How To Fix Over-Fertilized Soil (Complete Guide)

If you think you’ve over-fertilized your soil, don’t panic. It’s a common problem that I and many other gardeners have encountered at least once, and thankfully, there are a few easy-to-implement solutions to the problem.

The best way to fix over-fertilized soil is leaching excess fertilizer from the soil. Before doing this—or taking any other corrective measure—it’s crucial first to evaluate the plant’s condition and soil quality, as over-fertilization can often share similar signs to other issues.

If you’re wondering how to fix your soil, I’ve laid out an easy, step-by-step guide. I’ll walk you through everything from understanding the problem to identifying its signs and eventually fixing and preventing it.

How Over-Fertilization Affects Soil

Your soil is over-fertilized if it contains much more fertilizer than your plant can use. This often happens in outdoor gardens and lawns, but it’s a much bigger and more common problem for potted plants.

Plants need a variety of nutrients to grow. Atmospheric carbon dioxide and frequent watering provide hydrogen, carbon, and oxygen, while fertilizers provide the rest of these nutrients.

MacronutrientsMicronutrientsEssential Elements
NitrogenSulfurHydrogen
PhosphorousCalciumCarbon
PotassiumMagnesiumOxygen

Each of these nutrients has a specific function in plants, and a deficiency or excess in any will cause plants to show signs of stress. With over-fertilization, we’re typically concerned with how an excess of these nutrients in the soil affects plants.

Here are some of the common effects of over-fertilization:

Worsened Soil Structure

The primary relation between over-fertilization and poor soil structure comes from excessive soil tillage. Tilling the soil is often necessary when using solid fertilizers, as it mixes the nutrients into the soil, allowing it to permeate deeper and encouraging root growth.

Unfortunately, this can be a double-edged sword, as tilling also compacts soil over time, gradually closing soil pores and reducing nutrient-holding capacity and moisture retention.

In addition, sodium nitrate, which is a key source of plant nitrogen for many fertilizers, has been shown to affect granulation (breakdown of larger soil components into smaller, more porous ones) when applied over longer time periods.

The same studies also show a significant reduction in soil organic matter (SOM) due to the effects of intensive soil tilling and fertilization.

Environmental Impact

Fertilizers significantly affect the environment, even when they’re not used excessively. In fact, much of the agricultural regulation following the fertilizer boom at the turn of the century are directly related to the environmental effects of fertilizer overuse.

For one, fertilizer salts can be quite toxic to humans and often leach into surrounding groundwater and large water bodies. This often leads to the death of plant and animal life and can significantly affect the ecosystem in a few ways.

Decomposed organic matter is often marketed as a better choice than chemical fertilizer. But, it still has its downsides, especially when used excessively.

For example, fecal matter, which is often part of manure and compost, can carry bacteria and disease-causing pathogens. In addition, since fertilizer salts aren’t inherently bound to the soil, they often leach into surrounding land and water.

Excessive use of nutrients, like nitrogen or phosphorus, leads to algal blooms and also causes increased weed growth in the surrounding land. It’s also a significant health risk since groundwater is used as drinking water for many people.

Plant Health Issues

For most gardeners and commercial producers, plant health is the biggest concern when dealing with over-fertilization. Plants can only take up so many nutrients from the soil.

When these nutrients reach critical levels, they adversely affect plant health:

Nutrient Imbalance

Nutrient imbalances happen when nutrients in the soil are poorly proportioned. Over-fertilization won’t always mean all nutrients are in excess. Sometimes, just one being significantly more than others can cause problems.

For example, an excess of nitrogen can limit the uptake of phosphorus. So, if nitrogen is in excess, you might get corresponding signs of phosphorous deficiency, even if there’s enough of it in the soil.

One common example is that your plant won’t produce fruits or flowers when there’s too much nitrogen. Instead, you will notice more green growth.

Osmotic Stress

Plant roots generally absorb water from the soil through osmosis, which is the movement of water from an area of higher concentration (the soil) to an area of lower concentration (the roots). 

In addition, transpiration, or the release of water through the stomata in the leaves, boost the capillary action that sucks in water from the soil to the roots.

If there are too many fertilizer salts in the soil, the roots experience osmotic stress, making them lose their ability to take in water and vital nutrients. This is one of the key causes of nutrient imbalances in plants.

