Hi. Is there something I should know about growing cacti outside. I have grown cacti under glass most of my life but only the last 2 years have left any outside. In pots. I have 2 opuntia; humifusa and polycantha. Both produced healthy shoots early this year but most are now new pads and a few shoots dried up. NO flowers. Do flower shoots look different to pad shoots? They are against the south wall of the house.