A lot of homeowners decide not to bother with fertilizing their lawn as they are unsure how to best apply it.
Some have seen reports of burnt lawns from too much nitrogen and want to stick to simple watering. That may not be enough to keep the grass healthy and if you want to treat your lawn with fertilizer then you should know how much to use.
Lawn fertilizer can be expensive so knowing how much to apply to your lawn means getting the best out of your buck.
There are certain methods to determine how much fertilizer you should use yet that can depend on various factors.
Put bluntly, the amount of fertilizer you require for your lawn will depend on its size and how much nitrogen the grass requires.
An excessive amount of fertilizer can be harmful to your lawn whereas too little can be wholly ineffective. There are some calculations and measurements to be made and then you should know how much fertilizer to use on your lawn.
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Measure Your Lawn
When measuring your lawn, remember that you do not need an exact measurement.
You could use Google Earth to find your address and then use the ‘Measure distance and area’ tool. Highlight the starting point on the map then select each corner until you have covered your lawn to determine the total area.
Then again, you could step outside and roughly measure it yourself.
One pace should equal around three feet so you can walk the length and width of your lawn if it is a simple rectangular or square space. Simply multiply the length by the width to get your total square footage.
If you have multiple lawns, you could measure the total area of your property and then subtract the area that covers your driveway and house. Alternatively, measure each lawn separately and add it up.
Find Out What Type Of Grass You Have
Learning how much nitrogen your lawn requires means identifying what type of grass you have. This may be a process of elimination so start with which climate you are in then try to single out your grass.
Cool-season grasses are for typically colder, more arid climates such as the Midwest, Northeast, and Pacific Northwest. These conditions favor grass types such as Bentgrass, Southern Bluegrass, Fescues, and Ryegrass.
Warm-season grasses thrive in warmer climates in the Southern states. The grasses typically include Zoysia Grass, Bermuda Grass, Centipede Grass, Dichondra, and St. Augustine Grass.
A straightforward method of finding out what type of grass you have is to look at the youngest leaves.
Their arrangement from the center of the shoot is called their vernation and should either be folded or rolled in the bud. This will further narrow your search as certain types of grass, like Bluegrass, are rolled while others, such as Ryegrass, are folded in the bud.
Once you have established the vernation, try to find out how the grass grows. Specifically, if it grows out creeping apart or bunched together. Grasses such as Centipede Grass creep out while Fescue bunches together.
Even after identifying the characteristics of your grass, you can still be in some doubt as to what specific type it is.
Numerous sites will have photos where you can cross-examine samples alongside photos from your own lawn yet even that can be bewildering.
If it is still confusing, take a small sample of your lawn and speak to a lawn care professional. Not only will they help you identify the type of grass but can give you some tips on how to best look after it.
How To Find Out The Percentage Of Nitrogen In Your Fertilizer
Check the fertilizer bag itself and specifically the NPK value. This will tell you the amount of nitrogen that is contained in the fertilizer and will be the first number in that three-number series.
The other two numbers are for phosphorus (also referred to as phosphate) and potassium (potash). For instance, a 25-7-10 bag will contain 25% nitrogen, 5% phosphorus, and 10% potassium with the rest of the bag being filler material.
Next, you need to calculate how many pounds of fertilizer to apply to your lawn. This will be based on the percentage of nitrogen and how much fertilizer you are recommended to apply per year.
The recommended amounts are usually in a range that is linked to the length of the growing season. Climates that have long summers and mild winters require the upper number in that range.
Alternatively, climates with comparatively short summers need a lower number for that shorter growing season.
For instance, if the range says two to four pounds of nitrogen per 1,000 square feet then you only require two in a cold-winter climate whereas you need the full four pounds if the climate has longer summers.
If you were aiming for a single pound then with 1% of Nitrogen listed on the fertilizer bag, you would need 100 pounds of fertilizer to adequately cover 1,000 square feet.
Obviously, you would need two 50-pound bags of lawn fertilizer to get you through the year. Having double the percentage of nitrogen means halving the amount of fertilizer.
