How Long Does it Take Granular Fertilizer to Work

Adding fertilizer to your lawn or garden is a process that is precise depending on whether you’re planting grass, veggies, or fruits. Fertilizer helps your lawn and plants to grow big and strong and gives them a boost of important nutrients like nitrogen, potassium, and phosphorous. The decomposition rate will vary if you’re using an all-purpose plant fertilizer or a lawn fertilizer.

How long the fertilizer takes to decompose will depend on the type of fertilizer you’re using. Synthetic fertilizers often work instantly while organic fertilizers take about 2-6 weeks to break down into the soil. Liquid fertilizers are mostly urea-based and this compound takes about 24 hours to work, but granular fertilizer needs water to activate it and takes 2-5 days to start showing any results. However, with slow-release, it can take 6-8 weeks depending on your watering.

Plant and lawn fertilizer

Fertilizers can provide a boost to your lawn and plants when they’re not growing or producing as they should. As a homeowner, fertilizing your lawn at the right time will give you great results and fall is the best time because it’s the time your grass is actively growing and storing nutrients over winter that it will need to grow in spring.

For most gardens, you can buy a quick-release synthetic granular fertilizer if you want to quickly boost your veggies or flowers. You’ll notice some improvement after a week and it can last for 3-4 weeks. Slow-release granular fertilizers take about 2 weeks after application to decompose and start to improve your plants and can last from 2-9 months.

Types of fertilizers

Organic granular fertilizers

Organic fertilizers are better for the environment than synthetic fertilizers because they comprise of organic matter like blood meal, fish emulsion, and bone meal. This ensures that no harmful chemicals affect any nearby water bodies or sip underground. Organic fertilizers need to decompose so they can release the nutrients so they work more like slow-release fertilizers.

How long granular fertilizer takes to work will depend on the organic materials it contains, but generally, it takes 2-6 weeks to break down. Once it decomposes it will continue to nourish your plants for months or years so you get to apply it fewer times than synthetic fertilizer.

It releases important nutrients that support your plants and also contains micronutrients, potash, and microorganisms that are beneficial to your soil. 

Synthetic granular fertilizers

The best thing about synthetic fertilizers is that their nutrients are readily available without having to wait for it to decompose. So your grass and plants get important nutrients of nitrogen, potassium, and phosphorous. Most of these fertilizers have a high content of nitrogen and almost no potassium and phosphorous. Nitrogen is very important in the creation of chlorophyll which is an essential part of photosynthesis that helps plants to convert the sun into energy. That’s why nitrogen helps your grass to grow greener and helps its leaves to grow.

Granular synthetic fertilizer needs water to make it soluble for the plants to absorb it and the best time to apply it is before some light rain.

Water your lawn or garden a few days before so it’s not too dry for the soil to properly accept the fertilizer.

Liquid fertilizers

If you have never sprayed liquid fertilizer, you need to first plan for any eventualities like heavy rains so that your plants have time to absorb the fertilizer. Unlike granular fertilizer, liquid fertilizer only takes a few minutes to be absorbed by your plants. Most liquid fertilizers are urea-based which takes only 24 hours to be converted to ammonia. Depending on the temperature and humidity levels in the environment, it can take up to 5 days for it to react and even longer when it’s colder. Nitrogen is very important in the formation of chlorophyll in your plants so when your plants begin to look greener, it’s a sign that the fertilizer is working. However, if they begin to turn brown, leave start to drop, or roots rotting, you’ve used too much fertilizer. About 50% of the fertilizer you apply is lost in the first 48 hours, so make sure you water your soil properly.

Quick-release fertilizers

These types of fertilizers are also called soluble fertilizers that provide readily available nitrogen to plants and grass. They usually tend to improve your grass in a week or less and good growing conditions, after application, your grass will absorb the nitrogen into the grass blades in 15-24 hours. Although quick-release is cheaper than slow-release fertilizers, it’s more likely to burn your grass or plants if applied wrongly and its effects don’t last very long.

