For us in Fresno indoors, not in a greenhouse, Cattleyas
bloom between April and June. The books that we have
are rather inconsistent on what triggers a blooming spike
or spikes to appear. Is it light reduction or cooler temps
that will facilitate a bloom? I think both factors are equally
important. I have not found for us which factor works best
but I am leaning towards cooler night time temps.
The spike itself starts as a round stem-like protrusion that you
will not mistake for anything other than a blooming spike. On
one of our varieties the flowering spike develops from the tip
of a shoot ending in a whorl of two leaves. The other form of
Cattleya of ours will have its spike initiate from the base of the
For further reading you may want to check out these websites.