A bag with 3% nitrogen listed would only require 33.3 pounds of fertilizer over 1,000 square feet. These ratios remain the same as the percentage of nitrogen increases.
At 25% nitrogen content, you should only need four pounds of fertilizer to reach a pound of nitrogen over 1,000 square feet.
These calculations go all the way up to 46% which is consistent with urea, the fertilizer with the most potency available to buy.
How Much Fertilizer Should I Use On My Lawn?
The reason for finding out the percentage of nitrogen is to know how much you require based on the type of grass. Different types of grass require different amounts of nitrogen and this can range from one to six.
For instance, Centipede Grass only requires one to two pounds of nitrogen per 1,000 square feet whereas Ryegrass requires two to four pounds. If you apply more than the recommended amount, you may end up burning your grass.
Let’s say you have measured your lawn and it measures roughly 1,000 square feet. After heading to the garden supply store you have bought a bag of 25-5-10 fertilizer that weighs 50 pounds.
The NPK value will show that the fertilizer contains 25% nitrogen so if you applied three pounds of fertilizer across your entire lawn it would get 0.75 pounds of nitrogen per square 1,000 feet.
If you were to feed your lawn four times a year then three pounds of fertilizer would be an adequate amount for Ryegrass. For that type of grass, two to four pounds of nitrogen per 1,000 square feet is recommended.
However, for Centipede Grass only one to two pounds of nitrogen per 1,000 square feet is the recommended amount. You should switch to one and a half pounds of fertilizer so that after four feeds you have hit that recommended amount.
What Can I Do If I Apply Too Much Fertilizer?
The numbers can be quite exacting so it is best practice to double-check your calculations. Use a machine that you can know can measure and distribute fertilizer exactly how you want it on your lawn.
Should the worst happen, and too much fertilizer hits a certain spot then try to scoop it up. If that is not possible then try to flush it out with water which can help to prevent a burn.
How Often Should You Apply Fertilizer To Your Lawn
Like anything, moderation is key when applying fertilizer to your lawn.
You want to achieve the recommended amount of nitrogen per square feet yet over the course of the year. That could be once a year in a reduced amount to keep it in good condition, or four times a year to create a lush, healthier lawn.
The timing is also crucial as you want to fertilize your lawn during the period it needs to be fed the most.
The Best Time To Apply Fertilizer To Your Lawn
Of course, you should not apply all your lawn fertilizer in one go for the entire year as that can lead to burning. Instead, split your recommended amount of fertilizer feeds into four separate occasions at the right times to get the best results.
Arguably the best time to feed your lawn is in early spring. The ideal timing for that first feed is usually between February and April, just when the grass is beginning to grow. Feeding it at this point should strengthen the roots just when your lawn needs to be mowed.
Around six to eight weeks later (between April and June) you should feed it again to maintain a well-nourished lawn.
By now, summer is in full swing and that can be a tough period for your lawn due to the intense heat and increased chance of foot traffic.
Again, apply your lawn fertilizer around six to eight weeks after that previous feeding in late spring. This would be in the warmest months so between June and August.
Before winter sets in, set aside time to give your lawn one final feed so it can recover from summer. Just like the first feeding, this should help strengthen the roots of your grass and help store the nitrogen for when spring comes around.
When Should I Mow My Lawn?
Before you apply fertilizer to your lawn you should give your grass a trim then rake away any excess lawn trimmings. This will aid aeration and help the fertilizer reach deeper into the soil.
Final Thoughts
Finding out how much fertilizer you should use on your lawn should not be an exercise in guesswork. You may need to do some research to find out your grass type and from there you should know what sort of climate you live in.
Remember that the type of climate will determine how much nitrogen you should feed your lawn.
Different types of grass require different amounts of nitrogen which will determine how much fertilizer to apply each time.
If your grass does not need so much nitrogen or you only want to maintain it then buy a lawn fertilizer with a reduced amount. However, if your lawn needs to stand out then four feedings a year are recommended.
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