Dealing with Fertilizer Burn
Ever heard the phrase: “If some is good, more is better”? Just like too much candy will rot your teeth and too much exercise can hurt your body – too much fertilizer can harm your plants! This phenomena is known as fertilizer burn.
What is Fertilizer Burn?
Review what you know:
Plants, like humans, need to eat to grow and thrive, and do so by absorbing nutrients from the surrounding soil via their roots. It’s an effective system in nature, where fallen leaves and other debris break down and act as a natural food source. In residential and commercial landscapes, this natural cycle is broken when remove yard waste. Over time, this can deplete the amount of nutrients available to plants, causing slower growth and fewer blooms. To keep our landscapes healthy and beautiful, homeowners and landscape companies apply man-made and organic fertilizers to replace lost nutrients.
When fertilizer is applied correctly, plants are able to absorb the nutrients they needs safely. However, if the nutrient to water ratio is high (very concentrated) the mixture becomes toxic.
Did you know that most fertilizers contain salts that can harm your plants?
Most commercial fertilizers contain salts. In high concentrations, either from a heavy handed one time application or from repeated applications building up in the soil over time, these salts can cause or contribute to the dehydration of plants – sometimes to the point that otherwise healthy cells collapse and die. When this happens, the plant’s leaves often look as though they’ve been burned, hence the name: fertilizer burn.
The most common symptoms of fertilizer burn are:
- brown or reddish brown spots on leaves
- leaves wilting or developing leaves showing misshapen form
- white or slightly brownish crust develops on the plant or surrounding soil
Are my Plants Susceptible to Fertilizer Burn?
While any plant can develop fertilizer burn – potted plants, landscape plants, entire lawns, trees – some are more prone to burning than others.
- Young, tender plants that haven’t ‘hardened off’ yet
- Plants heading into dormancy – these plants tend to absorb less water and nutrients right before dormancy, causing fertilizers applied to concentrate
- Plants that are dry or sunburned are already dehydrated and less efficient with their water uptake. The salts in fertilizers exasperate the issue
- Plants sitting in direct sunlight or experiencing particularly hot weather tend to lose water faster than those sitting in cooler, shadier spots and are therefore more likely to dehydrate.
Treatment and Prevention
There’s no way to bring dead plant cells back to life after fertilizer burn, but with early intervention and a small amount of effort, most plants can be saved and returned to their former glory with little fuss.
- Remove visible fertilizer – whether it’s a crust on the soil surface or spilled powder, removing excess fertilizer is the first step
- Flush the soil with water – the idea is to dilute or remove as much of the fertilizer as possible to lower the concentration of salts in the soil around the plant
- Re-pot if needed – sometimes flushing just isn’t enough. In these situations, re-pot the plant using fresh soil as much as possible.
- Stop fertilizing – at least until the plant looks healthy again! Allow enough time for the whole plant to recover, not just the top!
- Remove damaged leaves – cut off any visible damaged portions (browned, wilted, abnormally shaped). This damage is permanent and is a weak point in the plant’s natural defenses against fungus, bacteria, and pests.
At the end of the day, the best treatment is PREVENTION – always read the label to make sure you’re applying fertilizers properly!