Welcome to the orchids forum,
@fwolfyusc17
Can you tell us a bit more about your Cyms? Even if you don't know the name, some photos of the plants and the blooms (when they have previously flowered) would be most helpful.
Bill is correct that most Cymbidiums cannot be grown as houseplants. They need good light to grow well and flower.
The temperature range required very much depends on the species or hybrid.
Many of the traditional hybrids (think most of the showy intermediates and standards over the last century of breeding that flower in late autumn through spring) need that diurnal variation (day vs. night difference) of at least 10°C to initiate flower spikes. My understanding is that that variation is far more important than the actual nighttime temperature. They don't like excessive heat (above about 86F), although they can easily tolerate up to 35C/95F with the appropriate care. Likewise, they will often tolerate a light frost, although may show signs of damage on the leaves (ideally you want to protect them once it gets close to freezing, i.e. below 40F).
The "Chinese Cymbidiums" (really, these are hybrids with the smaller "heat-tolerant" species from the Jensoa section of the genus) have different requirements. They dislike temperatures below around 10C/50F and will handle temperatures around 30-35C/86-95F without much trouble. There is
less (but not completely absent) need for a diurnal variation to make them flower. Hybrids with
ensifolium in particular can often be prompted to spike simply by moving them from a warmer to a cooler spot on your property for a few weeks. In their case I think it has more to do with the change in average temperature than the diurnal variation.
Most Cymbidiums need as much light as you can give them (without burning the foliage). This means the leaves should be a bright or light green (not yellow or starting to develop brown sunburn areas). Dark green foliage usually indicates insufficient light. Some species and their hybrids need more light than others, but generally there are very few Cyms that do well with the lower light levels that would typically be fine for Phals or other orchids often grown indoors. I suspect that you could give them a lot of sun in your location in spring and autumn, reducing to just a few hours of morning sun in summer (since your average temps seem to be about 5°C cooler than mine).
Watering is also important, as Bill mentioned. There are exceptions to the rule, of course (like not watering
Cym. canaliculatum or its hybrids through winter, and similarly providing
insigne minimal water in winter), but typically they like to be kept moist (but not sodden) in the growing season. The amount of watering needed entirely depends on what media they are in. Very open mixtures (like Orchiata bark) will need more frequent watering, whereas moisture-retentive mixes (e.g. more than 25% coir or spaghnum moss) will need much much less to avoid the risk of root rot. If your plants haven't been repotted in years, you may find the media has broken down too much and they do not have a healthy root system (which will also affect flowering).
I hope that helps! Let us know if you have any questions.
