hello all,this winter my succulents and cacti are in a plant room instead of the warm suth facing shed with big windows they had been in each winter.now the plant room has two solar tubes in ceiling,an east facing window and a west facing sliding door.all my plants are as close to the west facing door as possible,however ive noticed some plants are not doing as well,they recieve about 4 hours of sunlight daily,is this enough for them?these plants share the room with about 60 other plants of varous sizes and all are doing well.any info or help you give will be greatly appreciated.thanks!