A chalky white crust sat on the soil of my Meyer lemon by the east-facing kitchen window. The leaf margins had scorched to a dry yellow-brown, just days after I gave it an extra feeding to push more fruit. I ran my finger across the soil and it left a powdery streak. I flushed the pot with plain water until it ran clear from the drain holes, and the new leaves came back green.
Yes, too much fertilizer yellow leaves is a real and common problem. Over-fertilizing leaves a salt buildup in the soil that yellows and browns the leaf edges and tips first. The damage is called fertilizer burn, and it shows up fast once the salts pile up around the roots.
Here is the mechanism. Fertilizer is made of mineral salts, and your plant only uses so much at a time. Whatever it cannot take in stays in the soil and pulls moisture away from the roots. This is the same reason salt draws water out of a slug. The roots dry out and get damaged, even when the pot feels wet to the touch. With less water reaching the far ends of each leaf, the tips and edges burn yellow and then brown. The center of the leaf often stays green for a while, which is a clue in itself.
The pattern of the damage is your biggest tell. Fertilizer burn starts at the outer edges and tips, where water arrives last, and works inward. The burned parts feel dry and crispy, not soft or mushy. A white or yellow salt crust on the soil surface or around the pot rim is the clearest sign that over fertilizing plants caused the trouble.
Fertilizer burn shows crispy, browning edges with a possible salt crust on the soil. A nutrient deficiency shows soft, even yellowing across whole leaves and needs more food, not less. Read the pattern before you feed again.
That difference matters because the two problems need opposite fixes. A hungry plant turns a soft, even yellow across the whole leaf and wants more of a nutrient. A burned plant has crisp edges and a salt crust, and wants less food and more water. Feed a burned plant and you make the damage worse.
To fix fertilizer burn, flush the pot with plenty of plain water. Run water through the soil slowly and let it drain out the bottom three or four times in a row. Use about two to four times the pot's volume in water so the salts wash through and out. Make sure the pot has open drain holes, because water that pools at the bottom just holds the salts in place. Stop feeding while the plant recovers, which can take a few weeks.
Once your plant bounces back, feed at the label rate or even a bit lighter. I now mix my citrus feed at half strength and have not burned a plant since. The biggest mistake you can make is feeding a struggling plant more, hoping food will perk it up. A weak plant often has root trouble, and extra salts only add to the strain. Less is safer than more when you are not sure what your plant needs.
Trim the crispy brown edges if you want your plant to look tidy, but leave the rest of each leaf in place so it can still gather light for you. Keep an eye on the new growth that comes in after your flush. Green, healthy new leaves are your sign that the salt problem is gone and your plant is back on track. If new leaves still come in scorched, flush again and check your pot drains freely.
Read the full article: Yellow Leaves on Plants: Causes and Fixes
