The tallest is about 3 inches high. I have a one of those bottle gardens which I'm not using and decided to try to create a cactus garden in it.
I'm found out the best compost to use... 2 parts john innes #2 plus one part horticultural grit. Maybe they won't die on me! I've been very unlucky with plants since I moved into this appartment... I don't have any windowsills in my living room and the light was obstructed by the tree outside, but since they've removed it I want to see if anything will grow now.