In worse cases, reverse osmosis can happen when fertilizer salts accumulate to high enough levels. This causes water to actually move out of the plant and into the soil. 

Water is a vital component of plant cells and is one of the key things that keep them rigid and upright. As water begins to leave the cells, plants lose rigidity, and that’s why overfertilized plants tend to droop.

In addition, the shoots will become dehydrated and discolored. This is one of the common symptoms of fertilizer burn.

Causes of Over-Fertilization

An excess of fertilizer salts in the soil is the primary definition of over-fertilization, but how do these salts accumulate, and what can conditions make it more likely?

Wrong Application Rate

Overzealous fertilizing is, in most cases, the leading cause of over-fertilized soils. Of course, fertilizer is usually good for the soil, but too much of a good thing will eventually cause problems.

You’ll notice that many experienced gardeners recommend applying fertilizers at half the recommended dosage. It’s often easier to treat symptoms of nutrient deficiency than reversing the effects of over-fertilization.

Mistimed Application

Timing your fertilizer application is almost as important as how much fertilizer you actually use. Timing is much more than just fertilizing every week or month. 

It also involves considering factors like the following:

  • The growing season
  • Plant dormancy or activity
  • What stage of growth your plant is in

Wrong Type of Fertilizer

Standard N-P-K (nitrogen-phosphate-potassium) fertilizer granules are by far the most commonly used plant food. However, the world of fertilizers is large, and you can use many types depending on your needs.

While standard NPK fertilizers provide a good balance, a soil test might reveal that you need something more. Plant appetites can also vary across different species and growth stages.

Poor Drainage

Leaching is nature’s way of “flushing” the soil. Most commonly, rainfall seeps into the soil carrying away excess salts with it. However, over-fertilization can become an issue for poorly draining soils since the water has nowhere to go.

It’s crucial to grow houseplants in pots with drainage holes and top-watering occasionally, especially during fertilization to prevent excess nutrient buildup.

For lawns and gardens, it’s highly recommended to apply fertilizers a day before the expected rainfall. That way, the excess nutrients can be flushed out of the reach of the roots.

If your soil has poor drainage and the excess nutrients remain in the root zone, your plant will likely suffer fertilizer burn.

Step-by-Step Corrective Measures

Now that you know all there is about the causes and signs of over-fertilization, it should be much easier to understand the steps involved in correcting the problem. However, the corrective measures can vary depending on where the affected soil is.

With that in mind, I’ll discuss in more detail how to treat over-fertilized soils in pots, gardens, and lawns:

Potting Soil

1. Inspect for Signs of Burn

The first thing to do once you realize you have applied too much fertilizer in the soil is to stop fertilizing immediately and check the plant for symptoms. 

The overconcentration of nutrients in the soil often causes visible signs of damage in plants. These signs occur as discoloration on your plants’ roots, stems, and leaves, which come out a few days after applying fast-release fertilizers or after a few weeks for slow-release.

Typically, these discolorations are yellow, brown, or black. In severe cases, plant leaves will appear withered. If you uproot the plant, you might also notice blackened root sections for the same reason.

When searching for signs of fertilizer burn:

Begin With the Leaves

Start with the leaves, as these show the earliest burn signs after roots. Check each leaf individually and carefully. Burns usually brown the leaf margins first, making them an excellent early sign to check for. 

Observe the Leaf Margins

Check the leaf margins for more advanced burns. Signs usually start at leaf margins moving inwards slowly. As the problem worsens, leaf tips and edges will curl and the center of the leaves turn yellow.

Assess for Blackened Roots

You’ll want to check for blackened roots as well. The blackened sections worsen with time, eventually spreading all along the roots. These are signs of cellular death. Damaged sections must be trimmed before repotting your plants

The severity of the symptoms should help you decide whether or not to remove the plants from the affected soil. In most cases, you wouldn’t even need to remove the plant, unless you see signs of root rot. If the plant shows signs of rot, you’ll need to treat the rot and transfer the plant into better soil.

2. Check the Soil Drainage

Checking the soil’s drainage is one of the first things to do to after you confirm that your plants have symptoms of fertilizer burn. Root and shoot discoloration can be due to multiple reasons, such as overwatering and underwatering.

You’ll need to perform some fast and easy confirmatory tests, which can help determine the next steps.

