Orchids are generally seasonal, blooming at the same time each year (roughly). The exception is those Phalaenopsis that you find blooming in the grocery store, hardware store, etc. which are forced into bloom through chilling and are therefore available in bloom all year round. If not forced, most Phalaenopsis would bloom in the Spring through Summer time frame (March-June) [a story for another day]. In any case, if you buy your orchids in bloom and you space your purchases throughout the year, assuming they bloom at the same time the next year, you will typically have something in bloom pretty much all the time! Of course, buying orchids like Phalaenopsis or Cymbidiums with flowers that last a month or more helps as well.
One last tidbit. People complain that they cannot get their Phalaenopsis to re-bloom in the home. Phalaenopsis benefit from a 10 degree drop in the Fall time frame (or really whenever you're trying to force them to bloom). Once the new flower spike starts to emerge, you can return the temperature to something more people friendly. When I lived in "cold country" I used a programmable setback thermostat to drop the temperature by 10 degrees during the day (while I was at work) and raised the temperature back up to the 70's when people were around. The Phalaenopsis would bloom en masse in the Spring. In theory, you could do this at any time of year. However, I did it in the Fall/Winter when I could just turn down the heat during the day. If you wanted to force them into spike when it is warmer, just pop them in front of a swamp cooler or an air conditioning vent for a week or two.
Here are the Fall bloomers from the greenhouse.
Bulbophyllum rothschildianum 'Red Chimney' FCC/AOS
Dendrochilum cobbianum album
Dendrichilum cobbianum (this one with a nice orange lip!)
Laelia anceps 'Mendenhall' X L. anceps 'Newberry Princess'
Stanhopea occulata (this one smells like Andes Mints!)