Many "regular" darlingtonia variants can turn reddish with the right conditions, but they're not as easy to color up compared to the genetically red variants.
Outdoors, Darlingtonia typically reach their best color potential during the fall/early winter. Very cool days with intense, bright light all day, coupled with cool nights brings out the best coloration, but as mentioned earlier, these can turn solid red even with part shade! During the winter dormancy period, this variant can turn dark purplish to almost black, but it's not easy to get that coloration: they need absolute full sun all day.
With bright, intense lighting (ie. in a greenhouse or under grow lights) these can color up to their fullest potential, even during the spring and summer. That said, it's not uncommon for this variant to look like a regular form during the growing season if it's not given precise optimal conditions to color up all the way.
These are not beginner plants and are only recommended for experienced growers who have cool, highland conditions plus the ability to give these a winter dormancy period. Cool nights are also key to growing these plants: if it drops into the 50's to low 60's at night, that's what Darlingtonia want!
A very airy substrate (pumice, lava rock, long-fibered sphagnum) is ideal to grow these. Soil temperatures should be kept cool during the growing season (55-75F is ideal), as these plants are very sensitive to warm soil temperatures. That said, if the water is constantly running and the substrate is very airy (ie. almost hydroponic), the roots have been observed to tolerate up to 86F soil temps! The bigger the plant, the more sensitive they are to warm soil temperatures.
Plants offered originated from vitro cultures and have been fully hardened off. They're currently growing outdoors under 75% shade cloth, and get bright indirect light all day long. They are small plants with 2-3 adult pitchers (minimum), are very healthy and have great growth momentum. It was an enormous challenge to propagate these, and this may be the only chance you get at these plants, so if you like what you see, don't miss this great opportunity!