When it comes to fertilizing your lawn, you’ll be wasting your time and money if it’s too cold outside. You probably know that fertilizing in early spring and in the fall are key steps to achieving a thriving, healthy lawn. But how early is too early, and how late is too late to throw down some fertilizer on your lawn? When is it too cold to fertilize lawn areas and get good results?
Today I’ll discuss how you can balance the reality of wanting to fertilize early and late in the season, with the science behind how cold temperatures affect how your grass utilizes fertilizer.
Planning for the cold and supporting your lawn as it transitions into and out of dormancy is an essential skill that is difficult to master. Hopefully after this article, you’ll be better prepared.
Let’s start with the basics.
When It’s Too Cold to Fertilize
As a general rule, you should not fertilize your lawn when it is dormant. Lawn grass can go dormant when it’s too cold, or too hot. At the cool end of the spectrum, you want to be sure that your air temperatures are consistently 60 degrees Fahrenheit or warmer. This will ensure that your lawn is coming out of dormancy in the spring, and not yet entering dormancy in the fall.
Fertilizing your lawn at this temperature will allow your grass to fully utilize the nutrients you’re providing.
Frost and Your Lawn
Frost can develop on your lawn when it’s too cold outside and a lot of moisture is in the air. The dew freezes as it settles on your lawn during cold evening temperatures.
Despite common belief, there doesn’t tend to be frost in the coldest parts of the winter because it’s so dry outside. The frost season tends to be very early in the spring and late fall. By the end of October (at least where I live in New England) frost occurs regularly.
It’s common to think that you should never fertilize when you begin to see frost on a regular basis. But that’s actually not true. Sometimes you can continue to fertilize your lawn as late as early December.
Grass root systems stay active until the soil is frozen. As a result, mid- to late-November can be a great time to fertilize in many areas. The soil is unlikely to be frozen at that point, so even if you’re seeing frost and your grass has stopped growing, your plants can still utilize nutrients.
Most of the best fall lawn fertilizers are high in potassium, which helps protect grass from extreme changes in temperature.
You Shouldn’t Fertilize Too Early in the Spring
Fertilizing too early in the spring when the weather is still wintry will waste your fertilizer.
Your grass will still be dormant and won’t be able to use those nutrients before they’re washed away.
Weeds, on the other hand, may be in your lawn waiting to be fertilized to get a jump start on your grass. Fertilizing too early will likely only benefit them.
Fertilizing too early in the spring is also a problem is because it can make grass focus too much on shoot growth, not root growth. You need healthy and deep roots for a healthy lawn. Supporting healthy root systems with spring fertilization sets your lawn up for the stresses of a hot summer.
The best time to fertilize in spring is when the daytime temperatures are in the 70s on a consistent basis.
When this is the case, soil temperature should be in the 60s. This temperature range is essential for successful fertilization in the spring.
Pay attention to the weather and time your fertilizer application accordingly. You don’t want to fertilize your lawn early when it’s too cold, and especially not too late when it’s too hot.
Remember the Growth Cycles of Your Lawn
A great rule to remember is that fertilization is most effective when applied during your grass’s active growth phase. When that period occurs depends on what type of grass you have and your region and climate.
If you live in northern states, you probably have a cool-season grass. Meanwhile, warm-season grasses do best in southern regions.
If you have a cool-season grass, your lawn has two main growing periods. Cool-season grasses include:
- Tall and fine fescues
- Kentucky bluegrass
One growing season takes place in the early spring after the grass comes out of winter dormancy. The other occurs in the early fall. These grasses can look tired, dull, or even go dormant during the dog days of summer.
Warm-season grasses were first created in tropical areas and do well in warm regions like those found in the southern United States.
There are five main types of warm-season grass, which include:
- Centipede grass
- Bermuda grass
- Kikuyu grass
- St. Augustine grass
- Zoysia grass
Warm-season grasses have their peak growing season in midsummer. These varieties of grass are very resilient and can withstand poor and salty soils. However, they go dormant once temperatures start dropping into the 50s.
Combinations of Cool and Warm-Season Grasses
Homeowners in transitional zones that have wide temperature swings throughout the season may have grass that is a combination of cool-season and warm-season grass types.
If this is the case for you, you will have to do different kinds of care at different times of the year, and your lawn care schedule may be more complex and challenging.
Different grass mixtures have different peak growth seasons. You’ll need to find out what your grass’s peak season is depending on your seed mixture.
Other Tips for Effective Fertilization
Beyond fertilizing your lawn when it isn’t too cold, there are more things to consider to get the most out of the money you spend on lawn fertilizer.
Plan well in advance and create an effective fertilization schedule for your lawn.
If you want to take good care of your lawn, you must have your lawn care schedule set before you need to do the tasks involved. You don’t want to be caught by surprise before the first frost. Make sure you have the aeration equipment and fertilizer you need, otherwise it will be too cold to fertilize your lawn.
You should aerate your lawn before the first frost. If your lawn needs dethatching, you should do that too.
Aerating your lawn before winter gives your lawn the chance to take in as many nutrients as possible before winter dormancy. It will also help to deal with compaction that may have occurred in the summer. Increased foot traffic in summer usually leads to increased compaction during that season.
Apply Fertilize Based on Instructions
Always carefully read the label and instructions on the lawn fertilizer that you buy. You need to know how long it will last, when you will need to re-apply fertilizer, and how much fertilizer to spread per square foot.
If you go with a granular, slow-release fertilizer, it will slowly provide your lawn with the nutrients it needs over a period of time. Time periods can range from two to eight months. This kind of fertilizer does not need to be spread in your yard as often as a quick-release, synthetic fertilizer (like those from Scotts or Pennington).
Make sure you don’t over-fertilize your lawn as you may do more harm than good.
Don’t Fertilize a Vulnerable Lawn
You should never apply a nitrogen-rich fertilizer to a dormant lawn. Applying fertilizer when it is too cold and your lawn is not yet growing will only encourage any weeds to grow and take over.
If there is a drought, you might want to avoid fertilizing your lawn until it’s over. This is because when you apply fertilizer you’ll need to water your lawn several times to make sure those nutrients get into the soil (but don’t over-water or fertilize before a downpour … you don’t want your nutrients washed down storm-drains and into nearby waterways).
If the fertilizer is left sitting on top of the grass blades for too long, you could end up with burned grass blades.
Timing is Everything When it Comes to Fertilization
When fertilizing your lawn, doing it at the right times of year (and at the right temperature) is key to success. Grass grows best when the proper nutrients are administered at the best time.
Grasses grow differently in different regions. When and how you apply fertilizer depends on what type of grass you have, and where it’s growing, but it is too cold to apply fertilizer when your grass is dormant.
Pay attention to the packaging instructions on your fertilizer as you apply it, and make sure that your air temperatures are consistently 60 degrees Fahrenheit or higher.