What You Need to Know About Home Lawn Fertilizers

Transcription

1 What You Need to Know About Home Lawn Fertilizers Another Report on Effective Turf Maintenance from the Lawn Institute A well-planned, reasonable fertility program is a basic part of proper lawn maintenance. Lawngrasses that are under-fertilized tend to be thin with poor color. Lawns that are over-fertilized, especially with high levels of soluble nitrogen fertilizer, tend to have thatch problems and are more prone to insect and disease damage. The goal of a good fertility program is to produce a reasonable amount of top growth, but not at the expense of root growth or carbohydrate storage. A good root system is the key factor to a healthy lawn. Nitrogen (N), Phosphorus (P), Potassium (K). Lawn fertilizers typically contain these three nutrients, although other nutrients may be included in small amounts. The three numbers on the fertilizer bag represent the percentages of N, P, & K-in that order. The back of the fertilizer bag should show the guaranteed analysis. Always follow the recommended application rates suggested by the manufacturer on the bag. The grass plant needs more nitrogen than any other nutrient. Nitrogen is part of the chlorophyll molecule and helps give the lawn its deep green color. Nitrogen also tends to promote high leaf growth rates at the expense of root growth. Phosphorus is responsible for the energy transfer systems in the plant and is generally required in much smaller amounts than nitrogen or potassium on an established lawn. The exception is for newly established lawns by seeding, sodding, or sprigging, when the need of phosphorus is higher in the new plant. Potassium has a lot to do with good cell wall development and the plant's ability to withstand stress, disease, and insect damage. Look for slow-release forms of nitrogen. The two basic forms of nitrogen that can be used as a fertilizer are organic and

2 inorganic. The most commonly used inorganic forms of nitrogen in fertilizers are ammonium nitrate and ammonium sulfate. Both are soluble, quickly available forms of nitrogen and both tend to produce a fast increase in leaf growth for a fairly short period of time. These are cheaper forms of nitrogen and are found in less costly fertilizers. More and more, the slowly soluble or slow-release organic forms of nitrogen are being recommended by turf experts. These include sulfur-coated urea, ureaformaldehyde, I.B.D.U., methylene urea, natural organics, and resin-coated urea. These tend to produce a lawn with good color without excessive leaf growth. They are designed to meter-out the nitrogen over a longer period of time. The slow-release forms of nitrogen are more costly than the soluble quick-release forms, but do not have to be applied as often. What fertilizer should I use? Most turf experts recommend that a lawn fertilizer should have at least one-half of its nitrogen in one of the slow-release forms mentioned above. In most cases, both cool season and warm season grasses will do well when a or ratio of N-P-K is used on an established lawn. Some analysis numbers that meet these ratios are: How much fertilizer should I use? Fertilizer application rates should be as low as possible and still produce a high quality lawn. Over-fertilization weakens your lawn and causes excess leaf growth. As a general rule, if the amount of Nitrogen (N is the first number in the analysis) is between 5 and 12, the application rate should be 8 pounds per 1,000 square feet. If the N number is between 12 and 18, the application rate should be 6 pounds per 1,000 square feet. Any N number over 19 should be applied at a rate of 4 pounds per 1,000 square feet. Always follow the recommended rate stated on the bag by the manufacturer. When should I fertilize? The best time to fertilize a lawn is when it is actively growing. For Northern lawns (cool season grasses), begin the fertilization program as the grass begins to grow in the spring and reduce applications as the weather gets hotter. When cooler weather returns in the fall, the lawn can again be fertilized. A late fall fertilizer application after the first frost can increase lawn quality the following spring. For Southern lawns (warm season grasses), the fertilization program should start just

