I just bought an avocado tree about 3 weeks ago. At first, it was dropping leaves like crazy. I put it in a 25 gallon pot. I did not want to overwater it. I watered it when I put it in the pot, then 4 days later I watered it again. I figured I was overwatering it, so I did it in 6 days. Some of the leaves are brown at the end. I put it under the trees so it does not get over heated. How often should I water it? What does it mean when the end of the leaves are brown?
This indicates a watering issue. Either the tree is not getting enough water or there is something affecting the roots that is preventing the roots from taking up water. Check for root rot: https://www.gardeningknowhow.com/plant-problems/disease/treating-root-rot-gardening-tips-for-housplants.htm
If you don't find root rot, increase water to the tree. Plants in containers outdoors should be watered at least once a day, twice when temps are over 85 F. This article will help with watering: https://www.gardeningknowhow.com/special/containers/container-plant-watering.htm