Should my plants be spiking?

[Suzanne17]

I have 6 or 7 plants in this genera, and they are all in active growth with good roots, bulbs, and lots of leaves. They are on south facing windowsills with a sheer curtain. But I'm not seeing any spikes. I grow them in repotme's oncidium imperial mix (small orchiata Monterey pine bark, Turface MVP, small granite chips, small black lava rock) and they have about a tablespoon of Osmocote as well. I unfortunately underwater them, though. Is that what's holding back spikes? I'm so busy during the week that I forget to give them water so they get a good dousing on Sundays.