How do you undo effects of over fertilization in a lemon tree? My tree looks very sick, has burnt brown edges, brown spots that seems to be increasing by the day, dull splotchy looking leaves, and are falling off to the touch. Tree had some form of granular fertilizer when I bought it, but a month later I added some more, but in a very reduced amount. It was slow release, citrus specific and seems to have dissolved already. I added a few cups of water to try to get rid of nutrients and changed top layer of soil a few days ago, but not many results. Branches are looking very bare due to leaf loss. The picture shows leaves that have already fallen off.
Thank you for contacting the Toronto Master Gardeners. It seems that it’s been quite challenging to get your Meyer lemon tree well established and healthy !
When there is excessive fertilizer in the soil, the salts in the fertilizer will draw moisture from the roots, resulting in plant dehydration that causes leaves to turn brown and crisp along the margin. It sounds like you have taken the right steps to correct possibly over fertilizing. As a rule of thumb fertilization should be done during active growth. I suggest that you not fertilize until your plant has stabilized. There are simple soil test kits that are widely available and will test pH, nitrogen, phosphorus and potassium levels that might be helpful.
Overall I think your plant has been stressed by the extreme heat we have had recently, by the direct sun it has been exposed to after being indoors, and by the moves back and forth from inside to outside. I think it will benefit from being in a stable environment, whether indoors or out during the summer months. If it’s outside choose a spot that gets morning sun then shade in the afternoon. When it’s time to move it indoors, make this change gradually.
I think it would also be beneficial to investigate a possible insect infestation for which advice was provided in a previous response.
I will likely be a slow process but I hope your Meyer lemon tree recovers well and flourishes after a bit of a rocky start!