No one wants to be told what to do – and when to do it –
When it comes to caring for your lawn, you have a number of dos and don’ts.
Fertilizing your lawn during cooler temperatures is a don’t.
If you’re wondering what temperatures are too cold to fertilize your lawn, you’d probably like to know:
Temperatures below 60-70 degrees Fahrenheit are too cold to fertilize your lawn. It is during these temperature ranges that the lawn prepares for a dormant state to protect itself from cooler temperatures.
If you fertilize your lawn during temperatures below these benchmarks, you will simply feed the weeds and also stunt root growth of your lawn.
Check The Soil
Too many people think there is a magical date that you should apply your lawn fertilizers.
Too many people also think that just because the other town applied fertilizer, then they should also be applying fertilizer to their lawn.
Unfortunately, it isn’t that simple.
The weather conditions and temperatures can be so different to have a universal “start fertilizing your lawn” day.
When the winter comes, your lawn goes into dormancy.
It would be analogous to being asleep; your lawn had a good feeding in the fall, and now it is going to sleep for the winter.
If you fertilize your lawn when it is too cold, then your lawn will not come out of its dormant stage, and won’t be able to utilize the fertilizer you put down. The weeds will, though, and your lawn could end up having a weed infestation.
Fertilizing when it is too cold can also promote shoot growth instead of root growth.
You will get a green lawn for a very limited period of time, but if the roots aren’t given an opportunity to develop properly, your lawn will fade very quickly.
If you want to be confident about when you can safely apply fertilizer to your lawn, and not just guessing, combine the use of a soil thermometer and from past experience with this soil temperature map.
Soil thermometers are not difficult to use. You need to insert the probe approximately 3 inches into the soil and check it on a venous basis.
The soil temperature map is also not difficult to use, simply enter your location and you can determine the current soil temperature, 24-hour average temperature, and the 5-day average temperature.
By experience: By combining the two methods, you can minimize inaccuracies from daytime temperature spikes with your soil thermometer, and inaccuracies from average temperatures of the area.
Different Types of Grass
The variety of grass in your yard will also affect what ‘too cold’ is.
There are two forms of grass:
- cool-season grass
- and warm-season grass.
If you are wondering about your grass’ temperature threshold for applying fertilizer, then you more than likely have cool-season grass.
Cool-season Grass
If you live in USDA Hardiness Zones 1-6, then you may have cool-season grass. Not sure what zone you are in? Please check out the Hardiness Zone section to figure out your region.
Cool-season grass is much happier in, well, cooler temperatures.
Cool-season grasses should be fertilized twice in the spring and twice in the fall and ignored during the summer months.
If you cannot manage to fertilize your lawn four times a year, the absolute best time to fertilize your lawn, is in the fall.
Warm-season Grass
Warm-season grasses are kind of the opposite of this. They grow in USDA zones 7-10 and have no problem living in the heat.
When we get to zones 7-10 it’s kind of a strange range because some of those zones actually go below freezing, and then there are others that are hot for a good portion of the year.
That’s why I can’t have “Fertilize Your Lawn Day”.
If soil temps are above 70 degrees, I would recommend fertilizing your lawn every 4-8 weeks.
If you can’t put that much time into fertilizing, the most important time to fertilize your lawn is in late spring.
Important Temperatures
| Degrees | Cool-Season Grasses | Warm-Season Grasses |
|---|---|---|
| 55 Degrees | Spring: This is when your grass starts growing. Apply fertilizer at this soil temperature. Fall: This is around the time your lawn will start going dormant. Apply fertilizer at this soil temperature. | Spring: Cool-season weeds start growing at this temperature. Do not fertilize. Fall: Your lawn will grow slowly, or become dormant at this temperature. Do not fertilize. |
| 65 Degrees | Spring: Your lawn will grow like crazy. Mow twice a week if you can. Fertilize at this soil temperature. Fall: After a warm summer, your lawn will start growing again. Fertilize at this soil temperature. | Spring: Your grass will begin to grow at this temperature. Apply fertilizer at this soil temperature. Fall: At this temperature, your lawn growth will begin to slow down. Apply fertilizer at this soil temperature. |
| 70 Degrees | These temperatures are too high to fertilize your soil. | Fertilize your lawn once every 4-8 weeks at these temperatures. |
| 80 Degrees | Give your lawn plenty of water to stop it from going dormant to protect itself from the heat and decrease how often you are mowing your lawn. These temperatures are too high to fertilize your soil. | Fertilize your lawn once every 4-8 weeks at these temperatures. |
Cool-Season vs Warm-Season Grasses
Final Thoughts
I really hate to be bossy, but do NOT fertilize your lawn in cold temperatures!
Sure you’ll waste your fertilizer, and promote floral growth, while stunting root growth.
Cool-season grasses can be fertilized down to about 55 degrees Fahrenheit. But leave it alone if soil temperatures are colder than that!
For warm-season grasses; please do not fertilize if soil temperatures are around 65 degrees Fahrenheit.