When we think of greenhouses, most of us think of hulking, ship-like monoliths made of plastic or plexi-glass.  But greenhouses can be small, too. Small enough to fit in your back yard, in fact. Or even in the palm of your hand.

A greenhouse, as defined by Merriam-Webster, is “a structure enclosed (as by glass) and used for the cultivation or protection of tender plants.” Greenhouses allow for more control over the growing environment of plants. Temperature, sunlight levels, fertilizer and water amounts, can all be regulated. Plants are protected against the worst of the elements, extending the growing season. And while most greenhouses are large, there’s no hard and fast rule where size is concerned.  Below are five examples of truly mini greenhouses!

1. Two liter soda bottle

What could be simpler? Or littler? Simply remove the top and the label from an (empty!) soda, juice, or water bottle; and turn upside down! Can be used directly on the ground, or around a small planter.

2. Plastic salad-greens container

How ironic! A product that once held greens being used to grow… greens. But anyway. The picture pretty much says it all, but for those of you who prefer narration: fill bottom of container with topsoil and seeds, and cover with either lid or another container. Check out this video for another take on this easy garden hack.

3. Used Windows

My personal favorite! Brace four old windows together, using a fifth window as a lid. The base can be made from an old pallet or crate, or even a simple raised bed. A superbly effective way of not only extending your growing season, but keeping those old windows out of a landfill.

4. Aquarium

Look how happy that couple is with their aquarium greenhouse! Simply take your old unused aquarium greenhouse, turn it over, and, voila: instant greenhouse!

5. Milk Crate and Comforter Bag

If you’re like me, you saved the plastic bag that your comforter came in, thinking you would use it to store your comforter come summertime. But you’re not that kind of person, which is good news, because now you have a perfectly good excuse to build a very cool mini-greenhouse. Just get an old milk crate and place it inside the comforter bag! You’ll be sprouting seeds in no time!