Indoor gardens can take many forms. In one garden I designed, I filled a large window with parts of old columns retrieved from demolition sites, cut them to different heights and set out a variety of ferns.
By making the size and shape fit your room, a large planter can be used to provide an instant indoor garden. Place four casters -- the strongest you can find -- on the bottom of the planter. Line the inside with heavy gauge film, put down a layer of white stone to reflect light on the bottom of the leaves and retain moisture, and set out your garden in pots. You can rotate or remove a pot and the entire garden can be turned or moved as needed.
Another way to garden indoors is to use hanging egg chairs or baskets. Add a wall-to-wall dowel or chrome shower rod across a recessed window and fill it with baskets of flowering or green plants.
Loop the basket hanger over the rod; if it has no loop or hook, hang the baskets from shower curtain rings. To make the baskets cover more glass, simply extend the length of a few pots by adding sections of chain, rope or hangers.
By far the most ambitious indoor garden is a "reverse" greenhouse you can build into your window. With some access to sun, almost any window will do. I call it "reverse" because the ordinary greenhouse projects outdoors from the window, while this alternative projects indoors.
I built my greenhouse in one of two double windows in the master bedroom. To create an alcove deep enough for a 4-foot-deep greenery, I built out storage units on either side, creating ceiling-to-floor clothes closets for the room -- an unexpected bonus for the homeowner.
I chose a wood-framed greenhouse and painted it dark green as a contrast to the white of the new clothes-closet doors. The floor, carpeted in the same deep green, matches the walls. Inside the greenhouse, I put down a strongly reflective white vinyl surface, which is easy to maintain.
The east-facing window provides welcome rays of early morning sun. In addition, it's an ideal growing environment for all kinds of plants and an unanticipated source of heat for the room.
Lastly, you will want to keep in mind that your plants will need adequate lighting and good air flow in order to grow. If there is not enough light in your space, you will have to invest in a good LED or High Pressure Sodium Lamp.