I've read the answers to two similar questions but as the answers were opposing, i couldn't be sure what action to take. Here is what I have:
Here (Figure 1) is my Avocado plant, which i had potted with no leaves (it had rooted in water), 1.5 month ago.
Brown spots started to occur on the oldest leaves and now they are spreading through the younger ones. Here are some photos of the brown leaves.
Now I will give information about the other conditions of the plant.
The soil I use seems me a little strange but the seller had told me that she also planted an avocado with this soil. It looks a little reddish, and it is a light media. You can see the soil below.
It has some white, salt like things in it, probably the minerals.
Here is the information on the soil package.
It is in a clay pot (but dyed), with a single hole at the bottom. I had also put some stones at the bottom for drainage.
I water the plant rarely, when the soil dries like 3-5 cm, or, when the leaves bends slightly.
It stands near a north-east facing window.
I couldn't decide if the cause is too much fertilized or poor fertilized soil.
Waiting for your suggestions, thank you :)
Edit: 15.03.2019,
It's getting worse. Vermicompost and changing to a normal soil didn't work. I had also taken the plant to the south-east window for more sunlight.