Since poor drainage contributes to fertilizer salt buildup in the soil, it can be harmful and inefficient to flush over-fertilized soil while the plants are still in it. 

If your soil takes too long to absorb water from the surface or remains moist for too long, these are telltale signs that there’s a problem with drainage.

You must first remove the plant and amend the soil with coarse sand or perlite before the leaching process to ensure that the excess fertilizer can be drained properly out of the potting soil.

You can then transplant salvageable plants in new pots with fresh soil with better drainage while fixing the over-fertilized soil.

Of course, the process of repotting or transplanting plants will only be crucial if the soil quality is poor and the effects of over-fertilization are severe. In less severe cases, especially if there’s no issue with soil drainage, you can leave the plant in the soil as you fix over-fertilization.

3. Remove Any Visible Excess Salts or Granules

Solid or granular fertilizers usually contain salts containing the nutrients plants need. When the soil is over-fertilized, these salts will eventually precipitate and form a white crust on the soil surface.

Fixing this is relatively straightforward:

Remove the Excess

Using a small hand shovel (or a similar straight-edged tool), scrape off any excess fertilizer from the top of the soil.

During this process, avoid taking off more than 1/4-inch (0.63 cm) of soil depth if you have any plants in the soil. Any more than this, you’ll begin to stress the plants, as it could deprive the area around the roots of whatever nutrients are left. This can also cause accidental root damage.

Replace the Removed Crust

Replace the removed crust with fresh and sterile soil. Avoid using nutrient-rich soil at this point because you wouldn’t want to introduce more nutrients to the roots for some time until they recover.

This step won’t completely solve the problem, but it will remove enough fertilizer salts that any additional measure you take will be much more effective. You can put the extracted potting soil into your compost pile if over-fertilization is the only issue. The excess nutrients can be recycled as the pile decomposes.

4. Leach the Potting Soil

When enough water enters over-fertilized soil, it redissolves fertilizer salts carrying them with it as it moves downwards beyond the reach of the roots. This process is called leaching.  

When leaching nutrients from the soil, it’s important to water deeply and thoroughly. The process requires large volumes of water to soak through the soil completely.

Leaching works best when there’s no problem with your soil’s drainage capacity. That’s why you must check the soil drainage early in the corrective steps. 

Here are some things to keep in mind when leaching potting soil:

Water With Double the Volume

You’ll need to water with double the volume of the pot. For example, a 2-gallon (7.6-liter) pot will need 4 gallons (15 liters) of water. 

Always Water Gradually

You must water gradually to ensure that the water percolates through the soil and comes out of the drainage holes at the bottom. You can do this by adding one gallon (3.8 liters) at a time, making sure that you can use up the recommended volume within the day.

Allow the Water Time to Soak

Place the pot on a drip tray and give the excess water time to exit your pot completely. Repeating the process 2-3 times with a 7-10-day interval should reduce the soil nutrients to safe levels. 

5. Add Compost to the Soil

About 2-4 weeks after the last leaching session, you can add compost to your potting soil. This will help improve your soil quality and add some high-quality but slow-release nutrients for your plants.

For potting soil without plants, you can work 2-3 inches (5-7.6 cm) of compost for every 7-10 inches (18-25 cm) of potting soil.

For potting soil with a plant, carefully work an inch (2.5 cm) of compost into the upper 2 inches (5 cm) of potting soil around your plant. If your plant has shallow roots that are at risk of damage in the process, you can just fluff up the soil surface using a hand rake or garden fork and add the compost on top.

Garden Soil

1. Check and Evaluate the Symptoms

Symptoms of over-fertilization are often similar to other gardening issues, such as over or underwatering, too much or too little sunlight, and microbial diseases. 

Garden soil also tends to compact more easily than the fluffy potting soil, especially from overwatering. Immediately leaching the soil without proving the root cause will lead to waste of water, effort, time, and plant life.

That’s why it’s crucial to rule out the other issues before treating your garden soil. Nevertheless, you must stop fertilizing your garden plants as you further evaluate the symptoms.

The common symptoms of over-fertilization include:

  • Unevenly yellow and wilted leaves
  • Brown or dried leaf tips and margins (burn marks)
  • Stunted growth
  • Premature leaf drops
  • White crust on the surface (from granular fertilizers)

One tell-tale sign that they’re due to over-fertilization is if the symptoms appear within a few days or weeks after applying fertilizers. The higher the concentration, the more severe and faster the symptoms will appear.

