How Long Does Fertilizer Last In Soil?

Fertilizer provides many nutritional benefits for the soil and the plants that grow there. Some all-purpose fertilizers and fertilizers work for specific plants. But no matter what type of fertilizer you're using, you may be wondering how long it will last in the soil. How long will it continue to provide benefits for your plants? We've done the research to answer this question.

Several factors determine how long fertilizer lasts in soil. This is because different fertilizers are made of different chemicals and ingredients. Some of the factors that determine how long fertilizer lasts in soil include:

  • Whether the fertilizer is liquid or granular
  • The purpose of the fertilizer
  • If the fertilizer is organic or not

Knowing the above factors can help you know how long fertilizer lasts so you know when and how often to apply it and how long you can expect to see its benefits. If you're interested in purchasing fertilizer, these factors can help you determine which kind to buy. We'll cover each of these factors in more detail in this article. For more information, please continue reading.

fertilizing garden plants in summer. Gardener hand in glove doing seasonal yardwork. How Long Does Fertilizer Last In Soil

How Long Does Fertilizer Stay In The Soil?

Fertilizers can last in the soil anywhere from seven days to several months. The exact amount of time that fertilizer lasts in soil will vary depending on the type of fertilizer you have and the formulation of the fertilizer.

Some fertilizers are also made to target specific plants. Plants grow at different rates, so some of the fertilizers for those plants are meant to last the entire growing season (such as grass fertilizer, for example). 

Other fertilizers are more beneficial to plants when they are applied every couple of weeks. Usually, this is the case with fertilizers designed to target flowers. Ultimately, how long a fertilizer lasts depends on how quickly it breaks down or is absorbed by a particular plant.

Liquid Vs. Granular Fertilizer

Yellow gloved hand holding a green scoop with fertilizer. How Long Does Fertilizer Last In Soil

There are two main categories of fertilizers: liquid (wet) fertilizer and granular (dry) fertilizer. Liquid fertilizers have become more commonly used because they are easier to apply.

They can be used initially during the planting process and again during the middle of the growing season. This type of fertilizer can be sprayed directly onto the plant, where they are absorbed by the leaves to be immediately used by the plant.

Granular fertilizers are found in the form of granules. Unlike liquid fertilizers, they are dry and can't be applied directly onto the plant. This type of fertilizer is usually applied to the soil before planting. This allows the fertilizer to break down into the soil as the plant grows. The nutrients are then absorbed by the roots for the plant to use.

Both wet and dry fertilizers contain similar nutrients. But because of how they are applied and used by the plant, there is a distinct difference in how long each lasts. Whether or not your fertilizer is wet or dry is the most significant factor in how long it lasts in the soil.

How Long Does It Take For Wet Fertilizer To Break Down?

Because the plant absorbs wet fertilizer to obtain nutrients, it doesn't necessarily break down. Whether the fertilizer is applied to the soil or the leaves, the nutrients found in wet fertilizers are immediately available for the plant to use, so they don't last as long as dry fertilizers. 

The exact formula for liquid fertilizers will vary based on the brand and type of plant that the fertilizer is meant to target. But regardless of which liquid fertilizer you use, you will have to apply it more often throughout the plant's active growing season.

Most liquid fertilizers will only last in the soil for about one to two weeks before they have to be reapplied. The exact time will vary depending on the type of fertilizer you have, but generally, you will have to use them every seven to fourteen days. The packaging should tell you exactly when to reapply fertilizer to the soil and plants.

How Long Does It Take For Dry Fertilizer To Break Down?

Dry fertilizers are typically solids that have a crystallized structure. They are sprinkled over the soil and mixed in with it upon initial planting, where they break down as the plant grows. The rate that it takes the solid crystals to break down depends on the size of the granules and the overall health of the soil.

In general, though, dry fertilizers are absorbed by plants a lot more slowly than wet fertilizers are. They last longer than a couple of weeks and are designed to last several months since they break down more slowly. Some dry fertilizers may even last a couple of seasons, so you'll only need to apply them twice a year.

How Long Does Fertilizer Last Once Applied? 

Fertilizer pellets spraying from spreader

Liquid fertilizers generally only last a couple of weeks no matter what type of plant they are used on. Dry fertilizers have a greater variation in how long they last depending on the type of plant they are made for.

Flower and Vegetable Vs. Grass Fertilizer

In flowers and vegetables that have a shorter growing season, some dry fertilizers may last throughout the growing season, while others may need to reapply every few weeks or months. It depends on the specific formula of the fertilizer and how quickly the fertilizer can be broken down and used by the plant.

Grass fertilizers tend to last longer. Grass has a longer growing season, so fertilizers are made to be broken down more slowly so that they can be used for several months. Usually, grass fertilizers only need to be applied once during the spring and again during the fall.

The time of year you apply the fertilizer can also determine how long it lasts. For flowers and plants that grow in the spring and summer, fertilizer won't last as long due to environmental factors such as heat and rainfall. Fertilizers applied to fall-growing plants will likely last longer because cooler temperatures and less rainfall mean that they don't break down as quickly.

Click here to see this flower and vegetable fertilizer on Amazon.

See more: 15 Best All-Purpose Plant Fertilizers [Liquid, Powder, and Granular]

Organic Fertilizer

Organic fertilizers are thought to be better for the environment because they don't contain synthetic chemicals. This type of fertilizer works by replenishing nutrients that are naturally found in soil.

They also enrich the soil with bacteria and other microorganisms that can improve the overall health of your soil.

Examples of nutrients released by organic fertilizers are potassium and nitrogen, and other micronutrients that plants need. They are the most beneficial to plants. However, they also take the longest to work. This is because they have to decompose fully before they fully release their nutrients. But when fully decomposed, they can provide nutrients to your soil for several years.

How Long Does It Take For Fertilizer To Work On Plants?

liquid fertilizer being sprayed unto flowers

The amount of time it takes for fertilizer to work on plants depends on the type of fertilizer and how long it takes to break down. Liquid fertilizers work the fastest because they don't have to break down. The plant roots and leaves instead absorb them, so they will begin to work almost immediately. 

Dry, granular fertilizers and organic fertilizers work a lot more slowly since they have to decompose. Some fertilizers start to release their nutrients as they begin to break down. Others may not work until they break down completely. This can take anywhere from a couple of weeks to a couple of months.

That's why it is recommended to apply most dry fertilizers to the soil in spring before planting or when planting. This allows the fertilizer time to break down and begin working as the plant sprouts and begins to grow. Reapply the fertilizer based on the timeframe established on the packaging to ensure that it provides nutrients throughout the growing season.

How Long Does Nitrogen Stay In Soil?

If you do regular soil testing, you'll have more knowledge of what your soil needs. Nitrogen is one of the most beneficial nutrients for plants. If your soil is low in nitrogen, you'll want a fertilizer that is made explicitly for replenishing it. But of course, you'll want to know how long those fertilizers last.

Again, it just depends on whether or not you use a wet or dry fertilizer. Liquid fertilizers that replenish nitrogen can last anywhere from two to six weeks. Granular fertilizers tend to be slow-release and can last anywhere from two to five months. The packaging should tell you how often the nitrogen fertilizer will last and when to reapply it.

Click here to see this slow-release nitrogen fertilizer on Amazon.

See more: Compost Vs. Fertilizer - What's The Difference?

In Closing

As you now know, fertilizers can last in the soil anywhere from seven days to several months. The type of fertilizer and its components can certainly play a role in how long it lasts in the ground, too.

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