Oncidium spiking
 

I live in New New Hampshire and I (12) different orchids, all blooming
very nicely. But I have a Oncidium that just 'grows' and never
spikes.

I tried everything from plenty of water & fertilizer, to putting in
the garage
to get the temperture changes, put it in the basement with little
light and cool area, I placed a grow light on it at night with plenty
of sun during the day, etc. Nothing, no spikes, just keep producing
more bulbs.

Since I have purchased the orchid (3) years ago it has doubled in
size, (9) bulbs 2" wide by 3" tall, and looks great, just can't get
spikes.

How to get the plant to spike?...

TIA