Is fertilizer a good feast for your lawn? Yes and no. Just like with our own food intake, too much, too little, the wrong combination of stuff, quality and timing all affect how healthy we are, so it goes with fertilizing our lawns. Let’s look at a few basic things to consider as you decide when and how you’ll feed your hungry lawn this season.
What is Fertilizer?
It helps to clarify that, technically, fertilizer isn’t actually “food” for your grass. If you remember from biology class in school, plants use the photosynthesis process to make their own food with a combination of sunlight, air and water. That’s the work that goes on primarily above the ground in the leaves. Underneath the ground, the soil provides nutrients and minerals to the root system, but often the soil gets depleted or needs supplements. So maybe that’s a good way to look at fertilizer – more like taking vitamins and mineral supplements. However, these elements are vital for the plants to grow so in that way, fertilizer is like food.
Essential Ingredients – The 17 essential elements that plants and lawns need are divided into two categories: macro- and micro-nutrients. Three of the elements (carbon, hydrogen and oxygen) are taken from air and water. Fertilizer can provide many of the remaining must-have elements that roots utilize from the soil.
The three primary ingredients of fertilizer are nitrogen (N), phosphorus (P) and potassium/potash (K). On every bag of fertilizer you’ll see those initials in that order – NPK – and numbers associated with it. This is how the industry communicates what percentage by weight of each ingredient is in what you buy. The numbers are not a ratio and are not how many pounds of that ingredient are in the bag. It is percentage by weight: if the bag weighs 25 lbs and first number on the bag (N) is 10, then the bag contains 2.5lbs of Nitrogen (not 10 lbs).
The micro-nutrients are often called “trace elements” and every fertilizer varies in what micro-nutrients are included. Check the ingredients for these, such as calcium, magnesium, sulfur, iron, chlorine, copper, manganese, zinc, molybdenum, and boron.
Types and Options – There are two types of fertilizer available: organic and commercial.
Organic fertilizers come in options that are naturally-occurring (manure, worm castings and pea) or processed (compost, blood meal, bone meal).
Commercial fertilizers come in organic or inorganic material of natural or synthetic origin (lime, gypsum, manipulated animal and vegetable manures).
Biofertilizers (Phospho, Rhizo, Vermi compost) are also an emerging, new product to consider.
Be aware of the impact of your decision about which one to use. Some states have banned the use of phosphorus (P) and limited nitrogen (N) because of environmental concerns. Yet organic fertilizers are harder to measure and balance what nutrients you’re adding. Don’t take the decision about which one to choose lightly – do your research and weigh the pros and cons.
Because your soil needs it - Before fertilizing, it is important to know your soil composition so that you aren’t adding chemicals unnecessarily. Test your soil so you know what you’re working with.
To offer a “balanced diet” – Your soil test will show what nutrients are lacking and fertilizer is one way you can put them back in.
For a green lawn – Yellowing, slow-growing lawns may benefit from more nitrogen, which helps lawns be green and grow fast. Nitrogen is the only nutrient that turf grass needs regularly. However, if you apply it too often, the root growth will be inhibited which will lead to other problems.
To promote grass root growth – Slow-release fertilizers do the best job of helping roots grow. Slow release fertilizers release nutrients gradually while fast release fertilizers make them available all at once. Fast release fertilizers can be cheaper, but in general they are not the best option for long-term benefit because they require more water to prevent burning, and a lot of the mineral content can be lost and not utilized by the roots. If you concentrate on building a good root system for you lawn’s grass roots, you will not need to fertilize as frequently. This includes practices such as optimal mowing height (longer than you’d expect), good irrigation (water deep, not frequent and shallow), maintain correct soil pH.
To help young grass get started – New grass seeds require a different combination of NPK than established lawns, so be sure to purchase “starter” fertilizer, or organic, slow-release fertilizer. Avoid fertilizers with weed preventer in them.
When to Fertilize?
Fertilizing at the right time is critical to lawn growth and health, as well as to being environmentally responsible. If your soil testing shows fertilizing is needed, the decision about when is dependent on what kind of grass you grow. In general, cold season grasses (Kentucky bluegrass, fescues) need to be fertilized in the fall and energy stored in the roots over winter will provide everything grass needs for spring. Warm season grasses (Zoysia, Bermuda) need to be fertilized before spring rains.
How to Fertilize?
The key is even application. Never apply fertilizer by hand. It will distribute unevenly and it will be obvious soon after because your lawn will be greener in some spots and may burn in others.
For dry fertilizer, use a hand-held or push-type distributor that is designed to apply fertilizer evenly and in specified amounts. Check the bag for instructions about how much you need and do not over apply. Too much fertilizer is not a good thing. Be intentional about your pattern, starting at the ends or edges of the lawn and making your way in. Walk at a normal walking pace and try to keep the same rhythm throughout.
Liquid fertilizers can be applied with water hose applicator. Start at one corner of the lawn and walk backwards as you spray in smooth, even strokes.
When finished, be sure to clean out your applicator and wipe up any overspray or excess.
Well there won’t be any test for you to take over this “Fertilizer 101” material, but the true test will come when you see the results on your greener, better-growing lawn soon!