There are several different cultivars of Stellar Pelargoniums generally they are easy to grow and maintain. I would try and keep your plant in good light but not direct sunlight, moist, but not wet, in a dry atmosphere.
If you can borrow Faye Brawner's book "Geraniums The Complete Encyclopedia" you will find a great deal of information about stellar and othe types of pelargonims. If you look at the post by misterg on this forum entitled Geranium ID you will see a photograph of on of the most populars stellars Vancouver Centennial.
Good Luck
Ron

Thank you Ron. To my delight, I noticed life today. Will keep it dryer. The plant is in my greenhouse now, which is covered with a 50% shade cloth, so it should be ok. Maybe it just needed warmer temps.

I just noticed your post and advice to keep the geranium in a dry place, Ron. Perhaps the humidity in my greenhouse was too high. I will take the plant out pronto!
Night time temps are still in mid 40s. Is that too cold for the little Stellar? I could have it under the eaves there.

Night time temps of mid forties Fahrenheit might not kill your plant but it is unlikely to thrive. Can you find a well lit window-sill in the house where the night temperature remains a bit higher?

Thank you melrt968. I will bring the Stellar into the house.