If you search online, you will literally find a myriad of answers to the question, “when to fertilize lawn.” Some say fertilize heavily in the spring, and some say in the fall. Moreover, you’ll find conflicting answers about when to fertilize lawns from reputable experts. So, what is it? What’s the best time to apply fertilizer?
Before we offer our experienced-backed response, keep in mind that your specific climate and grass type may impact when you apply fertilizer to your lawn. The frequency for fertilizing grass and the type of fertilizer you choose may also affect your lawn fertilizer schedule. That aside, our lawn fertilization recommendations are based on general fertilizer information designed for most grass types.
When Is the Best Time to Fertilize Your Lawn?
It depends on your grass. For cool-season lawns (Kentucky bluegrass, perennial ryegrass and the fescues), the most important feeding of the year is in late summer or early fall, around Labor Day, according to UMass Extension. The second is a spring feeding once the lawn is actively growing, which is May in most of the Northeast. Warm-season grasses such as Bermuda and St. Augustine are fed from late spring through summer, once they have fully greened up.
Spring Fertilizer
Spring is a great time to apply fertilizer to lawns because they’re emerging from winter dormancy and can benefit from a nutrient boost to support their active growth. You can give your lawn its first feeding in early spring. Consider using a soil thermometer to ensure your soil is above 55 degrees Fahrenheit before you apply fertilizer.
Summer Fertilizer
During the summer, applying fertilizer is safe if your lawn is growing well and is healthy. If your lawn is stressed or dormant, don’t apply nitrogen fertilizer. Choose a safer option like non-burning fertilizer or slow-release fertilizers for your lawn.
Fall Fertilizer
You can use fertilizer in the fall to store nutrients during the winter to ‘winterize’ your soil. Also, during early fall, your lawn may be searching for nutrients to help it repair itself from summer damage caused by mowing, foot traffic, etc…
Types of Fertilizers
The main fertilizer you can apply to your lawn includes liquid, granular, organic, and synthetic.
Granular Fertilizer
Many people like to use granular lawn fertilizer because it’s either time-release or slow-release. This basically means that it doesn’t feed your lawn essential nutrients all at once; it releases them gradually, which guards against burnout. Too much fertilizer will burn your grass. Slow-release fertilizer is preferable for many busy gardeners because you don’t have to make as many applications.
Liquid Fertilizer
Liquid lawn fertilizer is also popular because you can apply the product easily with a garden hose rather than a drop spreader. Unlike granules that need time to break down in the soil (hence, their ‘slow release’ action), liquid fertilizer delivers immediate essential nutrients to grass roots.
Organic Fertilizer
Organic fertilizer is made from living or once-living natural material (i.e. compost, grass clippings, bone meal, manure, etc…). Organic fertilizers may take more time to break down than synthetic nutrients, but they also tend to have more micronutrients, such as calcium.
Synthetic Fertilizer
Synthetic lawn fertilizers are formulated with essential nutrients your lawn needs, like nitrogen, phosphorus, and potassium. Synthetic formulations of fertilizers offer specific nutrient ratios, which may be important if your lawn is deficient in particular nutrients. With synthetic lawn fertilizer, you can feed it exactly what it needs to become a healthy lawn. Read the fertilizer label to find out its precise ingredients.
To choose the best fertilizer for your lawn, it may be helpful to conduct a soil test. A soil test enables you to see what nutrients your lawn needs–and which ones it doesn’t. You don’t want to deliver more fertilizer than your lawn needs, or you can burn out the roots and promote weed growth. To choose the best fertilizer for your lawn, you need to be aware of your lawn type and its specific nutrient needs. Feeding your lawn proper nutrients is part of a good lawn care routine.
Understanding Your Grass Type
Grass type matters when it comes to selecting lawn fertilizers. Cool-season grasses and warm-season grasses have different needs.
Cool Season Grasses
Plan to fertilize cool-season grasses like Kentucky bluegrass once in late spring, when the lawn is actively growing, and again around Labor Day, which UMass Extension calls the most important feeding of the year. A late-fall feeding after the last mowing is optional. The schedule table below has the details.
Warm Season Grasses
Apply lawn fertilizer to your warm-season grasses when they’re fully greened up after winter dormancy. In the deep south, where there isn’t a winter dormancy period, warm-season grasses can be fertilized in early April. Fertilize your warm-season grass during the summer months when it’s actively growing and into the fall.
Special Note about Warm Season Grasses and Fertilizer
Check with your city or county before you apply fertilizer to your warm-season grass. Some local governments set fertilizer blackout dates when residents are barred from applying nitrogen or phosphorus fertilizer, because it is more likely to wash into waterways during periods of heavy rainfall. In Florida these rules are set locally, not statewide. St. Lucie County, for example, bans nitrogen and phosphorus fertilizer from June 1 to Sept. 30, and many other Florida counties and cities have similar summer bans.
The complete lawn fertilizer guide
Timing is only half of a fertilizer plan. The rest is how much nitrogen to put down, which type of fertilizer to use and what your soil test says. The schedule below pulls it together for a Northeast cool-season lawn, and the cards link to the details.
Cool-season lawn fertilizer schedule (Northeast)
| When | What to do | Source |
|---|---|---|
| Spring | One feeding once the lawn is actively growing. UConn names May as ideal, and Connecticut bans lawn fertilizer before April 15. | UConn |
| Summer | Irrigated lawns only, with at least half (ideally three-quarters) of the nitrogen slow-release. Skip drought-dormant turf. | UMass |
| Late Aug – early Sept | The most important feeding of the year for cool-season grass, around Labor Day. | UMass |
| Late fall (optional) | After the last mowing, while the grass is still green. Connecticut stops in mid-October. | UMass, UConn |
How often should you fertilize your lawn?
Count pounds of nitrogen, not bags. UMass recommends 2–4 lb of nitrogen per 1,000 sq ft a season for Kentucky bluegrass, perennial ryegrass and tall fescue, and 0–2 lb for fine fescue. UConn says about 2 lb a year is usually enough if you leave the clippings on the lawn, and never more than 1 lb of water-soluble nitrogen in one application. For most lawns that works out to two to four feedings a year. The nitrogen calculator converts any bag into pounds of N.
Timing
Season by season
Types
Choose a fertilizer
Soil and nutrients
Feed what the soil needs
Tools
Fertilizer calculators
Sources: UMass Extension, BMPs for lawn turf: soil and nutrient management · UConn Soil Nutrient Analysis Lab, Suggested fertilizer practices for lawns
When to Fertilize Lawn FAQs
When should you NOT fertilize your lawn?
You should not fertilize your lawn if it’s already been fertilized recently. Too much fertilizer is not conducive to a healthy lawn. Rather, it can burn your grass roots. Also, do not fertilize your lawn when the weather forecast is for extremely high temperatures or heavy rainfall.
How many times should you fertilize your lawn?
Generally speaking, opt to apply lawn fertilizer 2-4 times per year. However, take the health conditions of your own lawn into account. Be sure to research the specific care needs of your cool-season grass or warm-season grass before you fertilize your lawn to be safe.
When should you fertilize your lawn in spring?
You can fertilize your lawn in spring when the soil temperatures reach or exceed 55 degrees Fahrenheit. This may be early spring in the south or late spring in the north.
Should you fertilize your lawn before or after mowing?
Plan to mow your lawn before you apply fertilizer. You may also want to aerate your lawn before your first fertilizer application.
