Can any one advise me where and when I can buy any Pelargonium Calliope Series in Calgary. I have a greenhouse and would like to purchase small ones in Apr.

We have quite a few members in Calgary. Perhaps @joannabanana or @CarolineScott can help?

If you are looking for smaller than 6" inch pots, then Garden Retreat may be your best option. If you can wait until May, most Garden Centres will have them, including Calgary Co-op, but they will be in a 6" or 1 gallon size. Most wholesale growers will only grow the Calliope series in larger sizes since the cuttings are very expensive. You can google Syngenta flowers to see the plant breeder list of 2014 varieties.

You might get lucky & find some at the Garden Show, Spruce Meadows on April 12 & 13. Some of the vendors sell plants at the show.

Don't know if this will help you in Canada, but down here they are grown by Proven Winners and marketed at Home Depot. Keep checking if you have a local HD near you. If you get them when they first come in, they might be the smaller size pots.

Then before they get zapped next fall, take cuttings of the ones that survived and grow your own over the winter if you can.