I grew 4 avocado trees from seed about a month ago, and they were growing really well and were healthy back then. However, I decided to transplant them after seeing how crowded the pot was and moved them to another container. A few days later, their leaves started drooping and now the leaves are becoming really dry. The tops of the plants are also starting to brown. What should I do to help my plants? My plants are about a foot tall, and one of them started to lignify at the bottom.
I am currently growing about 50 avacados from seed and frequently get the problem you describe even from plants that havent been transplanted, I just strip off all the leaves and they grow back. I doubt it's transplant shock, avacados don't mind at all being transplanted, compared to jack fruit and papaya which freak out when you give them a new home
They are in transplant shock. Transplant shock in some case can be a temporary moment of looking very sickly as the get adjusted to their new home. Transplant shock can also be permanent, leading to death. All you can do is make sure they are kept moist, not wet, kept warm, but not by a radiator, kept in bright light, but not direct light. If you can provide these three things your plants might be just fine.
You should be prepared for the fact you might lose one or more of them. Some plants do not transplant well. They just do not like their roots disturbed. (Especially those with tap roots.) Avocado have fibrous roots that live near the surface. These roots need lots of oxygen. If they are planted too deep or in a compacting soil they will suffer. Even if not all the roots are too deep, but most are good, you should expect a negative reaction by the tree. When planting the roots should spread across the top of the soil with just a thin layer of soil covering them. You can plant it deeper if you have adequate drainage. You should have at least 1:1 drainage to brown matter (water holding.) Examples of drainage are perlite, pumice, & scoria. Examples of brown matter are Sphagnum Peat or Coconut Coir Peat. This will provide the roots with air pockets in the soil. Providing the roots with the oxygen they need to survive.