Do these plants come back every year? They look very dead, and I'm not sure if I should have cut them down before winter.
Rain daisy (botanical name Dimorphotheca) is an annual, so the plants won't come back every year (the winter kills them). You can cut them down to improve your garden's appearance, but it's not required.
what would keep rain lilies from blooming?
Try fertilizing it with a phosphorus rich fertilizer or bloom booster. This article may help
https://www.gardeningknowhow.com/ornamental/bulbs/rain-lily/growing-rain-lilies.htm
Why my Rain lilies are not blooming. Have had for 3 years and no blooms this year.
The soil may be depleted of nutrients. If you have not, try fertilizing the plants with a fertilizer for flowering plants, such as miracle grow or Osmocote. This article may help
https://www.gardeningknowhow.com/ornamental/bulbs/rain-lily/growing-rain-lilies.htm
Hi. I live at India where the temperature hovers around 30-40C almost everyday! Recently I had bought a pink Zephyranthes from a nursery. I wanted to transplant them to the pots. But they have developed very long roots that it's difficult to plant them in a bowl like container. I fear that they would die because of very less space for their roots to grow. Is it advisable to prune the roots?? I don't have any big sized pot right now. Thanks in advance.
You could trim 1/3 of the roots from the bulbs.
https://www.gardeningknowhow.com/ornamental/bulbs/rain-lily/growing-rain-lilies.htm
When to plant Zephytanthus Robustsa bulbs Common name Fairy Lilly
It will be best to plant these in Spring, after the soil warms up some. They are sensitive to freezing temperatures, so it is best to make sure that they are not exposed to them for long.
This article will help: https://www.gardeningknowhow.com/ornamental/bulbs/rain-lily/growing-rain-lilies.htm
Want to separate Rain Lily bulbs.
The best time to divide or move Rain Lilies is in the fall in the Lower South or early spring in the Upper South, because that's when the bulbs are in active growth and you can find them.
https://www.gardeningknowhow.com/ornamental/bulbs/rain-lily/growing-rain-lilies.htm