Over-fertilization symptoms can manifest later if you fertilize your plants too frequently although you dilute the fertilizers accordingly.

2. Check the Drainage

Test your soil’s drainage by pouring 1-2 gallons (3.8-7.6 liters) of water and observing how long it takes to get absorbed. 

If the surface remains wet for over 30 minutes or the soil feels squishy when you step on it, then you have a problem with drainage. About 2-3 days after watering your soil, remove the affected plants and transplant them to better soil. 

If you’re dealing with shrubs or trees with massive roots, you can leave them in the ground and amend the soil accordingly with sand before you go to the next step.

3. Flush the Affected Soil With Water

Heavy rainfall can often help leach the excess fertilizer from the ground. However, during dry season or if you live in an area with scarce rainfall, you’ll need to manually flush the soil using water from your garden faucet.

It can be impractical to leach the soil in wide gardens using a garden hose because the process requires large volumes of water. Instead, focus on the areas where plants are showing signs of over-fertilization.

Here’s how to do so for maximum effectiveness:

Drench the Soil

Drench the affected soil deeply and evenly with about 6 inches (15.24 cm) of water or 3.6 gallons (13.6 liters) per square foot (0.09 square meters). Since this is a large volume, focus only on the soil immediately around your shrub or tree or the area where you extracted the damaged plant. 

Provide Water Gradually

Water the soil gradually to avoid excessive pooling on the soil surface that can lead to crusting. You can pour one gallon (3.8 liters) at a time on the affected soil. Observe how quickly the soil absorbs the water and continue watering once the surface doesn’t puddle anymore.

Re-Check the Moisture Level

Check the soil moisture in 3-4 spots around the soil using a stick about 6 inches (20 cm) deep after 7-10 days. Repeat the process as soon as the stick comes out dry.

Leaching the affected area twice should be enough to reduce the soil nutrients down to safe levels for your plants. 

4. Check and Adjust the Soil Acidity

Leaching, whether naturally through rainfall or artificially by deep watering, can remove minerals from the root zone, making the soil more acidic. It’s crucial not to overdo the leaching process, as it can acidify the soil. 

Conducting an at-home soil test will tell you if you need to make adjustments to the soil pH. Luckily, most plants can tolerate slightly acidic soil with pH around 6.0-6.5. Chances are, the pH is still within optimum range for your plants.

In rare cases where the pH becomes too low, you may need to apply liming materials. Amend the soil accordingly to make it suitable for your desired plants. 

Liming your soil with ground limestone or wood ash can raise the pH, but it’ll take several months to show significant changes. 

Avoid using too much liming material in an attempt to speed up the alkalizing effect. Using more finely ground limestone or ash and working it evenly within the root zone will reduce the time it takes to raise the soil pH. 

5. Grow Cover Crops to Protect and Enhance Garden Soil

Vulnerable garden plants that are highly susceptible to overwatering during the leaching process will need to be uprooted and relocated to safer soils, such as a freshly created raised bed.

However, the newly treated soil shouldn’t be left bare because weeds can quickly take over. Weeds are more tolerant of problematic soil than your desired plants and will take advantage of the situation.

Since you can’t return the newly transplanted plants to their old place too soon, you can grow cover crops as sacrificial plants as you wait until your garden soil is ready for your desired plants. Crop rotation is often recommended anyway to keep the soil healthy.

Cover crops can help fix your soil by doing the following:

  • Protecting the soil from erosion and compaction
  • Consuming excess nutrients
  • Returning nutrients into the soil as they die out

You can use annual cover crops, such as the crimson clover. This plant is excellent because it can work as a winter or summer cover crop, making it usable almost whenever your soil has been treated of over-fertilization.

Here are some things to keep in mind when using annual cover crops:

  • Sow the seeds about 6 weeks before the first frost date for winter cover.
  • Sow the seeds a week or two after the last frost date for summer cover.
  • Deadhead the flowers before they go to seed to control some cover crops’ invasiveness.

With proper care and light fertilization using organic materials like compost, the fixed soil will be ready for your plants in the next growing season.

Lawn

1. Evaluate the Damage on the Grass

The cause of yellow or brown patches on an otherwise healthy-looking lawn can be hard to determine without confirmatory tests. 

