A popular topic this time of year for cool season lawns is Nitrogen Blitz. This dedicated approach to feeding your lawn in the fall can provide many benefits for the remainder of the growing season. Read some frequently asked questions, and answers, about Nitrogen Blitz below.
Nitrogen blitz is feeding your lawn in the late summer/early fall with 0.5 lbs. of Nitrogen per 1,000 sq. ft. every two weeks. The idea of nitrogen blitzing is to put down a total of 1 lb. of Nitrogen per month for every 1,000 sq. ft. prior to the end of the season (when top growth begins to slow and stall).
Nitrogen blitz will force some growth, help thicken up your turf, and green-up your grass. The frequent feedings of a nitrogen blitz helps reestablish thin lawns that struggled in the summer months by providing plenty of food for the remainder of the season.
After the heat and drought from the summer months, plenty of stress has occurred. Cool season lawns will slowly begin to self-recover with cooler temps. This is the time to feed the lawn and push some growth.
The extra nitrogen will help root growth even when the top growth has slowed down. Nitrogen that is not used this calendar year will be stored overwinter and help your lawn green up much faster the following spring.
For cool season lawns, this will start sometime in late August/early September and run through the end of the season (e.g. Mid-October for my area of Massachusetts). You can add an organic fertilizer such as Milorganite on your first 1-2 applications, as these fertilizers contain slow-release nitrogen and often need the heat from the soil (and water) to activate. But after that, as temperatures start to drop, you will switch to a fast-release nitrogen such as urea.
CX DIY (CarbonX) is a great option. It’s a 24-0-4 formula which means 24% of the bag is Nitrogen – 17% of which is fast-acting urea nitrogen. To apply 0.5 lbs. of Nitrogen of CX DIY on a 12,000 sq. ft. lawn, you would need 25 lbs. of fertilizer every two weeks. Try our lawn fertilizer calculator to help measure.
However, this may get expensive rather quickly. A 45 lbs. bag of CX runs $59.99. So for an 11,000 sq. ft. lawn, one bag will cover two applications of Nitrogen Blitz (a one month supply at 0.5 lbs of N/1,000).
That same 11,000 sq. ft. lawn could buy 46-0-0 urea nitrogen from Amazon for the same price tag, but now get twice the amount of applications from the 50 lbs. bag (~12 lbs. of fertilizer over 11,000 sq. ft. = 0.5 lbs. N/1,000). So resource your nitrogen fertilizer wisely. Check your local nurseries and hardware stores.
Make sure your lawn mower us ready to go! With all the nitrogen being applied, be prepared to mow often. Frequent mowings during nitrogen blitz will help ensure you’re adhering to the 1/3 rule (never mowing more than 1/3 of the grass blades at a time) and help thicken your turf.
Another thing to be mindful of during nitrogen blitz is that urea (or fast-release nitrogen) requires water to get into the soil, activate the nitrogen and allow the roots to uptake the nutrients into the grass. So be sure your irrigation is working, and keep an eye on the weather forecast. As the season progresses, frost is imminent. So time your nitrogen applications and watering schedule accordingly.
Finally, stop feeding when the grass begins to slow down its top growth. This is a good indication that the temps are too cool, and the grass will start to store the nutrients for the long winter break. This timing can vary depending on where you live, but for Massachusetts this is sometime around Halloween. Continue to mow, preferably in the afternoon, a few weeks after your last nitrogen blitz application.
I’m located in Massachusetts and my nitrogen blitz feedings began last week. Generally my final applications to prepare my lawn for winter will be 10-0-20 Winter Survival, fast-acting lime, and a curative rate application of 14.3 Propiconazole just prior to the ground freezing.
If you want more in-depth details of nitrogen blitz, The Lawn Forum has many great posts and discussions around this topic. If you have any questions regarding your cool season lawn, please leave a comment below!
Nitrogen Blitz Calendar (5,000 sq. ft. yard example)
Amount (0.5 lbs. N/1,000)
|Aug. 29||Milorganite/Organic||42 lbs.|
|Sept. 12||Carbon X (24-0-4)||10.5 lbs|
|Sept. 26||Urea (46-0-0)||5.5 lbs|
|Oct. 10||Carbon X (24-0-4)||10.5 lbs|
|Oct. 24||Urea (46-0-0)||5.5 lbs.|
(Note: these dates are contingent on your location. This table is used a general guide and one that could be used for Northeast, specifically Massachusetts. The products were rotated to show diversity in the fertilizers you can use).