Lots of helpful advice but the OP has not come back.
Now that is what I call rude.
But I think the lemon is dead and unsaveable from any advice. Â
My supplier, The Citrus Centre, say: Almost no water in the winter - if I do that the leaves drop off.  Keep in the light - after this winter it would be dead in unheated my greenhouse (min so far -4ºC).  I tried one winter in the greenhouse and it took a year to recover.  It's now in a ±45cm pot, in my quite light garage, min +10ºC, watered with ca 1 litre of fertiliser-added rain water on Sundays.  Some leaves are dropping.  I also suspect the poster's lemon  may have been overcropped the first year.
 location: Surrey Hills, England, cretaceous acidic sand. "Have nothing in your garden that you don't know to be useful, or believe to be beautiful."
Lots of helpful advice but the OP has not come back.
Now that is what I call rude.
Huh? Normally when people ask for advice they come back and say 'thank you' or respond in one way or another. Some people spend a lot of time answering questions and drawing on their experience to do so. So....you could say the OP is being rude......Â
Based in Sussex, I garden to encourage as many birds to my garden as possible.
Posts
Now that is what I call rude.
But I think the lemon is dead and unsaveable from any advice. Â
My supplier, The Citrus Centre, say:
Almost no water in the winter - if I do that the leaves drop off. Â
Keep in the light - after this winter it would be dead in unheated my greenhouse (min so far -4ºC).  I tried one winter in the greenhouse and it took a year to recover. Â
It's now in a ±45cm pot, in my quite light garage, min +10ºC, watered with ca 1 litre of fertiliser-added rain water on Sundays.  Some leaves are dropping.
 I also suspect the poster's lemon  may have been overcropped the first year.
"Have nothing in your garden that you don't know to be useful, or believe to be beautiful."
The OP may be sick.