But if you stay on top of your lawn care, you can confirm the issue by evaluating certain details. In addition, the symptoms of fertilizer burn often come out shortly after applying fertilizers—often in a matter of days.

The first step is to halt all fertilizer applications until you figure out what’s causing the damage on your lawn. Then, examine the extent of the damage.

You can rule out the issue of fungal diseases by checking the following:

The Last Time You Applied Fungicides

Whether you hire someone to manage your lawn or you do it yourself, knowing when you last applied fungicides as part of your preventative routine will rule out fungal diseases.

The Type of Grass You Have

Warm-season grasses grow best when temperatures are between 75 and 90 °F (24-32 °C). On the other hand, cool-season grasses thrive in temperatures ranging from 55 to 75 °F (13-24 °C). Outside their ideal range, they’re more susceptible to fungal diseases. Certain grasses are also susceptible to specific fungal diseases.

The Pattern and Color of the Damage

Fungal diseases often have distinct patterns (i.e. ring spots) and discoloration effects (i.e. rust) on grass. Researching the symptoms of common fungal diseases affecting lawn grass will help you confirm or rule out fungal infection as the cause of damage.

2. Deeply Water the Affected Area

Once you’ve ruled out fungal diseases and confirmed that over-fertilization is the culprit, it’s time to flush the soil. 

Use 6 inches (15.24 cm) of water to flush the affected area. For instance, if you the affected area is a one-square foot (0.09 square meters) patch, pour 3.6 gallons (13.6 liters) of water into it. You can pour 1 gallon (3.8 liters) at a time with one-hour intervals.

Step on the soil before pouring the next batch of water to ensure that the soil is absorbing the water well. If the water doesn’t pool around your shoe, it means the soil has adequate drainage. 

In most cases, you have to flush the affected lawn area only once because turfgrasses have shallow roots reaching only 6-24 inches (15-61 cm) deep. A single flush followed by normal watering will also keep the excess fertilizer beyond the reach of young roots when reseeding.

3. Reseed the Bare Patch

About three to five days after the leaching session, rake the pale patch of grass to roughen up the underlying soil and replenish the bare area with sandy soil.

Raking the soil surface will increase the chances of germination once you lay out the seeds.

Here are some values to keep in mind:

  • Work about 2 inches (5 cm) of compost into 6-8 inches (15-20 cm) of soil to ensure that the area has adequate drainage and aeration.
  • Spread 2-3 grams (0.07-0.10 oz) of grass seeds over every square foot (0.09 square meters) of bare soil.

Grass seeds take 7-21 days to germinate, depending on the species and environmental conditions. 

Specifically water the reseeded spot on days outside your regular lawn watering schedule, especially when it doesn’t rain. The goal is to keep the upper inch (2.5) cm of the soil moist as the grass roots grow.

With proper care and extra precautions on fertilizer applications, your new seedlings will grow stronger and your lawn grass will recover its lush appearance.

How to Prevent Over-Fertilization

As you can see, treating over-fertilized soil can be a tedious process. Therefore, it’s crucial to prevent it from happening in the first place. If you’ve just leached your soil of excess fertilizer, it’s even more important to prevent the issue from reoccurring.

Below are some helpful tips to avoid over-fertilizing your soil:

Choose the Right Fertilizer

There are numerous types of fertilizers, but not all of them work for all plants. Choosing the right kind of fertilizer for a specific purpose or kind of plant will go a long way to benefit your garden without the risk of over-fertilization.

Some common types of fertilizers include:

Single-Nutrient 

Single-nutrient fertilizer is ideal if your soil lacks only a specific nutrient as shown by your plant’s symptoms. For instance, chlorosis or the yellowing along leaf veins is a sign of iron deficiency. In that case, you can use chelated iron and avoid all-purpose fertilizers which can risk an overdose of other nutrients.

Multi-Nutrient 

All-purpose NPK fertilizers are popular among gardeners because they contain the three essential macronutrients: nitrogen, phosphorus, and potassium. Some brands even incorporate trace amounts of calcium, magnesium, zinc, and other essential micronutrients. 

Be mindful of the NPK ratio because each plant will need different proportions and a balanced fertilizer will not work for all plants. For instance, leafy greens need nitrogen-rich fertilizers, whereas most bulbs and flowering plants need more phosphorus.

