General Gardening Question

General Gardening Question

So after the winter we had down here, a lot of the more tropical trees either died outright or died way back. There is a house not far from me with an elderly Vietnamese couple filled with Sugar Apples that took a hit in the frost. The trees have been trimmed way back (from about 10' tall to about 4') and the ends of each trunk wrapped in a clear plastic bag, rubber-banded to trunk. What, exactly, is the purpose of the bags? Is it to accelerate growth? Keep bugs from entering the trunk? I tried to ask the couple, but their English is not that great and I came away more confused than ever. Does anyone know?
ID’s

ID’s

grapevine

grapevine

What’s wrong with my gardenia?

What’s wrong with my gardenia?

Photos of my garden. What to plant next?

Photos of my garden. What to plant next?

My first garden.

My first garden.

Bugs!

Bugs!