Learn about Lawns How to Fertilize Your Lawn

Why do you need to fertilize?

Your lawn takes nutrients out of the soil and uses them to aid growth. If your soil lacks adequate nutrients your lawn will suffer. First, as you probably know, fertilizing makes your lawn greener. Most people fertilize to green up the lawn but they don't know much more than that about why to fertilize.

Fertilizers can include chemicals to inhibit or kill weeds. However, a healthy lawn can actually can keep weeds at bay on its own. A healthy lawn competes with weeds to grow and will win when it has the right conditions.

Another reason to fertilize is that when the nutrients are available, the lawn develops healthier roots. Healthy roots grow deeper. Deep roots can better draw upon water and nutrients in the soil. Furthermore, deep roots reduce thatch and browning. Finally, fertilizer contains nutrients that grass needs to resist disease and drought.

Why are there so many different fertilizers?

The three primary nutrients in a fertilizer are Nitrogen, Phosphorous and Potassium. Each element has its own affect upon grass. Nitrogen stimulates grass growth and greening. Phosphorous stimulates the development of roots and seedlings. Potassium promotes disease and drought resistance.

As the weather changes, your lawn has changing needs. In the heat of the summer, your lawn needs water and little else. In order to survive the cold weather, your lawn needs to have healthy roots and so a fertilizer to promote root growth should be applied before the cold weather sets in. At other times of year your lawn needs nutrients to enable growth and greening. Finally, various weeds have their own growing seasons. In order to give your lawn the edge over weeds, you should fertilize at the beginning of the various weed growth seasons.

Where you live, the type of grass you have, the condition of your soil and the weather all affect your choice of fertilizer and when it should be applied. You also have a choice of organic fertilizer, liquid fertilizer, which is sprayed on, or time released granules which are distributed with a spreader. All of these factors result in the many choices of fertilizer.

What do those numbers on the package mean?

Fertilizer is comprised of three primary nutrients; Nitrogen, Phosphorous and Potassium. The symbols for these nutrients, respectively, are N - P - K. The numbers on fertilizer packages represent the ratio of the nutrient to the total weight of the package. So a 50 lb. bag labeled as 25-5-10 is 25% nitrogen, 5% phosphorous, 10% potassium. By multiplying the weight of the package, by the percentage of the nutrient, you can determine the number of pounds of each nutrient. So in the example above, .25 * 50 lbs = 12.5 lbs. of nitrogen, 2.5 lbs. phosphorous and 5 lbs. potassium.

So what is the rest of the bag contain? Mostly inert fillers. Why not make the bay lighter and leave those fillers out? Those fillers help with even distribution of the nutrients and in the slow-release of nutrients over time.

When should you fertilize?

The weather is the chief influence on when to apply nutrients. The beginning and end of the growing season are the two most important times to fertilize the lawn. These two applications will be adequate to sustain a healthy lawn. However, also preparing for the winter and fertilizing prior to the appearance of weeds will give you the best results.

Where you live influences the timing for each of these applications. If you live in a warmer climate, then the early and late summer are ideal for pre and post growth season applications. In colder climates, spring and fall are the best times to apply nutrients. Early summer is the time to apply nutrients to aid in the prevention of weeds.

For winter protection you should apply fertilizer prior to the first frost or in warmer climates, when the grass stops growing.

Which fertilizer should you use?

You should have your soil tested every 3-4 years to determine what nutrients may be needed. You can purchase a soil test kit, or take a sample to a local nursery. Some counties have agencies that can also test soil for a nominal fee.

The result of your soil test will be a factor in your choice of fertilizer. Generally, the proper ratio of primary nutrients (nitrogen, phosphorous and Potassium.) is influenced by the season. The selection of secondary nutrients is influenced by the condition of your soil.

You have three choices when it comes to form of fertilizer; organic, liquid or timed release. Organic fertilizer is your classic food or animal waste that has been composted. The benefit of organics is that you really can't damage your lawn by over-fertilizing. You may also have a ready supply of composted material. The down side is that it won't contain the balance that your lawn needs, it is heavy, requires large quantities and is relatively difficult to apply. Liquid fertilizer can be convenient to apply because it is sprayed, usually with an attachment to your hose. However, it doesn't last as long and so it must be applied much more often. Slow release fertilizer comes in granules which are spread with a hand spreader or larger push spreader.

Also, don't underestimate the value of leaving the lawn clippings when you mow. These clippings break down quickly and return vital nutrients to the soil. The rumors you have heard about lawn clippings leading to thatch are untrue. The USDA has tested and determined that thatch does not result from lawn clippings being left on the lawn. The key is that you don't wait until the lawn is too tall and that you mow only when the grass is dry. Otherwise, you will end up with clumps of clippings that turn brown and are unsightly as well as may block sunlight from the grass underneath.

Because of all the factors that influence the selection of fertilizer, you should take advantage of the knowledge of the staff at your local nursery or home center. First of all, they are generally going to stock the appropriate fertilizer for the current season and the unique considerations for your region. Furthermore, their staff can help you to identify your variety of grass (bring a sample with you), answer your questions and help you select the appropriate fertilizer for your needs.

How much Fertilizer should you use?

Over fertilizing can lead to chemical burn, excessive top growth and weakens your lawn. Under fertilizing results in a lawn that lacks color & lushness, increases risk of disease and results in more weed growth. Clearly, getting the right balance is important.

This is also where the local nursery staff is invaluable. The type of grass will affect the quantity of nutrients needed. Ask the staff to help you select the right product for your type of grass (remember, bring a sample of your grass). If you know your variety of grass, you can also just read the packages as they will include detail of how much of their product to use for your variety of grass.

Always follow all of the directions for the use, application and cautions listed on the package. Use of protective clothing, gloves, eyewear and breathing masks is recommended when working with chemical fertilizers.