Lawn fertilization can be tricky business, but if you want your lawn to look vibrantly green there really isn’t any other option. Unfertilized lawns tend to look stressed, show signs of thinning, are more susceptible to disease, and can become overrun with weeds. It’s super easy to make mistakes fertilizing your lawn, so we’re here to help you navigate the in-and-outs of lawn fertilization. Homes with beautiful lawns are an important factor in having a happy and healthy neighborhood. It helps keep people happy and it adds value to home values. Unfortunately, lawn fertilization is poorly understood by the vast number of people. Apply too much fertilizer and you can burn out a lawn. Apply fertilizer too close to water runoff and you can end up with algae blooms in ponds and lakes. Applying too much fertilizer can also cause it to seep into groundwater. Obviously, none of these situations are ideal and getting some research under your belt probably isn’t a bad idea.
Lawns are plants that uses at least sixteen different nutrients from the soil in order to grow into a medium to dark green shade that is thick and resilient. When it comes right down to it, proper fertilization techniques will give you the most bang for your buck in terms of maintaining a quality lawn. Homeowners need to know how to apply fertilizer, when to apply it, and how much to put out. They will also have to buy a spreader that they should wash out after every use.
It’s Just Science
Fertilizing is crucial for a healthy lawn. However, it is crucial to fertilize correctly. While turf requires sixteen different nutrients to thrive, it needs these in varying proportions. Throwing off the balance, even just slightly, can result in grass that is dried out, yellow, or sparse.
Of the sixteen nutrients required for successful turf growth, nine of them are necessary in larger quantities and are known as macronutrients: carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur. The first three makeup as much as 95% of the composition of each blade of grass and are never deficient as they are derived from carbon dioxide and water.
The next three nutrients are considered primary nutrients. Nitrogen, phosphorus, and potassium do need to be replenished in turf periodically throughout the growing season. The last three nutrients are only necessary once in a while and can be applied either as fertilizer or lime.
The remaining seven nutrients required for growing healthy grass are called micronutrients. These include copper, manganese, iron, zinc, boron, chlorine, and molybdenum and are only needed in tiny amounts and rarely supplied during fertilization. Iron can sometimes be used on grass to encourage a darker green without promoting additional growth.
Each nutrient has a specific role in producing healthy and beautiful lawns. Nitrogen and phosphorus are required for many of the plant’s normal functions, whereas many of the rest are only responsible for inducing a few chemical reactions. In plain English, nitrogen and phosphorus are among the most crucial ingredients required for healthy turf.
Key Do-it-Yourself Considerations
When fertilizing a lawn there are several things to take into consideration. The first thing you want to do is determine your grass type. Once this is done, you will then want to research the amount of fertilizer to put on your lawn using official resources, and then select from available options at the local hardware store or nursery. Every state is different and there are dozens of sub-varieties of major grass types that require different amounts of fertilizer. You will also want to consider weather conditions we discuss later in this article.
Reading Fertilizer Labels – NPK’s
Fertilizer manufacturers are required to list what are known as “NPK’s” to give consumers a key reference point informing them of the Nitrogen, Phosphate, and Potassium levels in the fertilizer being purchased. A 24-12-12 NPK would indicate that the fertilizer contains 24% nitrogen (N), 12% phosphate (P2O5) and 12% potassium (k2O). A 20 pound bag of fertilizer with these nutrient levels would contain 4.8 lbs of nitrogen (N), 2.4 lbs of phosphate (P2O5), and 2.4 lbs of potassium (k2O). Fertilizers are often used in ratios using these numbers. A 24-12-12 NPK would have a 2-1-1 fertilizer ratio.
Fertilizer Apps: When, Where, and How
Knowing when to fertilize your yard is half the battle. Applying too much fertilizer will result in burning your grass and potentially contaminating water sources. Not using enough fertilizer will do little to encourage proper growth and nutrient uptake and will waste time and money. Applying the wrong fertilizers can result in any number of issues with your turf.
For the most part, you want to begin the season with fertilizing your lawn in late spring or early summer using a granular fertilizer with a broadcast or rotary spreader. These can help more evenly distribute the granular fertilizers throughout your lawn for slow-release fertilization throughout much of the growing season. A day or two before fertilizing, water your lawn. When spreading fertilizer, start at the perimeter of your lawn and then move back and forth over the area of your yard with only a slight overlap to ensure even coverage. Lightly water your lawn after fertilizing to help activate granular fertilizers and washes granules off the blades of grass and into the soil. You will want to fertilize again in late summer in warmer climates. In climates where grass goes dormant in the winter, don’t apply your second fertilization until early fall.
