Feeding plants the macro and micronutrients they need by applying fertilizer is necessary to ensure that they can grow well and produce large yields. However, getting over-enthusiastic with the fertilizer can dry out your plants and lead to plant burn.
Plants need several weeks to recover from fertilizer burn, though the exact length of time depends on the damage done and the type of plant. Your plant will need to regrow the roots and leaves lost to fertilizer burn, which can take anything between one week to four weeks.
This article will explain what fertilizer burn is, what signs to look out for, and how you can fix fertilizer burn in your plants. I’ll also explain how you can prevent fertilizer burn in your plants, so read on!
Understanding Fertilizer Burn
Fertilizer burn refers to root or leaf scorch caused by excess fertilizer. If your plants show signs of wilting, yellowing, student growth, or brown spots on the leaves soon after you’ve applied fertilizer, they’re likely suffering from fertilizer burn.
Fertilizer burn occurs because the soluble salts in inorganic fertilizers draw the water from the plant tissues. This leads to desiccation, where the plant becomes extremely dehydrated due to losing water to the fertilizers.
This affects the plant’s primary functions, but it also makes it impossible for the plant to utilize any of the nutrients supplied by the application of fertilizer.
Typically, when fertilizer salts draw out water from the plant, they start at the roots. The root tissues of the plants die first, so by the time you see scorching on the leaves, the root system would have already undergone severe damage.
Fertilizer burn is more likely in hot, dry climates when plants are already struggling to retain water. When applied to dry soil, the fertilizer will not be dispersed to the deeper roots like in well-irrigated soil. If the fertilizer doesn’t get wet, it will sit on the surface, drawing any moisture in the soil and leaving the plant dehydrated.
Seedlings and newly repotted plants are especially sensitive to fertilizer burn, as their root systems are not as robust as that of established plants. This is why any starting fertilizer applied to seedlings must be heavily diluted before use.
The fragile root systems of repotted plants are why you should only mix in slow-release or organic fertilizers with your potting soil.
Organic or slow-release fertilizers will ensure that the plants are only exposed to a little fertilizer at a time. With only a little fertilizer present, the salt concentration will be too low to draw water out of the roots of the plants.
Fertilizer burn draws water out and dries out the plants, causing a burnt appearance or scorch marks on the leaves.
Fertilizer burn happens when too much inorganic fertilizer is applied to plants. This increases the salt concentration around the roots of the plants, which draws the water out of plant tissues. Fertilizer burn also happens when fertilizer is applied without irrigating the soil.
Primarily, fertilizer burn is caused when plants are abruptly drained of moisture, causing the plant to look burnt. This draining may be caused because you added too much fertilizer to your plants or because there wasn’t enough water in the soil in the first place.
In hot and dry weather conditions, the soil will be extremely dry, so even if you follow instructions and only add as much fertilizer as recommended, you might still burn your plants.
It’s important to irrigate the soil thoroughly before adding fertilizer. If you have heavy rains, wait till a couple of days after a heavy rain to fertilize your plants so you can make use of the improved soil moisture content.
Signs to Look Out For
Sometimes, things happen, and you end up burning your plants with fertilizer. And that’s alright. But catching fertilizer burn early is crucial to ensure that you can rescue your plant and correct the damage before it kills your plant.
Here are the signs of fertilizer burn in plants:
Wilting leaves are one of the first signs of fertilizer burn in a plant. As the salts begin to draw water out from the plant tissues, the leaves will droop or shrivel up.
Plants need water for a number of functions, including the transport of nutrients and minerals up and down to the leaves and roots. When water is pulled out of plants, they cannot get the nutrients to the new roots and leaves, stunting their growth.
No Blossoms or Fruits
Producing fruits and flowers requires a lot of energy expenditure, which is why people fertilize their ornamental and fruiting trees and plants. If your plants haven’t flowered after applying fertilizer, you might be looking at a case of fertilizer burn.
When leaves start to die, they start yellowing. If your plants are not over-watered or under-watered, then the yellowing may be a sign of fertilizer burn.
Browning Leaf Tips and Edges, Brown Spots, and Speckling
These brown features are the most common signs that something is wrong with your plant. If the edges are extremely dry, you’ve been watering your plant, and it’s not sitting in direct sunlight, it is likely a case of fertilizer burn.
Brown spots and speckling can either be sunburn or fertilizer burn, so if you see the spots after adding fertilizer, you know what it is.
Browned and Limp Roots
Healthy roots in plants are usually a white, cream, or off-white color. Yellowing, browning, and limpness indicate that the roots aren’t receiving enough nutrition. If they’re squishy, they’re overwatered, but if they’re dry soon after you’ve applied fertilizer, it’s fertilizer burn.
The Salt Crust on the Soil Surface
Inorganic plants are made of salts, and these salts leave residue behind when the liquid evaporates. If you see a crust of salt on top of the soil, the fertilizer didn’t penetrate the soil surface. The fertilizer then burns your plants by staying on the surface.
Immediate Steps to Mitigate Damage
Fertilizer burn can kill roots, leaves, and other plant tissue very quickly, so it’s important to prevent it.
However, if you find that you have already burned your plants, here are some steps you can take to fix them:
Water Your Plants
The first thing you need to do when you notice signs of fertilizer burn is to water your plants thoroughly. The water will dilute the fertilizer, dissolve the salts, and help return the moisture that the salts drew out from your plants. If your plant has only wilted or developed some yellowing, then watering should be sufficient.
Prune the Leaves
It’s important to remember that once the leaves start yellowing, they’re dying. There is no way to revive dead tissue, so prune away the yellow and brown leaves from your plants so they can focus on sending water and nutrients to the healthy leaves and recover faster.
Flush and Prune the Roots
If you notice browning in your leaves, the roots are likely browned as well, and the fertilizer burn has already done significant damage. Simply watering your plants won’t help.
It is best to remove the plant from the pot, prune away the browned roots, and flush the remaining roots with water to clear them of minerals.
Repot Your Plant With New Potting Soil
If your plant exhibits signs of severe fertilizer burn, your potting soil will be too saturated with fertilizer salts to be usable. You need to repot your plant with fresh potting soil and a new pot to ensure that no remaining salts can touch your plants. Ensure that your potting soil doesn’t have any fertilizer mixed in.
Keep It Out of Direct Sunlight
Burned plants still need sunlight, but it’s important to ensure that the light is gentle, so it doesn’t burn the already sensitive leaves. Keep your plant in the shade or a curtained window that receives morning light.
While you can rescue plants that are suffering from fertilizer burn, the affected leaves and roots will need to be pruned and regrown. The process is stressful, and your plants will take several weeks to return to their healthy selves. It will also set back your yield times and quantity.
Rather than trying to fix fertilizer burn, it’s better to prevent it by using organic fertilizers like compost or other inorganic slow-release fertilizers like fertilizer spikes. Slow-release fertilizers will last a long time and release fertilizers in small amounts that will not lead to desiccation.
When using regular inorganic fertilizers, always water your plants thoroughly a day before, and dilute your fertilizers according to the package instructions. Always apply fertilizers at lower than the recommended concentration on the package.
Plants can take one to four weeks to fully recover from fertilizer burn. To help plants with fertilizer burn, you need to flush the soil and prune the dead foliage. If the damage is extensive, prune the dead roots and repot the plant in fresh potting soil.
It’s easier to prevent fertilizer burn than help fix it, and you can do so by using organic or slow-release fertilizers or using your inorganic fertilizers at a much lower concentration than recommended on the package. Ensure that your plants are thoroughly watered before applying any fertilizer.