Glads are great to grow in containers on the patio ... but remember to use nice deep pots. The
flower spikes can grow quite tall, and will make a nice screen, but keep them out of areas with strong winds -- they tend to break & topple over.
In terms of overwintering them in the garage, if it's unheated the bulbs will freeze and won't grow back the following year (I'm in a
zone 5 and can attest to this lol). Storing them in the cold room works great, or in the fridge if you'ce got a spare in the basement.