Spring is a good time to make sure your lawn and plants contain the proper nutrients to thrive through the hot summer months. LawnCare.net recommends not fertilizing in the early spring. Fertilizing too soon could promote top growth and weaken the root system, which may not be able to handle the hot and dry summer weather.
When it comes to fertilizing your lawn, the amount of fertilizer depends on the type of grass and the region's conditions. Although each grass species may need a different fertilizing schedule, the necessary amount is "1 pound of actual nitrogen per 1,000 square feet per application," according to Jeff Rugg, a horticulture educator at the University of Illinois Extension and writer of the syndicated column "A Greener View."
By providing the needed nutrients, fertilizer acts as a tool to sustain plant health, according to Scott Aker, the gardens unit leader at the U.S. National Arboretum, in Washington, D.C. Nitrogen, phosphorus and potassium are fertilizer's main components. A soil test can help determine whether there are insufficient amounts of these three elements. Rugg suggests contacting your local soil testing company for an examination.
The type of fertilizer depends on what plant needs to be treated. Both liquid and dry fertilizers can supply fast or controlled releases of nutrients. Chemical fertilizers provide fast releases of balanced levels of nitrogen, phosphorus and potassium, whereas organic fertilizers usually put the nutrients into the soil at slower rates. Be careful not to overuse chemical fertilizers on your lawn; the chemicals can cause groundwater pollution, and their high salt levels can burn the grass, according to LawnCare.net. Some organic types contain lower amounts of nitrogen, so if you use them, you need more fertilizer to spread across the lawn, according to a lawn care article from the University of Illinois Extension. Although organic fertilizer works at a slower pace, Aker says it could offer a more balanced nutrient release over a longer time period.
"The best type (of fertilizer) feeds the lawn without feeding anything else by washing into ponds and streams," Rugg says. "It should never contain weedkillers or insect killers, unless that specific problem has been diagnosed at that particular time."
Certain plants or shrubs could require greater amounts of fertilizer. For example, Aker says flowers need more fertilizer than ground cover. And planting areas with shortages of soil, such as container gardens, usually require more fertilizer to make up for the lack of nutrients. Liquid fertilizers are easier to use when treating container gardens. If the soil contains enough organic material, nutrients and water, plants don't require additional fertilizer.
Mulch protects the soil and roots, whereas fertilizer's main duty is to provide nutrients for plants. Mulch stops weed development and aids in preserving soil moisture and maintaining moderate soil temperatures, according to Aker. And Aker says that mulch "serves an aesthetic function by eliminating the splash of dirt onto plants and giving beds a neat, finished appearance."
There are organic and inorganic mulch products. Rugg recommends organic mulch for most plants; it delays putting nutrients back into the soil, similar to a slow-release fertilizer. Inorganic mulch contains gravel or shredded rubber material.
"Mulch is a bunch of material sitting on the soil surface that insulates the surface from quickly freezing and thawing," Rugg says. "And it helps prevent the soil underneath from drying out too fast."
Be careful not to go overboard when using fertilizer; too much can harm plants and the environment. Only use fertilizer if you know it is needed in your yard. Mulch that's deeper than 2 inches will damage plants, as well, according to Aker. Usually, warmer and wetter weather means a greater loss of nutrients; rain may filter out nutrients, and hot soil temperatures can reduce nutrients through volatilization.
"Plants need nutrients when they are actively growing," Rugg says. "A longer growing season means plants need more nutrients."