9 Ways to Save Over-Fertilized Plants

All plants need nutrients to grow, but some gardeners provide more than a plant can uptake. Excessive fertilizer can be just as detrimental as nutrient deficiencies. Depending on the type and amount of fertilizer used, you may be able to save your over-fertilized plants with quick action and patience during recovery. 

An overload of plant nutrients is similar to an overdose of vitamins or eating a meal so large that it makes you sick. If you notice a salty crust on the soil surface, yellowing leaves, or stunted growth, your plant may be suffering from over-fertilization. In extreme scenarios, fertilizer burn can defoliate or kill a plant. 

Whether you’re dealing with potted houseplants or outdoor garden vegetables, here are 9 ways to save over-fertilized plants and prevent future issues.

How Do You Save Plants From Too Much Fertilizer?

If you add too much fertilizer to your plants, the leaves may turn pale yellow, brown, scorched, wilted, or defoliated. The overload of nutrients is particularly problematic when water evaporates and the soil dries out. To save them, first remove any visible fertilizer from the surface. If there is a salty crust, scrape it away and scoop out any fertilizer granules. 

Next, thoroughly flush the plant with a lot of water to leach out the fertilizer. If growing in a container, repot your plant into fresh soil and water generously. Remove any damaged foliage and wait several weeks or months before fertilizing again. As plants recover, ensure adequate sunlight, water, and mild temperatures to reduce overall stress. 

9 Ways to Save Over-Fertilized Plants

Fertilizer is helpful for plant growth, but it’s easy to go overboard. If you accidentally dumped too much fertilizer on your plants, you may notice that they look sick. Many synthetic fertilizers are full of salts that damage plant roots and make it difficult for the plant to uptake water. An overdose of nutrients can also “burn” the leaves because the mineral salts in the fertilizer draw moisture away from the plant, leading to dehydration. 

To fully understand how to save your fertilizer-burned plants, imagine what you might do after accidentally eating a gigantic meal that leaves you feeling sick: get rid of excessive nutrients in the bathroom, drink lots of water to flush through your system, get plenty of rest, and avoid eating for a while until you feel better again. While the human overeating analogy isn’t perfect, these clues are somewhat similar to what you can do for your overfed plants. 

Identify Symptoms of Over-Fertilization

Over-fertilization can be difficult to identify for the untrained eye because the symptoms resemble plant diseases and nutrient deficiencies. But when you look closer, you can see the signs of excessive fertilizer. These symptoms are sometimes called “fertilizer burn” because the leaves take on a burnt or scorched appearance due to an overload of salts and subsequent dehydration. 

As soon as you see one or more of these signs, you need to take action. If you wait too long, the plant may lose too many of its leaves to recover. Young plants or newly transplanted specimens are the most at risk because their root zones are not established.

Scoop Out Visible Fertilizer

The easiest first step is removing visible fertilizer. If you used a granular or powdered product, it will be easy to scoop it out with a trowel or spoon. It’s OK to remove some of the upper soil layers during this process. Dispose of as much fertilizer-contaminated soil as possible without damaging the roots of the plant. 

If you use a liquid product, the fertilizer may create a white crust over the soil surface that looks similar to salt. Many people don’t realize that synthetic fertilizers are primarily salts. The mineral salts cause significant damage because they dehydrate the soil and the plant roots, making it very difficult for the plant to uptake enough water to regenerate itself.

For organic amendments like manure and feather meal, it may be more difficult to remove the product because you mixed it into the soil. Additionally, the signs of overfertilization typically appear much later because the nutrients in organic amendments are slow-release, meaning they aren’t immediately available to the plant. 

By the time the plant shows symptoms, the amendments are already thoroughly incorporated into the soil. In this case, you’ll want to use the dilution and transplant methods described below.

Flush Potting Soil with Water

After visible granules or crusts are removed, it’s important to leach the nutrients from the soil. The water will “grab” the soluble nutrients and carry them out of the soil profile, helping the plant’s root system heal from over-fertilization. This process is easier for potted plants because you can control the conditions more easily. 

Place the container outside or in the sink. Use room-temperature water to drench the plant until water pours out of the bottom drainage hole for several minutes. Avoid using excessively hot or cold water, as this will only cause more stress. 

Water for much longer than you usually would. While we are usually cautious about overwatering in container-grown plants, this instance is an exception. You want to fully flush the fertilizer out of the soil, even if it means that it is completely saturated with water. The root zone can dry out later. If the plant is highly prone to root rot, you can transplant it with the instructions below.  

Flood the Root System of In-Ground Plants

A lot of irrigation is necessary to save over-fertilized plants growing outside in the garden. You will need even more water to flush the excess nutrients out of an in-ground bed. If a liquid fertilizer was used, it could already be deep in the soil profile, burning the plant roots with an overdose of nutrients.

Use a garden hose to flood the soil around the plant’s root system. Depending on the plant’s size, you can leave the irrigation to drip at the base for 30 minutes or longer. A noticeable circle of saturated soil will surround the root zone. It will be dark-colored and very soggy.

Use the plant’s height as a gauge to estimate the width and depth of the root zone. The roots are usually at least as deep and wide as the canopy. So a mature over-fertilized tomato will need to be flushed with water for much longer than a small petunia plant with symptoms of fertilizer burn.

