MANHATTAN, Kan. – Many landscape plants can put a fertilizer meal to best use if they get it in early spring, according to horticulturist Ward Upham.
“Fertilizer choice and rate can be as important as timing, though -- particularly in the central High Plains. Around here, excessive amounts of nutrients can be far worse than a deficit,” said Upham, the Master Gardener program coordinator for Kansas State University Research and Extension.
Early spring is when plant roots gear up to expand for the growing season, as well as to support new leaf growth, he explained. So, roots can quickly put a little extra food to use, promoting stronger, greener perennials, hardy bulbs, vegetable plants, and deciduous trees and shrubs.
“You don’t necessarily need to feed every plant every year. Once established, for example, most perennials and many ornamentals aren’t exactly what you’d call heavy feeders,” Upham said.
In general, food-producing and annual plants are most likely to need regular meals, he said. Among the landscape staples that can benefit from an annual, pre-flower meal are the astilbe, chrysanthemum, delphinium, lupine, summer phlox and hardy bulbs (daffodil, tulip etc.).
Upham rarely recommends using a balanced fertilizer (e.g., a 10-10-10 or 9-9-6) to feed any kind of in-ground plant. Many Kansas soils have enough phosphorus (P) and potassium (K). And, a soil test is the only way to discover if a particular yard has developed a P or K deficit.
Most soils can get low on nitrogen (N), however, because plants use a lot it. Besides, misapplied N fertilizers easily convert into a gas. Gardeners can lose up to half of a urea application, for example, if they don’t incorporate it into soil immediately. Plus, runoff can easily carry unused N away – often into a storm drain system and on to pollute a nearby natural body of water.
“If you don’t have soil test results, consider using urea, alfalfa meal, blood meal or even compost as a nitrogen supply for your crocus and chrysanthemum plantings. Or, as an alternative, apply a nitrogen-heavy turf fertilizer (e.g., a 27-3-3 or 30-3-3) -- but only if you follow label directions exactly. Too much nitrogen can cause excessive leaf growth and in severe cases will burn plants much as drought does,” Upham said.
Source : K-State Research and Extension