Green garlic is immature garlic cloves harvested early in the season before the bulb fully matures. Garlic scapes are the spindly curled shoots that grow above ground, they mature into curly green stalks topped by tightly closed buds. Garlic Greens are the immature top growth that pops up shortly after you plant garlic cloves, if left to grow they become scapes.
If you plant garlic in the Garden in the Fall you'll have harvest-able edible garlic greens within a few weeks. They are used just like scallion greens or chives.
Growing garlic bulbs to full maturity indoors is a tad bothersome and some feel not worth the effort. Garlic greens on the other hand are easily grown indoors and produce rapidly and quickly.
Plant garlic cloves indoors in a suitable container with drainage. Depending on how many cloves you anticipate planting should dictate the container sizes and or the amount of containers. It ain't rocket science as some garden gurus like to pretend just use common sense.
Fill the container with potting soil up to about 1/2 inch from the top of the container. Seperate the garlic bulb into individual cloves and do try to leave the papery peel on, although if a few crumble off it's no big deal.
Some gardeners advocate soaking the cloves in a jar of water containing liquid seaweed and baking soda for a several hours prior to planting. This may be helpful but is not necessary.
Individual cloves should be pushed about an inch into the soil with the pointed end upward, several in each pot. Water then well and leave them on a sunny windowsill or even outdoors if the weather is not abysmally cold. Water daily, making sure that the soil remains moist but not saturated. Green shoots should pop up in about a week and are ready to use when they reach about 8 inches in height.