Inorganic Fast-Release

Inorganic fertilizers are made synthetically to mix minerals and compounds that can break down in the soil and feed plant roots quickly. However, they don’t do anything else to improve the soil quality.

These fertilizers are often used on fast-growing plant species at the start of the growing season, especially if the plants are heavy feeders. They should be applied at intervals that gradually become larger until the application stops at the end of the growing season.

Some common examples include:

  • Ammonium nitrate
  • Potassium nitrate
  • Aluminum sulfate
  • Diammonium phosphate
  • Potassium chloride

These fertilizers are likely to cause over-fertilization or salt buildup if soil conditions aren’t suitable for chemical reactions that would break them down and make them readily accessible for plant use.

When using these fertilizers, watch out for the following soil parameters to avoid overfertilization:

Moisture

These fertilizers need enough water to facilitate hydrolysis or breakdown of compounds into ions that can be absorbed by the plant roots. That’s why you must water the soil adequately for the fertilizers to work.

pH

Most plant nutrients are accessible to the roots at pH levels between 6.2 and 6.8, with 6.5 being the optimum level.

Temperature

Inorganic fertilizers dissolve quickly and more effectively at warm soil temperatures (around 60 °F or 15.6 °C). That’s why it’s best to apply fertilizers during the warm season to prevent them from sitting too long in the soil and causing plant damage.

Organic Slow-Release

Organic fertilizers like compost and animal manure release nutrients into the soil slowly as they are broken down by soil microbes. That said, you soil should have plenty of beneficial microbes to effectively send the nutrients from organic fertilizers to plant roots.

This fertilizer is ideal for slow-growing plants that don’t require high amounts of nutrients immediately at the onset of the growing season.

In addition to a slow, gentle release of nutrients, organic fertilizers also present the following benefits:

  • Improved soil structure
  • Better nutrient absorption
  • Improved water retention
  • Increased microbial activity
  • Increases cation exchange capacity 

Liquid

Liquid fertilizers are fast-acting and can be made from organic or inorganic sources. They’re usually applied as a foliar spray or soil drench formula. Either way, they’re only necessary for fast-growing plants that need a quick source of nutrients.

To avoid leaf or root burns from using liquid fertilizers, you must dilute the product properly. Apply the formula only during the growing season and at the cool parts of the day, such as a few hours before sunrise. 

You must also water the plants well within 24 hours to rinse off the excess nutrients on the foliage and send them to the soil.

You can apply liquid fertilizers every 2-3 weeks at the beginning of the growing season and gradually increase the interval by a week as the season progresses. This will help you ease out on the application without an abrupt halt that can be harmful to heavy feeders.

Granular

Granular fertilizers are generally slow-release and need to be watered in to be activated. They can be used as a side or top dressing, working it into the topsoil for a gradual release of nutrients every time you water your plants.

They typically last 2-5 months in the soil and need to be applied once during the growing season.

However, one downside of using this type of fertilizer is that it can heat up the soil around your roots as it undergoes chemical reactions. That’s why it’s common to apply it on the surface of the soil about an inch (2.5 cm) away from the base of the plants.

Dilute Liquid Fertilizers to Half the Recommended Strength

I can’t stress this tip enough. Under-fertilization can be a problem, as it won’t bring out the best your plants can offer. However, it’s easier to deal with than the effects of over-fertilization. 

Liquid fertilizers are often highly concentrated with organic or inorganic plant nutrients. Each product has specific dosage and dilution instructions but they might not always be ideal for your soil quality and plant species.

When unsure about your soil’s nutrient needs, always err on the side of caution and use diluted fertilizer. A good rule of thumb is to use half-strength on heavy feeders and ¼-strength for light feeders and slow-growing plants.

You can then observe your plant’s response by evaluating the quality of the existing foliage and new growth. Due to the fertilizer’s fast action, you’ll see symptoms of nutrient imbalance in a matter of days and make adjustments from there.

Be Mindful When Fertilizing Potted Plants and Houseplants

Pots have a cramped space and overgrown roots have access to almost every corner of the soil. There’s also not much space for excess nutrients to go that won’t damage your plant’s roots. Therefore, the damage caused by over-fertilization can be more severe in potted plants.

