As you’re probably already aware, applying lawn fertilizer is the key to getting a yard full of lush, green grass that’s hardy and resistant to yellow patches. But with so many brands and variations on the market that all promise different results, how do you know which lawn fertilizer is the best?
Lawn fertilizers come in many different forms, the main four of these being organic, inorganic, granular, and liquid. While all fertilizers work to enrich the soil with the three primary nutrients needed by plants to grow, the ratio of each nutrient present varies depending on the stage of plant growth that the fertilizer has been specially formulated for. Some fertilizers also promise extra benefits for your lawn, such as weed and insect control.
Read through this guide to understand what you should look out for when buying fertilizer for your new or existing lawn, as well as some of our recommendations on which products that we consider to be the best lawn fertilizer based on your lawn type and your desired outcomes from the fertilizer.
Understanding Fertilizer Labels
All lawn fertilizers are made up of three main ingredients: Nitrogen (N), Phosphorus (P), and Potassium (K). These three substances are known as plants’ ‘primary nutrients’, and they all play an essential role in the germination and growth of your new grass seedlings.
- Nitrogen (N) makes grass lush and green, and promotes fast growth
- Phosphorous (P) helps grass to develop strong, healthy root systems
- Potassium (K) protects grass from disease, drought, and cold temperatures
Grass plants have changing requirements of these nutrients as they progress through the stages of germination and growth, meaning that the amount of each primary nutrient present in each fertilizer varies from product to product depending on what type of fertilizer it is and what stage of growth it has been formulated for.
You can find out the quantity of each primary nutrient present in a given fertilizer by looking at the packaging and finding the NPK number. This number indicates the percentage of each of these nutrients present by weight, giving you an idea of how much of each nutrient is in the mix and in what ratio it’s present compared to the others.
To use a common all-purpose fertilizer ratio as an example, an NPK number can be 10-10-10. This means that the fertilizer is made up of 10 percent nitrogen, 10 percent phosphorus, and 10 percent potassium, with the rest of the ingredients being supplemental nutrients and filler material.
What are the Main Types of Fertilizer?
Fertilizers can come in four main types: organic, inorganic, granular, and liquid. They all contain varying amounts of nitrogen, phosphorus, and potassium, but work differently to release and supply grass with these nutrients.
- Made of naturally occurring sources of the primary nutrients
- Slow-release, gradually enriches soil with nutrients over time as the organic material breaks down
- Can be purchased or made yourself at home
- Tend to be more expensive than inorganic fertilizers
- Made of a synthesized mixture of the primary nutrients
- Quick-release, enriches soil immediately as it comes in a format that is readily taken up by plants
- Tend to be less expensive than organic fertilizers
- Made of pellets or coarse powders that can contain organic or inorganic materials
- Slow-release, gradually enriches soil over time as it breaks down with every watering
- Available in varying time-release formulas
- Gives you more control over your lawn care schedule
- Made of a liquid that can contain organic or inorganic materials
- Quick-release, enriches soil immediately as they’re designed to be taken up readily by plants
- Many types are packaged in a bottle that can be attached directly to the end of a hose for convenience when applying
What Other Types of Fertilizers are There?
In addition to enriching the soil with supplementary nutrients, fertilizers can be formulated to provide extra benefits such as weed and pest control. Some of the variations that fertilizer can come in are listed below.
Pre-emergent Weed Control Fertilizer
- Also known as ‘weed & feed’
- Feeds your lawn at the same time as working to prevent weeds
- Encourages and strengthens root system growth
- Used on already-established lawns
- Made of a nitrogen rich formula
- Revives an old lawn from dull grass to grass with a lush green colour
Moss and Fungus Control Fertilizer
- Kills moss and fungus
- Doesn’t damage grass surrounding the application area
Lawn Weed Killer
- Usually comes in liquid form, occasionally in granular
- Depending on type, can kill crabgrass, black clover, chickweed, and other unwanted growths
Lawn Insect Control
- Can be applied in the grass’ growing or dormant season
- Manages unwanted insects such as ants, ticks and fleas
- Applied using a broadcast or rotary spreader
Weed and Grass Killers
- Kills grass and weeds completely
- Used to clear areas of unwanted growth
- Usually very fast-acting
Selecting the Best Lawn Fertilizer for Your Grass Type
Before you can decide what the best lawn fertilizer is for your lawn, you need to take into consideration what type of grass you have. All grass species fall under one of two categories, being either warm-season or cool-season, so determining which of these are growing in your lawn is essential to picking the ideal fertilizer that will give you the results you’re looking for.
Warm-season grasses prefer warmer, more southern climates. They see vigorous growth throughout much of the year, therefore they require a bit more attention in their fertilization schedule than cool-season grasses do.
The most common types of warm-season grasses are:
- Carpet grass
- St. Augustine
Cool-season grasses prefer cool climates and are more often found in northern regions. They grow and thicken at a slower rate than warm-season grasses. They also require less attention to their fertilization schedule as they are usually semi-dormant during the summer months, meaning you can limit fertilizations to twice a year – once at the beginning of spring, and once again at the beginning of fall.
The most common types of cool-season grasses are:
- Kentucky Bluegrass