Minerals and nutrients must be in certain forms to be of value to your lawn. For example, there is a significant amount of nitrogen found in the atmosphere. However, this form of nitrogen does little to benefit grass. Nitrates or ammonia, however, are nitrogen compounds found in the soil that is the crucial compound necessary for grass to be able to photosynthesize. They are in a soluble form, which is then taken into the plant’s root systems through water and allow it to turn the desired deep green we expect from healthy lawns. At times, microorganisms in the soil can take up a good portion of the available nitrates or ammonia in the soil before the grass can absorb it.
Granular fertilizers are typically longer-acting. While the nitrogen and other nutrients are present in granular fertilizers, they are designed to break down over time as moisture is introduced to the particles of fertilizer wither through watering, the rain, or morning dew. Granular fertilizers are excellent for long-term nutrient replenishment to help feed your lawn. They are also less likely to burn your grass than liquid fertilizers. Granular fertilizers are often more expensive than liquid fertilizers as well, though they will typically last longer than liquid applications. This type of fertilizer is often part of a good grass fertility program to keep your lawn looking its best all season long.
These fertilizers are applied directly to turf in liquid form. There are several benefits to liquid fertilizers, but one of the most important is that it is fast-acting. Liquid fertilizers are already water-soluble, so they can immediately be absorbed into the plant’s root system and into your grass for an almost immediate result. Liquid fertilizer applications are also typically less expensive. The downside to liquid applications is that there is a greater potential for burning your grass. It is also not as long-lasting, which means you will need more frequent applications throughout the growing season.
Bio-Nutrient Based Fertilizers
Bio-Nutrient fertilizers are becoming more in demand in recent years as people want to decrease the use of chemicals. Bio-nutrient fertilizers work by helping to foster nitrogen fixation naturally without adding additional chemicals to lawns. These are typically considered a safer alternative than the other types of fertilizers and are touted as kid and pet-friendly options. Bio-fertilizers are usually composed of living organisms, and work within the soil and root systems of grass to help improve nutrient uptake as well as create ideal soil conditions for a healthy lawn. The downside of bio-nutrient based fertilizers is that they typically take longer to work.
Fertilizing Newly Planted Turf
A common issue you see is over-zealous homeowners and property managers over-fertilizing newly laid sod or grass seed. They are usually a combination of wanting their grass to be green, as well as being desperate for their investment live and not get killed off accidentally, which would require re-planting.
Overall, people just need to calm down and fertilize modestly! Too much fertilizer can burn out newly laid sod or grass seed if it isn’t watered properly. On top of that, you want to be encouraging root growth. You want the roots of your newly planted lawn to be in a growth mode where the roots are actively spreading deeper into the soil seeking out nutrients and moisture. If your grass roots can just sit in a puddle sucking up excessive nitrogen, those kind of conditions can actually inhibit root growth. Lastly, fertilizer applied to newly laid sod or grass seed is more likely to run-off into ground water or waterways than an established lawn. So keep things modest and your lawn will spread and grow like you want it!
What is Urea?
Urea is just a relatively inexpensive fertilizer consisting of nitrogen and filler. The NPK ratio for urea is 46-0-0. Urea is a common fertilizer used by professional lawn care services who mix urea with water and deploy it via a spray application that can sometimes include weed control products.
What is Milorganite?
Milorganite is a slow-release granular fertilizer that consists of biological compounds filtered through the Milwaukee Metropolitan Sewage District. Milorganite refers to “Milwaukee Oragnic Fertilizer”. Milorganite is often used by professional lawn care companies in the summer during times of high heat or when there is little moisture in the environment, as it is considered less likely to burn out lawns than most other forms of fertilizer that contain nitrogen.
Water Your Fertilizer In!
Modestly watering recently spread fertilizer into your soil after it is applied is almost always good advice in our opinion. This enables two things primarily. First, this will allow the water to wash off the grass blades so the fertilizer molecules will runoff into the top inch of soil where it can be absorbed by the roots of the grass. A quick 5 minute watering will usually get the job done. Secondly, lawns love water. So a little water combined with some recently applied fertilizer is a proven recipe to brighten up your lawn quickly so that it is vibrantly green.