3 after spring green-up and stop about two months before the average frost date in the fall. Frequency of fertilizer applications depends primarily on the amount and form of nitrogen used. The slow-release type fertilizers can adequately feed the lawn from 6 to 10 weeks. If the lawn still looks good and is growing well after 6 to 8 weeks, wait longer for the next application. By leaving your grass clippings on the lawn, you are adding nitrogen almost continually, which can reduce the need for fertilization by as much as 25%. And, leaving the clippings on the lawn (grasscycling) helps the environment by keeping clippings out of our community landfills! Cool Humid Cool Arid Warm Humid Warm Arid Cool Humid Transition Zone A proper mowing program goes hand-in-hand with a good fertilization program. Your fertilization program will make the grass grow! Each species of grass has an optimum cutting height to help maintain the quality of the lawn. The following table gives the suggested mowing heights and frequency for the most common grasses in North American lawns. The "rule of thumb" is not to remove more than 1/3 of the leaf surface area each time the lawn is mowed. Turfgrass Bluegrass Perennial Ryegrass Tall Fescue Fine Fescue St. Augustine Buffalograss Optimum Height Mow When It Is

4 Bermudagrass Centipede Zoysia 1.5 inches 1.5 inches 1.5 inches 2.25 inches 2.25 inches 2.25 inches Note: Based on this mowing program, there is no need to remove the clippings. The Lawn Institute 1855-A Hicks Road Rolling Meadows, IL Back to Main Brochure Page

5 Home Lawn Care Programs That Work Another Report on Effective Turf Maintenance from the Lawn Institute Having one of the best-looking and environmentally sound lawns in your neighborhood can be accomplished easier than you may think. You may still encounter some lawn "problems" during the year, but you can reduce their probability by faithfully following the lawn care programs outlined in this brochure. There are three (3) key parts to a good lawn maintenance program: Mowing Fertilizing Watering They all work together to produce a quality lawn. Leaving one part out, or not following the plan to its optimum level, will give you less than the desired results. A Mowing Program That Works Many lawn care experts believe that a majority of our lawn care problems are a result of not mowing at the proper height and not keeping our lawn mower blade sharpened throughout the mowing season. Each type of grass has its specific height for optimum performance. Mowing to keep the grass at its best growing height will increase your lawn's density and attractiveness, and reduce lawn care problems. No matter the kind of grass you have, there is a simple "rule of thumb" to follow when mowing your lawn. Never remove more than one-third (1/3) of the leaf surface each time you mow. Leaf surface, or cutting height, refers to the length of grass above the soil. Cutting below the optimum height impedes root development, which is key to having a dense, healthy lawn. Use the following chart to determine the best growing height for your kind of grass and when to mow it again. Type Of Grass Best Mowing Height Mow When It Reaches

6 Bluegrass Perennial ryegrass Tall fescue Fine fescue St. Augustine Buffalograss Bermuda 1.5 inches 2.25 inches Zoysia 1.5 inches 2.25 inches Centipede 1.5 inches 2.25 inches Note: Increase the mowing height 1/2 inch for shady areas, immediately following a drought period, or when the grass has been weakened by insect injury or high traffic. If you follow the "rule of thumb" on maintaining the optimum height and cut no more than 1/3 of the leaf surface, you can determine your cutting frequency. So much depends on weather conditions, when you've fertilized, and the amount of water the lawn has received. And remember - keep that lawn mower blade sharp! A dull blade will cause injury to the grass plant and produce stress and increase the possibility of insect and disease problems. When you use the "rule of thumb," you don't have to collect the grass clippings. They decompose quickly and put nutrients back into the soil. It's a built-in fertilization program every time you mow. No - grass clippings do not create thatch! That's an old myth! Leaving the clippings on the lawn keeps them out of the landfills and that's another environmental benefit! As a last note, there are a number of new "mulching" mowers on the market that cut the clippings into very small pieces, which allows for quicker decay. These are not absolutely necessary to a proper mowing maintenance program, but if you're in the market for a new lawn mower, you should consider a mulching mower. A Fertilization Program That Works The goal of any fertilization program is to provide the lawn with the nutrients it needs for optimum growth. The most accurate way to find out those needs is to have the soil tested. Soil test kits and instructions are usually available at lawn and garden centers, and at better hardware stores. Soil test services and information are often available through your local County Extension office. If a soil test is not conducted, follow these general fertilization guidelines. Most lawn experts agree that fertilizers with N (Nitrogen), P (Phosphorus), and K (Potassium) analysis ratios of or are acceptable for use on any lawn. Examples on the fertilizer bag that fit these ratios are: , , , ,

