You should be aware that moving them into sun unless they're acclimated to it can set the stage for varying degrees of photo-oxidation (sunburn), depending on what levels of chlorophyll the leaves contain. You can't take a plant that has grown in low light conditions and move it to high light w/o consequence.

When a plant is growing in good light (like at the nursery), it can tolerate fairly high concentrations of fertilizer in the soil/nutrient solution. When you move the plant to low light, the plant can suddenly show symptoms of fertilizer burn - even if you have added no additional fertilizer. If you HAVE added fertilizer, it would exacerbate the problem.

It is most likely you love your new charges so much you're over-nurturing/watering them. They like to be allowed to become fairly dry before the next thorough saturation. The drought response you're likely seeing can come from either over or under-watering. The root-rot that accompanies the over-watering makes it impossible for the tree to remain hydrated, even under normal conditions. I would suggest that you unpot the tree & inspect the root mass for dark, sour or acrid smelling roots. If you find them, you'll need to cut back the roots to viable tissue, repot, place the plants in bright shade, and control the want to water except when appropriate.

Al

I grow and propagate Lantana but do not consider it a houseplant. It is a full sun plant that blooms over a long season and dies back during the winter here, in zone 9. If you are going to keep it in a container, you will need to be sure it does not fill the container with roots and become root bound. When you do water give it enough that the water drains freely from the bottom, then don't water again until a finger inserted in the soil indicates it is dry. Your post does not indicate your planting zone so information cannot be too specific. Al

I am amazed you can hurt a Lantana. They pop up here like crab grass -- and are harder to kill.

I have one that keeps sending up plants after I repeatedly have dug up all visible foliage and roots. And I then sprayed it with Round Up. Repeatedly. So far the Lantana is winning.

I do have one Lantana in a container that is a fushia color that I can't resist because of the color. It is in a container,(I learned that lesson) and it overwintered in the container, died back in the winter then sprouted again in the spring. I am in zone 7b-8, and things that like heat grow pretty well here.

I agree with Al that your zone would help us know what might help with your lantana.

Kay