Understanding Fertilizer Burn in Plants and How to Remedy It

Barbara Gillette is an accomplished Master Gardener, herbalist, beekeeper, and journalist with three decades of expertise in cultivating and propagating a variety of fruits, vegetables, herbs, and ornamental plants.

Applying fertilizer to your plants is intended to promote robust roots and stems, lush leaves, colorful flowers, and delicious fruits. However, when it comes to houseplants, it’s often true that using less fertilizer is more beneficial. Indoor plants, confined to pots, depend on additional nutrients to thrive. Finding the right balance for each type of plant can be challenging, and using too much fertilizer can damage delicate roots and leaves.

What is fertilizer burn?

Fertilizer burn happens when a plant receives excessive or frequent feeding. The salts present in fertilizers accumulate in the soil after the roots absorb the nutrients, leading to potential harm. Typically, houseplant fertilizers are water-soluble and can be either fast-acting or slow-release. The consequences of over-fertilizing with fast-acting formulas are usually noticeable in a short period, whereas the effects of slow-release fertilizers may take as long as two weeks to manifest.

Indicators of Fertilizer Damage on Indoor Plants

Here are indicators that your plant may be experiencing fertilizer burn.

• White crust on the soil surface, whether on the inside or outside of the pot, or on the leaves and stems, indicates the buildup of salt. This is an initial warning that the fertilizer concentration may be too high or that it is being applied too frequently.
• Brown tips and edges on leaves suggest improper watering and/or fertilization. If you notice this following a fertilization, it is likely that the roots are absorbing too much salt, leading to dry and fragile leaves.
• Stunting occurs when growth either slows down significantly or halts altogether. New leaves may not emerge or may turn yellow or brown before falling off. Additionally, plants may produce flower buds that fall off before they can bloom. The accumulation of salt can draw moisture away from the roots, hindering photosynthesis and preventing new growth from occurring.
• Wilting occurs when leaves lose their firmness, becoming soft and droopy, and eventually turning black before dropping off. Stems lose their strength, which may lead to the plant toppling or collapsing. The roots may appear dried out or blackened, suffering from excessive salt, which impairs their ability to supply the necessary nutrients for the plant’s survival.

Brown tips and edges on leaves suggest improper watering and/or fertilization. If this occurs following a fertilizer application, it is likely that the roots are absorbing too much salt, leading to dry and brittle leaves.

Ways to Remedy Fertilizer Burn

If fertilizer burn is identified promptly, it can be remedied to rescue your plant.

Empty the Pot

The appearance of dry, brown tips and edges on leaves is an initial indication of fertilizer burn. Rinse the plant thoroughly with cool, fresh water multiple times, ensuring that any excess water is allowed to drain.

Place the pot beneath a running tap or let the saucer fill up before emptying it. Wait a few minutes and repeat the process. The initial rinse helps to dissolve built-up salts, while the second rinse cleans the potting mix. Ensure to drain it well, as the plant can take up salts that remain in stagnant water. Trim away any badly damaged leaves and refrain from fertilizing until new, healthy leaves start to grow.

Tip

City water supplies often have chemical salts that can lead to accumulation. If your plant is taking a long time to bounce back or frequently shows signs of salt buildup, consider using distilled water, rainwater, or boiling your tap water and letting it cool for 24 hours before using it for watering.

Repot

To address white residues on soil, pot surfaces, and leaves, consider repotting the plant. Begin by thoroughly rinsing the roots multiple times with clean water. Next, transfer the plant into a new pot filled with fresh potting soil. If there are no additional indications of fertilizer damage, you can return to a regular feeding routine, using fertilizer at half the recommended strength.

Tip

If you notice a white crust forming on the top layer of the soil, you can remove the top inch and substitute it with new potting soil. In cases where salts have accumulated on the pot’s surface or on the stems and leaves, it is advisable to repot the plant.

Trim Injured Roots

Stunted growth and wilting are signs of root damage, which can lead to rot and ultimately result in the death of your plant. Carefully take the plant out of its pot and remove any excess potting mix. Examine the roots and trim away any that are dry or discolored. For roots that are partially damaged, cut them back to where the tissue is healthy. Rinse the roots gently with cool, clean water and replant using fresh potting material. Return to your usual watering routine, but refrain from using fertilizer to allow the plant to recuperate.

As fresh buds and leaves begin to emerge, think about decreasing your fertilization frequency or thinning the concentration. If you don’t see any new growth within a month, the plant has probably fallen victim to root rot and should be discarded.

Avoiding Fertilizer Damage

While many houseplants originate from tropical regions, it doesn’t imply that they all require identical nutrient levels to thrive. It’s important to check the information labels and understand the specific needs of each plant.

• Begin with a diluted solution and monitor for any indications of nutrient deficiency. It’s simpler to enhance feeding than to remedy a plant that has already suffered damage.
• Start by watering the plants before applying fertilizer. When the roots are moist, they absorb nutrients more effectively.
• Utilize a balanced, water-soluble fertilizer designed for houseplants, unless a particular type, such as orchid fertilizer, is suggested.
• Refrain from applying fertilizer directly onto the leaves and stems.
• Regularly clean your pots every three to four months by flushing them with cool, fresh water multiple times.
• Apply fertilizer to your plants at the start of the growing season, and refrain from fertilizing during the winter to allow the plants to have a natural resting phase.

What are the signs of fertilizer burn on a plant?

Indicators of fertilizer burn consist of dry, brown tips and edges of leaves. The presence of white crust or deposits on the soil, pot surfaces, leaves, and stems suggests an accumulation of detrimental salts. More severe symptoms include stunted growth and abrupt wilting.

What are the consequences of over-fertilizing a plant?

Every fertilizer is composed of salts that can accumulate to detrimental levels, leading to the wilting and death of plant tissues. This issue may arise from using overly concentrated fertilizers, the incorrect type, or excessive application. If you notice indications of fertilizer burn, water the plant immediately. If addressed promptly, you can remedy the situation and rescue the plant.