Slow-release fertilizers

Also called insoluble or controlled-release fertilizers, they are gradually broken down by microorganisms into available nitrogen. This slow-release nitrogen takes between 3-10 weeks to improve your grass or plants. This fertilizer will not harm your grass or plants and it will provide long-lasting effects and it’s best used during summer to provide food slowly and for longer.

When to fertilize plants

Well-managed soil with lots of organic matter is rich in both micro- and macro-nutrients that are important for good plant growth and production, but even the best-managed garden will benefit from fertilization. The only way to reap these benefits is to know the right time to fertilize your plants. If you apply fertilizer during the wrong season, it will cause the plants to grow quickly but not strong enough to survive the winter. There are different methods of applying fertilizer and whichever method you choose the time of year for fertilizing is very important because each plant is slightly different.

The best time to apply fertilizer annually is during spring to encourage leafy growth and the production of flowers and fruits. Earl spring in some areas may still experience late freeze or snow which can harm new growth because of fertilizing. To prevent harming the new growth, it’s best to wait till the last frost. The best time to use fertilizer on your plants is when they’re at their peak growing cycle.

When to use granular fertilizer on your lawn

Synthetic fertilizers work faster than organic fertilizers to feed your lawn to provide fast and visible results, but as your grass continues to depend on this synthetic fertilizer to provide a quick fix for nutrients when you don’t use it your lawn will struggle.

However, when you use organic fertilizer to feed and support your soil, you can even skip or delay an application, but your grass will still be green, resilient, and strong because your soil is healthy.

Synthetic fertilizers have a chemical composition that will most likely burn your grass if over-applied. To avoid this, you should follow the instructions on the packaging bag and ensure you water your lawn properly then spread the fertilizer early in the evening on a cool day. Make sure to evenly cover the surface with fertilizer. If you apply fertilizer on a hot sunny day, you can burn your dry lawn. Even organic fertilizer is not without its risk of burning.

The best time to apply fertilizer on your lawn is 4 times annually, but your fertilizing schedule may vary depending on the climate and type of grass, but you should spread lawn fertilizer during early and late spring and also early and late fall.

You might need to apply synthetic fertilizer for more than 4 times a year. You must water your lawn a day or two after application for both types of fertilizers. Wait for 24 hours before letting your kids and pets play on the fertilized lawn, but you don’t have to wait if you’re using organic fertilizer.

Best time to apply fertilizer

Type of lawn grass



When to apply fertilizer

Warm-season grasses

Bermuda, centipede, and Zoysia

Early spring( February to early April)

Apply a low nitrogen fertilizer (ratio of 0-0-7) and a pre-emergent from Feb to early March to prevent weed germination.

Spring ( late April to May)

When grass is green and out of dormancy, apply 5-10-30 plus iron with less nitrogen for centipede grass and 16-4-8 plus iron for Bermuda and Zoysia.

Use an organic humus compost as a top-dress as your first fertilizer application for the year.

Mid-summer (June to August)

Apply 16-4-8 plus iron as your final fertilizer application

Fall and winter ( September to January)

Omit fertilizer

Cool-season grasses

Tall fescue

Winter (December to early February)

Before spring apply one application of 16-4-8 plus iron

Early spring ( late February to March)

Apply feed fertilizer ratio of 0-0-7 and low nitrogen weed to prevent weed germination.

Spring ( April to August)

Don’t fertilize, apply fungicide once at night when its 60 degrees F or above.

Fall ( late September to November)

When the temperatures have cooled apply 16-4-8- plus iron.

In October top-dress with organic humus compost.

If you’re overseeding apply 5-10-30 plus iron to the newly seeded area.


Choosing the right fertilizer for your needs will go a long way in helping you to achieve the goals set for your lawn or garden. Whichever type of fertilizer you use, always use it correctly to avoid burning your grass or plants because of over-fertilizing. 

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