We fertilize to replace nutrients lost to plant growth and leaching, to increase leaf and root growth and to aid in recovery from pest damage and environmental stress.
Storm water from heavy rain takes plant nutrients with it as it flows off lawns and gardens into our ponds and waterways. The lost nutrients need to be replenished.
Three bold numbers are printed on fertilizer packaging. The numbers refer to the three basic elements, called macronutrients, your lawn and garden plants need in large quantities to survive: (N) nitrogen, (P) phosphorous and (K) potassium, in that order.
Nitrogen is vital to leafy green top growth. Plants consume large amounts of nitrogen as they leaf out in the spring. Nitrogen aids in the production of chlorophyll, which promotes faster development of foliage.
Phosphorous supports root development. It promotes flowering and increases bloom size. You will find that high phosphorous fertilizers are often marketed as bloom boosters.
Potassium serves a number of functions that support overall plant health. It improves root development. It builds disease resistance as well as drought and cold tolerance.
A “complete” fertilizer is one that contains all three macronutrients — nitrogen, phosphorous and potassium. A fertilizer is identified as “incomplete” when it contains only one or two of the three macronutrients. Don’t be misled when a fertilizer is marked “complete.” It means that the fertilizer contains all three macronutrients, not the additional elements that plants need.
Calcium, magnesium and sulfur are secondary elements, which must be supplied when inadequate in the soil. Micronutrients — zinc, manganese, iron, boron, copper, molybdenum and chlorine — are also important for plant health, only they are required in small amounts.
Most annuals have been raised on a constant diet of liquid chemical fertilizer. They will get through their short lifespan quite nicely with weekly or bi-weekly liquid fertilizer or slow-release granules.
Ornamentals are well-served with a spring helping of compost and slow-release fertilizer.
Grass that has fully greened up is ready for fertilizer. Proper moisture is important. After heavy rainfall, the water in the soil provides for good distribution of fertilizer. Light watering, a quarter-inch or so of irrigation or light rain, will wash granules off leaves and take them down to the root zone where they benefit the grass. Use a slow-release product that feeds turf over a long period of time. Don’t apply fertilizer if heavy rain, a storm or flood is predicted in the next 24 to 36 hours.
Note to lawn-loving readers who insist upon fertilizing before grass fully greens up: Be aware that quick top growth can result in weak grass that is less disease- and pest-resistant.
Avoid using weed and feed products on your lawn. Herbicidal chemicals in “weed and feed” can damage groundcover, vines, shrubs and trees whose roots extend into the lawn area.
There are various ways to provide nutrients to your plants — dry, liquid, organic, chemical, slow release, etc.
Chemical fertilizers are appealing because they can be relatively inexpensive and require the application of less product material than organic fertilizers. Nutrients from chemical fertilizers that dissolve in water become available to plants quickly. Some controlled-release fertilizers now contain micronutrients. Look for fertilizers labeled “plus” or “total.” Palm fertilizers, in particular, contain specific nutrients palms need.
Organic fertilizers are many times a good source for micronutrients. Typically kelp, seaweed and fish emulsion are high in micronutrients. Organic soil amendments do more than deliver a slow release of nutrients; they also improve the soil for future growing. It is something to consider when you choose how you will fertilize your plants.
Reach DEBBIE MENCHEK, a Clemson Master Gardener, at firstname.lastname@example.org.