Preventing Environmental Issues with Nutrient Leaching 

The continuous stream of water will leach excess nutrients out of the soil. If synthetic nitrates are used, this can be problematic for local water resources. Synthetic nitrogen leached from lawns and agricultural fields is a major cause of the Dead Zone in the Gulf of Mexico, and it can cause similar issues in streams and rivers. The quick-release nitrogen creates an overgrowth of algae on the water surface that causes a lack of oxygen in the water beneath, ultimately killing the fish and aquatic life.

Of course, the easiest prevention is avoiding synthetic nitrates. But if you already over-fertilized with a synthetic product, don’t fret. You can do a few things to help protect the local ecosystem. If your garden slopes or you notice a place downstream where the water collects, fill this area with lots of wood chip mulch. This will collect the nutrient-filled water before it runs off into storm drains, roadside ditches, and local waterways. 

You can also create buffer zones around any water sources in your garden. Plant aquatic, water-loving plants around the borders of ponds and streams, and allow quick-growing weeds to pop up to soak up all the extra nutrients. You can always pull them and dispose of them in a few weeks.

Wait for Water to Drain

Plants cannot recover from stress overnight. Patience is an important next step. Wait for the water to drain from the soil, and don’t irrigate again until the soil is moderately dry. For potted plants, you should visibly see the water draining out of the bottom drainage hole into the saucer or sink. Wait several days for the moisture to fully leach out, and then water again.

Outdoor plants require a longer period of recovery. If your garden soil drains very quickly, you may do another flush of water in a few days. However, well-drained soil is typically high in sand or silt, which leaches nutrients more easily. Soils with high clay content tend to hold on to more nutrients and water, which means you’ll have to wait longer for them to dry out before you can water again.

As a general rule of thumb, wait two to three days and then check on the plant again. It will still be far from a full recovery, but you can gauge the soil moisture level and consider whether or not you need to flush the soil again. If any fertilizer crusts or granules are still visible, another flood of water may be needed. However, take care not to drown the plant, or it may succumb to root rot and die anyway.

Remove Damaged Foliage

Use a clean pair of pruners or garden scissors to cut off damaged leaves. Any leaves that are excessively yellow, brown, misshapen, or wilted can be removed, but avoid removing more than two-thirds of the plant’s foliage. Slightly pale or yellow leaves can be left behind to regenerate as long as they don’t appear diseased or infested with pests.

Take note that aphids and other sap-sucking pests are often magnetized to over-fertilized plants. Excess nitrogen is proven to attract aphids because the insects are seeking nutrients to fuel their growth. The pests can also sense that your plant is stressed and its defenses are down, making it easier to infest the leaves. It is very important to remove pest-infested leaves and take preventative action. Apply diluted neem oil or horticultural oil to the foliage to kill aphids and deter other bugs.

An over-fertilized plant is already facing a lot of stress, so saving it requires preserving as much of its energy as possible. Be very careful with the leaves and stems, and avoid breaking off large portions of the plant. A clean cut with scissors is more effective than ripping or shredding leaves off. Anywhere with an open wound is susceptible to infection, especially for perennial semi-woody and woody plants.

If a large proportion of the plant’s leaves were damaged, you may want to move it to a location with slightly less intense sunlight. Outdoor plants can be partially shaded with shade cloth or row cover to help them recover in a milder environment.

Transplant if Possible

After all these steps, some over-fertilized plants are still difficult to save. Transplanting is the best last-ditch effort to rejuvenate the plant back to full health. 

Moving the plant to fresh soil is particularly advantageous if you suspect that the roots have been damaged by excessive fertilizer salts and/or root rot. You can completely remove the plant from the over-fertilized environment and allow it to reestablish without the pressure of residual soluble nutrients in its root zone.

However, this is a slippery slope because an overfed plant is already under so much stress. You must take extreme care to avoid further damage to the leaves or roots.

Avoid transplanting plants that have lost more than two-thirds of their foliage or those that are sensitive to root disturbance (like squash, cucumbers, and tender houseplants).

Avoid Feeding for Several Weeks or Months

After recovering from an excessively satiating meal, you may not feel hungry for quite a while. Your plant needs plenty of time to recover without the influx of more nutrients. Avoid feeding the plant for several weeks or even months. Vegetable crops may be able to get by on the residual nutrients in the garden soil, especially if it is rich in compost. 

Potted plants may need nutrients sooner if their soil is already poor and leached of nutrients. Wait until you see green new growth from the top of the plant before adding any more fertilizer. Your best bet is to avoid all quick-release synthetic fertilizers that may cause overfeeding issues in the future.

I recommend only applying a tiny bit of diluted kelp solution to a plant recovering from over-fertilization. Kelp provides trace minerals that reduce stress, prevent transplant shock, and boost overall plant vigor. However, it doesn’t add significant levels of NPK macronutrients that may pose more issues.

Avoid Synthetic Fertilizers 

The best way to save plants from over-fertilization is to prevent it in the first place. Avoid synthetic, quick-release fertilizers that megadose plants with nutrients all at once. Specifically, avoid nitrogen and nitrate products, as these are often the cause of over-fertilization.

It is safer to use slow-release organic amendments that gradually provide plant minerals as soil microorganisms make them available. These fertilizers are easier for beginner gardeners to use because their dosages are more flexible. Still, you should carefully follow the directions on the package and never apply more than recommended. When slowly introducing nutrients back to damaged plants, use only one-half of the recommended dose.

As you’ve learned, a huge dose of fertilizer won’t always make your plants grow faster. In fact, it can often do more harm than good. It’s usually best to err on the side of caution and add less fertilizer than you think you need. If you feel uncertain about how to feed your plants, opt for slow-release organic fertilizers that pose less risk for nutrient overdose.