Lemon tree leaves green but dried and crumbled, HELP!

I have an indoor lemon tree grown from a seed on a whim 6 years ago. It turned into a thriving and beautiful, healthy tree. 1 month ago, the leaves suddenly and inexplicably started drooping and now are curling up and completely dried out. It started with a couple leaves and now the whole tree’s leaves are crunchy and crumble to pieces if touched. I’ve been watering whenever the soil feels dry more than 1 inch down, about once every 3 weeks or so. Leaves are still bright green and branches are green, just the leaves are dead. I fertilize with liquid Miracle Grow every other watering in the winter. He hasn’t been repotted in 4 years.

About 3 months ago, I had him right by the front door due to brighter light options (Southern facing) and realized the cold from the door opening a lot might have adversely affected him. We’re talking -10F weather around here lately. So I moved him back to his usual spot but noticed then some initial “sickeness” in his appearance.

Our tree has been a beloved member of the family, help save Pucker!

 

Welcome to the forums.

The photos look very much like those posted by members in the past of trees damaged during shipment in cold weather. However I would not have expected such damage due to brief moments of exposure from the opening and closing of the door. Perhaps there were other factors on top of the cold. The tree would have required more water at its new location because of the increase in light levels. Perhaps it was under-watered; three weeks is a long time to go without water in a high light location if the tree is actively growing, given the relatively small size of the container.

Since the stems are still alive and green there's a good chance the tree will eventually bounce back. It will need very little moisture as photosynthesis will be much reduced without its leaves. Discontinue fertilization and keep watering to a minimum. Place in a warm, protected spot with high light levels, preferably behind a window with a southern or western exposure.

 

Thank you so much! Yes, I looked at those other threads and gleaned some extra info. I am thinking of repotting him too. Do you think now would be a good or bad time to do that?

 

I'd wait until the tree has had a chance to put on a new set of leaves. That would allow it to rebuild its energy reserves. Repotting and the resulting damage to the root system would be detrimental at this point.