizers: They can raise your soil’s pH if used in excess.