Granular fertilizer breaks down in about 2 weeks, but you can dissolve it in warm water in as little as a day or two and apply it as a liquid fertilizer. Granular fertilizer does require moisture to dissolve so you can speed up the process with frequent watering.
Granular fertilizers are sometimes called slow-release fertilizers. This means that they release their nutrients into the soil over time, generally 2 weeks.
If your granular fertilizer is not dissolving into the soil be sure to water it regularly and consider using a rake to break up the soil and encourage the granules to enter the soil.
Granular fertilizer that sits on the surface of the lawn may have been applied too thickly or the soil may be too compacted to facilitate the breakdown of the pellets.
Aerating the soil may improve the soil texture.
Be sure to apply granular fertilizer evenly with a hand spreader or rolling spreader to create an even layer of fertilizer.
Organic granular fertilizers will take longer to break down because organic fertilizers often contain minerals that cause them to take longer to break down than synthetic fertilizers.
Organic soil amendments or fertilizers like bone meal, feather meal, compost or organic materials can take much longer to break down and feed the soil over months or seasons.
How to Dissolve Granular Fertilizer
Granular fertilizer will break down over 2 or 3 weeks with normal watering. The granular fertilizer does not need to be crushed or prepared before application.
Organic fertilizers can take longer than synthetic because of the additional minerals in organic fertilizers.
You may also choose to use a liquid application of the fertilizer.
Granular fertilizer can be dissolved in a bucket of warm water and applied as a liquid fertilizer. Use a large bucket filled with warm water and stir the mixture every few hours and allow it to completely dissolve for 24 to 48 hours.
Granular fertilizer can sometimes contain iron and other minerals that may not dissolve completely in water, strain these particles from the mixture before using a sprayer to apply the fertilizer to avoid clogging the sprayer.
How Long Does Granular Fertilizer Last in Soil?
As a general rule, fertilizers last for one season or a few months. Manufacturers generally state a recommended frequency of application, but a soil test is the best way to evaluate the needs of your soil.
Lawn fertilizers are all given an NPK ratio, that is the amount of nitrogen, phosphorus and potassium. These are the main nutrients needed for a healthy lawn.
Granular fertilizer generally contains various amounts of nitrogen, potassium and phosphorus. Each of these compounds stays in the soil for different amounts of time. Nitrogen is the fastest to leave the soil and be used by the plants while potassium remains for many many months.
Nitrogen usually washes out of the soil in a few weeks, phosphorus 4 to 6 months, while potassium does not move readily in the soil and remains for years.
Granular fertilizers are often heavy in nitrogen to help balance the speed with which it leaves the soil.
It is recommended by many gardeners to apply additional nitrogen in between complete fertilizers when your soil conditions require it.
How Long Does It Take Fertilizer To Go Away?
Components in fertilizer leave the soil at different rates, but as a general rule, complete fertilizers will mostly leave the soil in 4-6 months.
Granular fertilizer or other soil additives can sometimes crust on the surface of well compacted soil and not enter the soil.
If your fertilizers are not breaking down consider aerating the lawn to promote healthy root growth and fertilizer absorption.
You can also consider a liquid fertilizer for your soil and plant health. You can dissolve granular fertilizer in a few days by mixing the granules with warm water and stirring frequently and allowing the mixture to sit.
Be sure to strain out any large chunks before applying with a sprayer or hose attachment.
Nitrogen is an important nutrient for lawns and gardens and it leaves the soil very quickly, 2 to 6 weeks in most cases.
It can be helpful to apply a nitrogen fertilizer a few times in a lawn’s growing season to promote a longer green lush lawn.
How Much Rain Does It Take To Dissolve Granular Fertilizer?
When applying granular fertilizer you should give it about ¼ to ½ inches of water to get the process starting. If you apply fertilizer when rain is in the forecast you can skip the watering as long as the rain saturates the ground.
In order to completely dissolve granular fertilizers you would need consistent rain of at least ½ inch a few times a week for 2 weeks or more.
Thunderstorms or heavy rains may wash away fertilizers that are newly applied.
If you have limited water you may consider dissolving your fertilizer in warm water and applying it as a liquid in conjunction with watering.
Applying granular fertilizer as liquid does increase the speed that the nutrients can be absorbed by the plants.
This can be a very water and cost effective way to apply fertilizer when you are limiting watering.
This can result in nitrogen burns if the fertilizer contains high nitrogen levels or if your liquid is very concentrated.
Is It Bad For It To Rain After Fertilizing?
If your fertilizer is designed to be watered-in, the rain will not harm the effectiveness of the application if you have applied a product like weed and feed which may require some dry time before being watered you may need to reapply.
Granular fertilizers are fine to be rained on as they break down slowly and will not be washed away by normal rain, but liquid fertilizers may wash away quickly in a summer storm.
Many gardeners recommend applying fertilizer when you will have 2 dry days after application, but each manufacturer has its own recommendations.
Be sure to read the directions for your product completely to get the best results.