We have a large avocado plant (indoors) that is mystifying us. A couple months ago, it shed most of its leaves. The leaf would get droopy and the tips of the leaves would turn brown and dry out and then spread up the leaf. It got down to its last seven leaves and then seemed to stop, although all of these leaves have varying degrees of this leaf tip burn. Now over the last month or more, small new growth is appearing. They have not grown much at all and are only about an eighth of an inch long.
When growing an avocado (Persea species) indoors, you will need to be sure it is getting enough light. It is normal for the plant to drop older leaves. You should also keep the plant in a cool spot. According to The Houseplant Expert by D. G. Hessayon (Expert Books, 2001), your plant will do best if you repot it annually and pinch the tips to encourage bushy growth. Lee Reich discusses growing avocados indoors in an article (now archived) for California Rare Fruit Growers. Here is an excerpt:
“Indoors, avocado plants are often gangly and sparse with leaves. One reason for the plant’s gawky appearance indoors is light. Lack of sufficient light causes stems to stretch for it. Another reason is that avocados shed many buds along their stems, buds that might have grown into side branches. The result is a plant stretching out for light, sending out new growth mostly from the tips of the branches and shedding old leaves.
There are several things indoor gardeners can do to keep their plants more attractive. Most obvious is to give an avocado tree bright light. Also, the stretch for light is exaggerated when warmth stimulates growth, so the ideal spot for the plant is at the brightest window in the coolest room. Beyond that pruning back a stem or pinching out its growing tip stimulates branching by awaking dormant buds (not all are shed) further down the stem. There is nothing that can be done about the shedding of older leaves.”
Grown outdoors in an agricultural setting, avocado plants sometimes get leaf tip burn from salt accumulation, as this article from California Rare Fruit Growers explains. If you are using especially salty tap water or overfertilizing your plant, that might be causing the burnt leaf tips. Other causes could be lack of water, too frequent light watering, or poorly draining soil.