A friend who worked at the Foxfire School in north Georgia many years ago remembers children who were sewn into their long underwear at the beginning of winter and not cut loose until spring. The school rooms and homes in that poor, remote part of the world were so cold that bathing wasn’t considered a necessity.
Most plants in our landscape go into a kind of long underwear mode in winter time. Their growth rate slows dramatically. Extension agents remind clients to use irrigation systems far less often, with only newly planted shrubs and trees needing a weekly shower, be it natural or artificial.
Dormant plants, like hibernating bears, live off stored nutrients and don’t require extra feeding. Not only is winter fertilization unnecessary, it can be harmful.
Plants take nutrients from the soil solution (water) by a variety of chemical and physical actions. In the down time of winter, these processes slow down dramatically. Fertilizers you apply too early are going to sit in the soil until rains leach them into the moisture table or they wash off your property, down the street, and into the storm drain. As Clemson’s Carolina Clear is making crystal clear in its educational programs, fertilizer in the wrong place is a pollutant.
When these dissolved fertilizers end up in ponds, lakes, or rivers the photosynthesizing algae living in that water use those nutrients to increase their population. Eventually they will scarf down every last nitrate or nitrite and then starvation, death, and decay come. At this point, decomposer micro-organisms, which require oxygen for respiration, chow down on those million zillion dead algal cells, the dissolved oxygen level drops below what the fish need, and you have a lake full of floaters.
The rule of thumb for fertilizing trees and shrubs in South Carolina is to apply nutrients in mid-March. Lawns are slower to start active growth and don’t need their annual spring tonic of nitrogen, and/or phosphorus and potassium until after April 15.
Nitrogen is exceptionally short-lived in soils, and unless you are supplying it through top dressing with compost, you’ll need to add some for healthy growth. Other nutrients, however, especially phosphorus, may already be at optimum levels. Many places in the U.S. mandate sales of phosphate-free fertilizers as their surface waters have high levels of this nutrient from runoff.
Please take a soil test to determine which and how much of these nutrients your plants and lawn need. Clemson’s Home & Garden Information Center has a fact sheet on soil testing, and Clemson’s Carolina Clear program is offering a dandy magnet for your mailbox tooting your eco-friendly gardening regime. Google those sites and let your plants gobble up just the right amount of nutrients they need. Make sure the fertilizer you pay for does its work in your yard and not in your neighboring lake.
Amanda McNulty is an associate extension agent for the Clemson University Cooperative Extension Service and is a co-host of “Making It Grow” broadcast weekly on ETV television stations. Website: www.clemson.edu/ extension/hgic/