Nope mine stay around 78. I have HIGH light 4.7 wpg and pressurized Co2 in the tank they are in. They are sort of mid ground and aren't particularly shaded. I have other stems that I have to trim weekly to keep up with the growth. They are green and lush. I love their look and they are probably the easiest stem I have had. Put them in the 55 at least 2 months ago. when they were about 6"s tall and I haven't had to trim them yet. Wish I did because I would love to trim and plant some new ones, lol. They are about 10" tall now so 4"s growth since planting or about 1/2'' a week. For me that is slow growth. When I get home from work I will have to see if they are really only about 10" now. With 3" of substrate that would put them 7"s from the top of the 55. I may be a little off with that. But other stems I planted at the same time are getting weekly or every other week trimmings.