Fertilizers contain the three main nutrients necessary for growth: Nitrogen for leaf growth, phosphorus for root growth and seed formation and potassium to maintain overall vitality. There are two basic kinds of fertilizer: natural or manufactured. Natural fertilizer can be a variety of substances ranging from manure to decomposed plant matter from grass clippings while manufactured fertilizer is comprised of minerals or synthetics produced in factories.
Lawn fertilizers are applied one of two ways, by broadcasting dry fertilizers or by spraying liquid types. Most dry fertilizers are water soluble and enter the soil over longer periods of time. The impact of liquid fertilizers is felt almost immediately but their results are shorter lived.
Here are a few tips for applying fertilizer:
- Amounts: Most lawns require somewhere between four and six applications of fertilizer annually, depending on the fertilizer, grass type and soil. Cool-season grasses generally require a minimum of four applications; Warm-season grasses usually require monthly applications to sustain growth.
- Timing: While the conventional wisdom is that spring fertilizing gives your lawns a head start on growth, it’s really the fall fertilizing that is more important. Warm-season grasses need one last application to carry their color and growth throughout the fall. Cool-season grasses rely on this application to develop root systems and store nutrients for growing season ahead.
- Weed control opportunities. Fertilizing provides an opportunity to apply some weed control. In the spring, fertilizers can be joined with pre-emergent herbicides to kill weed seedlings. In the summer, when combined with a post-emergent herbicide, fertilizing can keep weeds under control.
- Know your numbers. Three prominent numbers on a fertilizer bag (e.g., 10-10-10 or 20-10-5) represent the amount in percentage by weight of the three primary nutrients nitrogen, phosphorus, and potassium. A soil test can determine the amount of phosphorus and potassium your lawn needs. Nitrogen levels are not determined by soil tests as they fluctuate rapidly in the soil to have any practical meaning.
If this all sounds reminiscent of a high school science class, there’s good reason. Lawn care does involve science. There is no cookie-cutter approach to a healthy lawn and there shouldn’t be too much guess work in figuring out what your lawn needs. To ensure your landscape gets the right care to ensure its maximum health, consult a trained lawn care expert who can determine what formulation is best suited for your lawn and soil conditions.