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How Long Does Lawn Fertilizer Take to Work?

Grow a lush, green lawn by choosing the right fertilizer for your grass. Lawn fertilizers encourage new grass growth by providing all the nutrients a lawn needs to flourish. But how long does lawn fertilizer take to work? And, what are the chemical processes behind fertilizing a lawn? Let’s find out!

How Long Does It Take Lawn Fertilizer to Work?

How long it takes lawn fertilizer to work depends on whether you use organic fertilizers or synthetic fertilizers. Quick-release fertilizers work well but may lead to fertilizer burn. Slow-release fertilizers require patience but prove much safer to use. Below, find the estimated time it takes for the most popular lawn fertilizers to work.

Fertilizer TypeEstimated Time to Work
Fast-Release Synthetic Fertilizers1-2 days
Fast-Release Organic Fertilizers2-3 days
Slow-Release Synthetic Fertilizers2-5 days
Slow-Release Organic Fertilizers2-6 weeks

The Importance of Fertilizing Grass

Almost everyone knows that lawn fertilizers promote healthy, green grass. People often think of lawn fertilizer as food for grass that helps individual blades grow faster. While rapid growth and lush green foliage are the main reasons to fertilize a lawn, a couple of other benefits are worth considering as well.

Longer Roots

Spread fertilizer over your lawn, and your grass will grow deep roots. Long roots help your lawn survive intense heat and drought. They will also make your lawn more resilient in areas with heavy foot traffic.  

Fewer Weeds

A lawn care expert may apply extra fertilizer to the bare patches of your lawn to fill them. Once the patches are full, fertilizing your lawn according to professional guidelines will create a thick, dense canopy of grass blades that will squeeze out existing weeds and prevent new weeds from growing.

What Is Quick-Release Fertilizer?

Quick-release fertilizer produces positive results within a matter of days, not weeks. Also known as fast-release fertilizer, it provides nutrients that a lawn can easily absorb.

Quick-release synthetic fertilizers often contain:

  • Ammonium nitrate
  • Potassium phosphate
  • Calcium nitrate
  • Potassium nitrate
  • Ammonium sulfate

Quick-release organic fertilizers include:

  • Fish emulsion
  • Seaweed
  • Bat guano
  • Poultry manure

Most manufacturers make quick-release fertilizer in liquid form because the nutrients easily seep into the soil where the roots can absorb them. Lawn care professionals dilute this type of fertilizer in water before application to prevent fertilizer burn.

What Is Slow-Release Fertilizer?

Slow-release fertilizer breaks down slowly to feed your lawn over an extended period. Also called controlled-release fertilizer, it takes extra time to see results, but the results are long-lasting. Many lawn care experts prefer slow-release fertilizers because they are more efficient and less likely to cause lawn burn.

Synthetic slow-release fertilizers often contain:

  • Isobutylidene diurea (IBDU)
  • Crotonylidene diurea (CDU)
  • Urea-formaldehyde (UF)

Organic slow-release fertilizers include:

  • Kelp meal
  • Cow and horse manure
  • Blood meal
  • Vermicast
  • Bone meal
  • Compost
  • Cottonseed meal

How Long Does It Take for a Lawn to Absorb Grass Fertilizer?

A lawn begins to absorb grass fertilizer almost immediately. Watering a lawn will activate slow-release granular fertilizer and help organic fertilizer reach the soil. But how long does it take for grass to absorb lawn fertilizer? Let’s find out!

How Long Does It Take for a Lawn to Fully Absorb Fast-Release Fertilizer?

It takes two to four weeks for a lawn to fully absorb fast-release fertilizer. As a result, lawn care professionals must reapply fast-release synthetic fertilizer more often than other lawn fertilizers. Applying fertilizer of this type too frequently may result in fertilizer burn. 

How Long Does It Take for a Lawn to Fully Absorb Controlled-Release Fertilizer? 

It takes six to eight weeks for a lawn to fully absorb controlled-release fertilizer. These types of lawn fertilizer break down slowly to feed your grass over an extended period. In some cases, it may even take more than eight weeks for your lawn to fully absorb slow-release fertilizers.

When Is the Best Time to Use Fertilizers?

The best time to use fertilizers depends on the type. For example, synthetic fertilizer should be applied to wet grass around dusk on a day with cold weather. That way, you reduce your risk of lawn burn. Synthetic granular fertilizer can burn dry grass on a hot day.

Your annual fertilization schedule will vary based on lawn type, location, and fertilizer preference. Most professionals apply granular fertilizer in early spring, late spring, early fall, and early winter.

How Fast Do Lawn Fertilizers Work?

Quick-release synthetic fertilizers work as soon as they hit the soil. They serve as the perfect solution when preparing for a backyard birthday party because they will make your grass greener and promote new growth in 24 to 48 hours. Quick-release organic fertilizers work within 48 to 72 hours.

Slow-release fertilizers work slowly but deliver long-lasting results, promoting root growth for new lawns. Slow-release organic fertilizer will show results within a month. It takes less than a week for slow-release synthetic fertilizer to work.

How Fast Will Lawn Fertilizer Turn My Grass Green?

If you want green grass, you need to know when you can expect to see the results you seek. Granular fertilizer made with organic materials will start turning your grass green about two to five days after you apply fertilizer. However, you will not see the full effect on the color of your grass until about seven days later.

Quick-release products are the right fertilizer to use if you need your grass to turn green within a day or two. Remember that the initial results will make your grass greener in patches. A few weeks later, the color of your grass will even out.

Can You Use a Combination of Fertilizers?

An experienced lawn care professional can tell you which type of fertilizer will help your lawn the most. In cases that involve new grass seed, a combination of fertilizers may serve your lawn the best. That way, if you forget to apply fast-release fertilizer, the slow-release product will cover you. Some manufacturers even produce granular fertilizer that contains a mix of both kinds of fertilizer. 


Should I water my lawn after fertilizing?

You should water your lawn 24 hours after fertilizing it to allow the fertilizer to settle. When you water your grass, drench it to activate all the fertilizer. Soaking your lawn will also help the uptake of nutrients into your soil. Giving your lawn little more than a quick spritz will prove ineffective at activating all of your fertilizer. 

How many minutes should I water my lawn after fertilizing?

You should water your lawn for 45 minutes to one hour after fertilizing. This rule of thumb does not account for your sprinkler system, climate zone, or lawn type. In general, you want to make the soil moist to three inches deep.

Should you mow before or after fertilizer?

You should mow immediately before fertilizer. This strategy will allow the fertilizer to reach the soil easily. Plus, after you apply fertilizer and water your lawn, you will not need to mow your lawn for at least another week.  

Can I fertilize my lawn every 2 weeks?

You can not fertilize your lawn every two weeks and expect optimal results. Fertilizing every two weeks may result in lawn burn, excess lawn waste, polluted groundwater, and toxic algae growth.

Should I Put Down Fertilizer at Night or Morning?

You should put down fertilizer as directed by the manufacturer’s instructions. Your local lawn care expert will apply the fertilizer at the recommended rates using the best possible methods. In general, early morning or late evening are the best times to put down fertilizer. Your lawn care professional will water your lawn after application to spread the fertilizer more evenly and prevent burning.

Thinking About Organic Granular Fertilizer? | Call Heroes Lawn Care

Of all the different fertilizers on the market, only organic granular fertilizers offer the unique combination of easy application and a controlled release. If you think your new lawn may need organic granular fertilizer, call Heroes Lawn Care at 844-980-LAWN to discuss which kind of fertilizer is right for your grass.

Get Started Towards a Greener Lawn