Fertilizing your plants should result in strong roots and stems, vibrant foliage, bright blooms, and tasty fruit. But sometimes with fertilizers, less is more, especially for houseplants. Indoor gardens live in pots and rely on supplemental feeding for nutrients. Getting it right for your specific plant can be tricky and overfertilizing is a mistake that can burn tender roots and foliage.
What Is Fertilizer Burn?
Fertilizer burn occurs when a plant is fed too much or too often. Fertilizers contain salts that build up and remain in soil after roots soak up nutrients, eventually causing damage. Most houseplant fertilizers are water soluble and either rapid or slow release. The effects of overfertilizing with rapid release formulas will appear fairly quickly, while symptoms caused by slow-release formulas can take up to two weeks to appear.
Signs of Fertilizer Burn on Houseplants
Here are signs your plant could have fertilizer burn..
- White Crust: White crust that appears on the soil surface, inside or outside of the pot, or foliage and stems is salt accumulation. It's an early sign fertilizer is too strong or you're applying it too often.
- Brown Leaf Tips and Margins: Brown leaf tips and edges indicate incorrect watering and/or fertilizing. When you see this after a fertilizer application, chances are roots are taking up excess salt causing foliage to become dry and brittle.
- Stunting: Growth slows or stops completely. New leaves fail to develop or turn yellow, brown and drop. Plants form flower buds that drop before opening. Salt buildup is diverting moisture away from the roots, slowing photosynthesis and inhibiting new growth.
- Wilting: Leaves become limp and droopy eventually turning black and falling off. Stems lose rigidity. The plant may fall over or collapse. Roots are desiccated or blackened, damaged by excess salt and unable to provide nutrition the plant needs to survive.
Brown leaf tips and edges indicate incorrect watering and/or fertilizing. When you see this after a fertilizer application, chances are roots are taking up excess salt causing foliage to become dry and brittle.
How to Fix Fertilizer Burn
When fertilizer burn is recognized early, it can be corrected to save your plant.
Flush the Pot
Dry, brown leaf tips and margins are an early sign of fertilizer burn. Flush the plant with cool, clean water several times, allowing excess to drain away.
Hold the pot under a running faucet or allow the saucer to fill then dump it, wait a few minutes and repeat. The first rinse dissolves accumulated salts and the second cleans the potting medium. Drain thoroughly. The plant will reabsorb salts left in standing water. Prune out any severely damaged leaves and withhold feeding until new healthy foliage appears.
White deposits on soil, pot surfaces and foliage can be fixed by repotting. Start by flushing several times with clean water to thoroughly rinse the roots. Then move the plant to a fresh pot with new potting medium. If there are no other signs of fertilizer burn, resume a normal feeding schedule with fertilizer diluted to half strength.
Prune Damaged Roots
Stunting and wilting indicate damaged roots, which eventually rot and cause your plant to die Remove the plant from it's pot and shake off excess potting medium. Inspect roots and prune out any dried up or discolored. Prune partially damaged roots back to healthy tissue. Gently rinse with cool, clean water and repot using fresh material. Resume a regular watering schedule but withhold fertilizer, giving the plant plenty of time to recover.
When new buds and leaves appear, consider reducing your fertilization schedule or dilute the amount. If new growth fails to appear after about a month, the plant has likely succumbed to root rot and should be disposed.
Preventing Fertilizer Burn
Most houseplants are tropical in origin but that doesn't mean they all need to same amount of nutrients to stay healthy. Read information tags and learn about each specific plant's requirements.
- Start out with a diluted formula and watch for signs of nutrient deficiency. It's easier to increase feeding than to try to fix a damaged plant.
- Water first before adding fertilizer. Moist roots take up nutrients more efficiently.
- Use a water-soluble, balanced houseplant formula, unless a specific fertilizer, like orchid food, is recommended.
- Avoid wetting leaves and stems with fertilizer.
- Flush pots regularly every three or four months by running cool, clean water through several times.
- Fertilize plants at the beginning of the growing season, then stop fertilizing during winter months to give the the plant a natural rest period.
What does fertilizer burn on a plant look like?
Signs of fertilizer burn include dry, brown leaf tips and edges. White crust or deposits on soil, pot surfaces, leaves and stems indicate build up of harmful salts. Stunted growth and sudden wilting are more serious symptoms.
What happens if you give a plant too much fertilizer?
All fertilizers contain salts that can build up to harmful levels causing plant parts to dry up and die. This can happen if the fertilizer is too strong, the wrong type, or is applied too often. Irrigate the plant right away when you see signs of fertilizer burn. When caught early, you can correct the problem and save the plant.