To prevent such issues, you must follow the recommendations below:

Have Adequate Drainage in the Soil and Pots

Both the soil and the pot need adequate drainage to prevent the risk of over-fertilizing your houseplants. Note that excess nutrients and fertilizer salts can sit in the root zone indefinitely without proper drainage.

The soil should be porous enough to allow water to seep through and flush out the excess nutrients. That’s why most potting mixes contain good amounts of perlite or pumice. 

If your potting soil doesn’t have them, you can amend it by adding up to 25% perlite. It can be costly at first but highly beneficial in the long run.

Another important thing to consider when growing houseplants is the use of pots with drainage holes. Such pots don’t only protect plants from overwatering issues but also allows the excess fertilizer salts to be leached out of the soil.

Leach Houseplants Regularly

Many indoor gardeners swear by the benefits of bottom watering houseplants. Although the process is admittedly excellent when it comes to hydrating the soil evenly, it doesn’t allow for the leaching of toxic nutrient concentrations from the soil. Instead, it brings fertilizer salts to the surface.

That’s why it’s crucial to water your houseplants from the top regularly. You can top water your plants once a month or more frequently, especially on days when you apply fertilizer. That way, the excess salts can exit through the drainage holes.

Plan an Efficient Garden Layout

If you’re new to gardening and don’t have technical knowledge about xeriscaping or hydrozoning, don’t fret. There are some basic details about gardening that can help increase your chances of keeping your garden alive for years.

With proper planning, you can evade some common garden problems, such as over or underwatering, sunburn, pests, diseases, and even fertilizer burn.

Group Your Plants Based on Similar Growth Needs

Like with indoor gardens, it’s crucial to group outdoor plants based on their light and soil needs. But of equal importance is that you should also consider their watering needs. That’s where the concept of hydrozoning lies.

With hydrozoning, you must group plants with similar water needs so that you can water them at the same frequency. Note that some plants are drought-tolerant and there are those that require consistent moisture.

This concept can prevent issues with over-fertilization because it ensures that you don’t miss your watering schedule, especially on days when you fertilize your garden plants.

Apply Fertilizers Locally

Each plant within a specific group will still have different nutrient needs. That’s why it’s crucial to maintain proper spacing and apply fertilizers locally on plants that need them. 

Indiscriminately applying fertilizers allover the garden soil will result in some sections thriving while others are dying. This is especially true when you incorporate the fertilizer in sprinklers or drip irrigation systems.

Plan Ahead When Designing Lawns

A lawn with neatly mown grass makes for an amazing sight in front of any home. However, the amount of work that goes into ensuring and maintaining such beauty is no laughing matter.

Fixing a damaged lawn can be costly and exhausting, so it’s crucial to prevent common issues like poor drainage, compaction, and over-fertilization.

In this section, you’ll find how these three issues are connected:

Install Sprinklers Strategically for Even Water Distribution

It can be impractical to use a garden hose when watering lawns because of the large area. You also risk uneven distribution of water, leaving some sections susceptible to drought stress. 

It’s best to use a sprinkler system that can add a set amount of water gradually but evenly. An automatic sprinkler system can also help you save time, water, and money in the long run. In addition, you can conveniently add liquid fertilizer to the system during the fertilization season.

Ensure Proper Drainage Throughout the Lawn

Turfgrasses are more resistant to compaction and foot traffic. Deeply rooted cultivars are also more drought-tolerant. However, it’s still crucial to ensure that the entire lawn has proper drainage. 

This will prevent water from pooling in certain sections that can lead to sick-looking patches due to overwatering in such areas. Uneven drainage can also cause fertilized water to become concentrated in certain patches that will soon show signs of over-fertilization.

You can ensure proper drainage on your lawn by topdressing it with ½-1 inch (1.3-2.5 cm) of compost and raking it evenly into the topsoil at the beginning of the growing season.

For lawns with cool-season grasses, you can topdress the soil with compost in the fall around two weeks before the first frost. For warm-season grasses, you can do it a week after the last frost.

Water Your Lawn Thoroughly

About two days before your fertilization schedule, it’s best to water your lawn thoroughly. This will help prepare your soil and adequately hydrate your grass, making them ready to absorb the nutrients and prevent issues with fertilizer burn.

Mow the Grass a Day Before Fertilizing

It’s often recommended not to mow the grass immediately after applying fertilizers to prevent potential stress. So the best time to mow the lawn is a day before applying fertilizers. 