7 and The experts also recommend that the fertilizer should have at least one-half of its Nitrogen (N) in a slowly soluble/slow-release form, i.e. natural organics, sulfur-coated urea, resin-coated urea, ureaformaldehyde, methylene urea, or I.B.D.U. Lawns fertilized with one of these slow-release forms of nitrogen tend to have better color, thickness, and reduced leaf growth. Fertilizer application rates should be as low as possible and still produce a high quality lawn. If the amount of nitrogen (N-the first number of the analysis on the bag) is between 5 and 12, then the application rate should be 8 pounds per 1,000 square feet of lawn. If the number is between 12 and 18, the rate of application should be 6 pounds per 1,000 square feel. Anything over 19 should be applied at 4 pounds per 1,000 square feel of lawn. This is a good "rule of thumb," but always apply the fertilizer at the recommended rate listed on the bag. The best time to fertilize your lawn is when it's actively growing and in need of nutrients. For Southern lawns, this means beginning the program just after spring green-up and stopping about two months before the average frost date in the fall. For Northern lawns, begin the program as the lawn begins to grow and green-up in the spring, then reduce applications as the weather gets hotter. When the cool weather returns in the fall, the lawn can again be fertilized. A late fall application, after the first frost, has been shown to increase lawn quality the following spring. Fertilizer application dates and frequency are based primarily on which form of nitrogen the fertilizer contains. Those that have at least one-half of its nitrogen in slow-release form should be adequate for 6 to 8 weeks. If the lawn still has good color and is growing well at the end of this period, then delay the next fertilizer application a little longer. Also, if you leave your clippings on the lawn, you are fertilizing the lawn almost on a continual basis possibly extending the time period between commercially manufactured fertilizer applications. Lawn fertilization is truly the case of a little occasionally is good, but a lot at one time is bad for the grass. A Watering Program That Works The best lawns grow when they are watered heavily at infrequent intervals. On an average, the lawn needs about 1 inch of water a week, either from rain or irrigation during the growing season. This one-inch of water will normally soak the soil to a depth of 4 to 6 inches, which allows the water to reach deep into the root system. Soil types vary in the speed at which water will soak in. If you know your basic soil type, use the following table as a general guide to watering. Soil Type Infiltration Per Hour Time Required For 1 Inch To Soak In Sand 2.0 inches 0.5 hours Sandy loam 1.0 inches 1.0 hours

8 Loam 0.5 inches 2.0 hours Silt loam 0.4 inches 2.25 hours Clay loam hours Clay hours You must determine the rate of application of your sprinkler system to set up any irrigation program. An easy way to do this is to set out a series of straight-sided, flat-bottom cans if you have an underground sprinkler system or a couple of cans if you use a single sprinkler. Run the system 30 minutes and measure the water in the cans. With a little simple math, you can determine the length of time to apply one inch of water. Watch for runoff during the watering period. It is very possible that your lawn will not be able to soak up the water as fast as your sprinkler is putting it on the lawn. If this occurs, shut it off and wait on-half hour, then turn it on again. Also, remember that sloped areas will have more tendency for runoff. The best times to water your lawn are in the early morning or early evening when there is generally less wind and heat. The lease desirable times are in the heat of the afternoon, when water evaporates too quickly, and very late in the evening, which can cause the lawn to stay wet all night. This encourages disease development. Over-watering is much worse than under-watering. Most grasses can live through reasonably long periods of drought. Water only when the soil is dry 4 to 6 inches below the surface. Use a screwdriver or other probe to determine dryness. Also, if the grass doesn't spring back up after walking on it it's probably time to put another inch of water on the lawn. The Lawn Institute 1855-A Hicks Road Rolling Meadows, IL Back to Main Brochure Page