What does the article mainly discuss?

A: You know, I love these container gardening and I think it is especially adapted to contemporary living. Plants in containers display great variety of form and texture. They can be used to create instant indoor gardens;
they can be moved from one home to another; and they can be moved outdoors in the summer and indoors
during the cooler months.
B: Woo, that’s wonderful. Besides the space is not a problem. Container gardening can be conducted in a single pot on a table or windowsill, in a more elaborate room divider, or in a built-in planter.
A: But there are so many kinds of containers and I have no ideas how to chose from them, you know, there are common clay pot to cans ,jars, boxes, baskets and tubs.
B: I hear most people select containers for both their practical and esthetic qualities. These include cost, availability, weight, strength, durability, attractiveness, and decorative and sentimental value. What’s more, the size and shape of the container should be consistent with the plant’s size and shape. Tail, tapering plants are more attractive in tall, relatively narrow containers. Short, compact plants appear more at home in shallow wide containers.
A: Yes, you are right. And I think those containers must have those holes in the bottom for removal of excess water are best. Water-tight containers arc difficult’ to manage; excess water will accumulate at the bottom of the container and injure plant roots by excluding oxygen.
B: Those are the fundamental requirements for plant growth, but plants need light, water, nutrients and a satisfactory temperature range.
A: Yes, light is the most critical requirement. The levels of all the other requirements are adjusted in relation to the amount of light that plants receive. When plants don’t have enough light, they grow slowly and become tall and thin; it becomes difficult to avoid over-watering them. Plants are easier to maintain in good condition when their light requirements are met.