Be cautious though. Over-watering can cause too much runoff that is bad for the ecosystem. You want the fertilizer to stay in the top 1 inch of soil so it’s available for your lawn to take up. If you water for 30-45+ minutes there is a good chance you can cause the fertilizer to seep too far into the soil that can sometime jeopardize groundwater supplies. Water can also start to runoff and pull fertilizer into water ways, rivers, or streams. None of this is desirable, which is why we usually only recommend a quick 5 minute watering after fertilizer is applied, and up to 20 minutes of watering during routine lawn watering.
Regular Watering and Weather Conditions
Fertilizing a lawn provides very little benefit if the roots and grass blades don’t have access to the moisture it needs in order for biochemical processes to operate smoothly. As mentioned above, we think that it’s important to water fertilizer in modestly for around 5 minutes after it’s applied. Long term, homeowners and property managers, who want a vibrantly green lawn, should manage their turf so that they maintain moisture in the top inch of soil. This is accomplished through regular watering during the growing season. We usually recommend 20 minutes of watering, 4-5 times a week. The number of times watering is need is ultimately dependent on how much rain your lawn has received. If you are dealing with scorching heat feel free to water almost every day. Also take into consideration the wind. Consistent winds, even modest wind, can strip the moisture out of topsoil. These conditions usually present with periods of high heat. So, just keep an eye on the moisture levels in the top inch of topsoil. If there isn’t moisture, water during the growing season!
Warning About Salts / Fillers in Fertilizer
Everyone’s heard about how fertilizer can burn up a lawn, but few people know why this actually happens. What is happening here is that recently applied fertilizer contains salts/similar compounds that actually soak up water molecules. So, when fertilizer is applied to a lawn, especially liquid applications that coat grass blades, the fertilizer itself sort of acts like a sponge, sucking water molecules out of the grass blades, which then cause biochemical disruption within the grass. This is one of the reasons that can cause a lawn to “burn up”. This is one of the reason why we recommend that fertilizer applications be watered in modestly after they are applied. It helps offset this phenomena.
Shaded vs Non-Shaded Lawns
The thing to keep in mind is that shaded lawns usually require less fertilizer than non-shaded lawns. This usually doesn’t stop homeowners or lawn care services from deploying pretty much the same amount of fertilizer on shaded vs non-shaded parts of lawns, but it is something people should think about. Homeowners with shaded lawns can save money by fertilizing less often. Lawns that are shaded also have less of a need to be watered, which can also save money. Of course we live in the real world where most lawns are partly shaded and partly have exposure to near full-sun.
Grass Cycling – Leave Behind Clippings
Grass cycling is the process of leaving behind lawn clippings when the lawn is mowed in order to utilize the nutrients in the clippings to feed your turf as well as the microorganisms and insects that live in the area. We believe grass cycling is a reasonable way to help fertilize your lawn naturally but the process does not come without issues. The first issue is safety. When homeowners or lawn mowing services “mulch” their lawns, mower decks are much more likely to get clogged up and overrun with clippings. This can put the person mowing the lawn in a constant state of having to clear the deck, which can be dangerous when it has to be done over and over again. Lawn mowers that throw off clippings, instead of mulching, pose a different risk because the lawn mower operator has to deal with objects being blown out of the mower at very high speeds. This can damage homes, fences, cars, and is dangerous to other people located in the immediate area. Another issue is too many lawn clippings can cause thatch on the lawn that can actually end up suffocating the turf and can hurt it’s ability to drain. Lastly, clippings can become a breeding grounds for insects, which is not ideal if you have pets or children.
Healthy Soil Goals
Having healthy soil is critical to the success of your turf. Soil that is dense and compact will often lack the available nutrients for grass to thrive as well as make it more difficult for roots to grow deep into the ground. Deeper roots encourage a more resilient lawn that is drought resistant and long-lasting. Sand, silt, and clay are three core components of great soil, sometimes referred to as loam soil. This makeup helps with airflow, water flow, drainage, and fertilization.
Hiring a Lawn Service
To truly provide the best possible care for your lawn, hiring a lawn care service that can control weeds and manage fertilizer applications can be your absolute best bet. Professional lawn care companies will typically use a combination of granular, liquid, and bio-nutrient fertilization techniques to help keep your yard looking like a professional golf course or baseball field. They know the best methods for treating lawns as well as how to mitigate common problems with lawn care and maintenance. Professional lawn care companies can save a significant amount of time and money and can get you on your way to having a picture-perfect yard all summer long.