I've been growing a couple of avocado trees from pits and one of them is really struggling.
It got a spider mite infestation, which I seem to have controlled by washing the leaves with a very dilute dish soap mixture every few days for a couple weeks. Since then, the leaves developed slight browning on the tips, which I wasn't concerned about, but now the browning is spreading to the leaf edges.
Some of the browning has very clearly defined edges, similar to the brown tips:
Another leaf has very indistinct edges to the brown spots, which makes me think it might be a different thing causing it?
The tip of the growth bud has also shown browning and, I realized this morning, the very tip of it has broken off. It has been a while since this plant has had any real growth.
I'm in Los Angeles and this plant mostly lives indoors in a very sunny room. It doesn't get direct sunlight, but it does have a grow light. It is potted in a cloth pot with well-draining succulent soil. I water it when the top inch or so of soil gets dry to the touch (usually every 1-2 weeks). I'll totally drench the soil until it is running out everywhere.
I have two other avocados that have received identical treatment and show none of these problems. The one on the left got a bit sunburned when it was younger, thus the scorched leaf you can see. After this, and a fourth tree getting eaten by a squirrel, I moved them inside.
Is there anything I can do to save the struggling plant?