A healthy lawn is less likely to be invaded by pests — both weeds and insects. Getting on the right fertilizing schedule can help keep the weeds out of your yard while keeping your turf lush and green. At the same time, over-fertilizing your lawn can cause severe problems to your grass and the environment.
A fertilizer is any product that contains at least one of the nutrients needed for plant growth. The most common of these for lawns are nitrogen, phosphorous, potassium and iron. Your turfgrass gets most of these naturally from either the soil, air or water supply, but sometimes one or more of these nutrients are in low supply. On every package of fertilizer there is an N-P-K rating, or the three numbers representing the amount of nitrogen, phosphorous and potassium. Fast-release fertilizers give a quick response in greening up your lawn, but they are also more prone to burning your lawn and you need more applications throughout the season. Natural fertilizers don’t typically burn, but they are bulky and have lower amounts of nutrients. Slow-release formulas are often the best when it comes to long-term results because they allow the nutrients to be released over time.
In general, applying lawn fertilizer is best done near the beginning of the growing season, or mid-spring. May and June are good months for this first application. You should also apply in early fall, in September or October. When applying fertilizers, your lawn should be clear of any heat or cold stresses such as heavy frosts or the hot afternoon sun of midsummer. Of course there are exceptions to this general rule. Different areas and grass species require different applications.
In many cases a thorough look at your lawn can help you decide if you need to apply fertilizer. Lawns suffering from nitrogen deficiencies will have a yellow-green to yellow color, stunted growth and weeds — particularly clovers. You’ll probably also notice a great reduction in grass clippings when you mow your lawn. Iron deficiencies also leave your lawn a yellowish color, but there is no obvious stunting. Phosphorous deficiencies leave your turf a bluish-green color, with some blades turning purple or reddish. The second option for determining deficiencies is to have your soil tested by a lab. You can order these tests online, through some nurseries or you can contact your local university extension office for more information.
Fertilizers and herbicides help your lawn to be lush, green and weed-free. Not all of these products are created equally, so the timing and frequency of application varies from product to product. Sometimes knowing when to apply these products is as simple as looking at your lawn for signs and symptoms of deficiencies or problems.
Like fertilizers, not all weed killers are created equal. Pre-emergent herbicides kill the weeds before they emerge from the ground and as such should be applied early in the season before these weeds take over. Post-emergent herbicides kill the weeds once they have come up and should be applied when you see the weeds.
With a professional background in gardening, landscapes, pests and natural ecosystems, Jasey Kelly has been sharing her knowledge through writing since 2009 and has served as an expert writer in these fields. Kelly's background also includes childcare, and animal rescue and care.
The label on a bag of lawn fertilizer will recommend a schedule based on the type of fertilizer it contains. The label is your best guide to how often to apply the product and how much to use. As long as you don’t overdo it and avoid fertilizing in the hottest part of summer, your lawn should thrive.
Organic materials such as compost and manure – The essential nutrients aren’t as concentrated in these types of materials, so you have to use a lot. Compost or dry manure before applying it to the lawn, and be aware that some manures, particularly horse manure, may contain weed seeds.
When to Put Fertilizer on Lawns
Fast-release – You get quick results with a fast-release fertilizer, but you have to apply them in smaller amounts and more frequently. You can burn your lawn with a fast-release fertilizer if you use too much.
Weed and feed – Try to identify your weeds before using a weed and feed product and make sure your weed is listed on the product label. Take special care around trees, shrubs, and garden plants.
There are several ways to apply lawn fertilizer. Using a spreader provides more even coverage than fertilizing by hand. Hand fertilizing often results in burns where the fertilizer is concentrated and pale areas that don’t get as much fertilizer as they should.