A garage would be a very tough place for freshly rooted cuttings to winter and if that is your situation you have a good point. When I order a new salvia I like to have it arrive in March so it can be grown out a bit and propagated so more plants are available for planting in May. You could also reserve a few spring cuttings in largish pots all season and try them as mature specimens in the garage.

Different Salvias require different conditions over winter regarding both temperature and light. What is the light level in your garage? Most late summer cuttings are usually in leaf over winter and need adequate light.

Jim

I used to live in Baltimore, which is around USDA Zone 6, unless you are in the hills to the northwest. If you are in the inner city or near the water, like Annapolis, you may squeak into Zone 7.

I'd take cuttings earlier in the summer, and get them into around 3.5 inch pots, preferably somewhat potbound, to avoid drowning them in kindness. They generally like it dry, and 40 degrees is a good root zone temperature. Can you move them out in something like a Red Flyer wagon for the winter warm spells? Perhaps your yard has space for a small cold frame.

I take cuttings in the Spring/Summer. I get a good rooting average and the plants have all summer and Fall to make a good root system to be planted out in late Winter/early Spring.

When I get small plants (in the mail) I always plant them in 1 gallon cans to develope a root system that will survive our Summer. I got some plants in March, potted them up and just put them out last week. Others I've had growing all Winter. If I just put the little guys in the ground straight away they'll always die.