When I was young my mother has successfully grew very delicious green shoots out of small onion bulbs. And that was in the middle of winter in Russian Siberia (56N latitude), when the outside temp was -10F on average. It was just an East facing kitchen window with 8-10 small jars filled with water and with the bulbs on top of them (sometimes over the cardboard down-sizing rings). The windowsill was sitting over the hot water heat radiator, so it was quite cozy microclimate on top of it. Great snack to vodka year-round !