Don’t worry about the grass clippings catching some of the fertilizer. As they decompose, they can return some nutrients to the ground. In addition, as long as you water the grass well after applying fertilizers, there should be lower risks of over-fertilization.

Apply Fertilizers Evenly

You can add the diluted liquid fertilizer to your lawn sprinkler system or garden hose nozzle for a gentle application. 

When broadcasting crushed granules over your established lawn, you’ll need to water the lawn evenly and deeply to remove the granules from the blades. As mentioned, the granules can heat up and cause physical damage when left too long on grass blades.

Do a Soil Test Once a Year

Doing a soil test annually, just before the growing season, can help prevent over-fertilization and improve the overall quality of your lawn. 

Many private labs offer detailed tests if you’re new to gardening and unsure how to use a home-testing kit.

Unlike home tests, you’ll get a lot of extra information like:

  • Soil structure
  • Soil organic matter content (SOM)
  • Electrical conductivity (EC)
  • Precise pH values
  • Macronutrient levels
  • Micronutrient levels
  • Soil texture
  • Nutrient mobility

A detailed analysis will provide you with information on the amount of nutrients still available in your soil and give you a clear vision of what and how much to fertilize your soil.

Common Related Questions

Can Plants Recover From Over-Fertilizing?

Excess nutrients in the soil are harmful, and with time, they destroy the root structure and cause visible burns on the plants. 

If you catch the problem early enough, you’ll usually be able to correct it. Liquid and fast-release inorganic fertilizers are water-soluble and can be leached more quickly than slow-release and granular fertilizers.

Once you’ve leached the soil, avoid fertilizing until your plants resume normal growth. You’ll also need to trim off any damaged leaves.

Note that this only works if the problem hasn’t advanced excessively. If the root system is significantly damaged or the plant shows no signs of improvement after a month, the plant likely can’t be saved.

How Long Does It Take for Fertilizer Burn to Go Away?

Fertilizer burn should go away after 2-4 weeks of adequate care. Your plants will need proper hydration during this time to remove traces of salts that caused damage. In addition, give your plant as much sun and humidity they need to thrive.

However, if the problem is too advanced or you start corrective measures too late, the plant will take longer to recover from fertilizer burn. Sometimes, they might not even recover at all. 

Does Rain Help Fertilizer Burn?

Rain is nature’s way of leaching the soil, and this happens regardless of whether your soil is fertilized or not. Over-fertilized plants can often recover on their own with adequate rainfall to wash away excess minerals.

However, too much rain can worsen the situation if the soil has poor drainage. Heavy rains can cause waterlogging and make your already sensitive roots more susceptible to fungi-caused rot.

Can You Water Too Much After Over-Fertilizing?

You risk overwatering your plants when treating over-fertilized soil through leaching or flushing using large volumes of water. You must consider your plant’s health and soil drainage before leaching the soil of excess fertilizer salts.

If your plant has moderate-to-severe symptoms of fertilizer burn, with multiple discolored leaves and roots, you must first remove the plant from the soil, prune the damaged sections, and transplant it in another pot or area in your garden with better soil.

For lawns and gardens with larger and more established plants, it can be impractical to clear the ground of plants. The best thing you can do is amend the over-fertilized soil to improve drainage capacity before leaching it. This will reduce the risk of overwatering your plants.

Conclusion

Over-fertilization can be a deep and complex problem. While an excess of nutrients is the primary cause, underlying secondary causes like poor drainage, weather, and mistimed applications can make sometimes make it hard to pinpoint and solve the problem.

Evaluate the plant’s symptoms and the soil’s quality, such as pH and drainage, to arrive at the best solution. Manually removing salt crusts on the soil surface and leaching the affected soil often reduces soil nutrients to safe levels for plants.

Conducting soil tests and planting cover crops are optional solutions, but they can help guarantee that your soil is in perfect condition for your new plants.

Dr. Moritz Picot

Dr. Moritz Picot is a horticulture enthusiast and the founder of TheGrowingLeaf.com, where he serves as the lead content writer. He established the website in 2022 as a valuable resource for both gardening aficionados and beginners, compiling all the gardening tips he has accumulated over the past 25 years. Alex has a passion for nurturing plants, transforming backyards into inviting spaces, and sharing his knowledge with the world.

Recent Posts