I was wondering, starting my own garden and having my coriander plant go to seed in winter and seeing locally grown coriander for sale at the grocer's at the same time. How do they grow coriander while mine has gone to seed? I thought the temperature and the amount of light determined when a plant went to seed, but then couldn't you keep a coriander plant outside in spring and summer during the long hours of sunshine and keep it in a greenhouse over winter with artificial controlled temperature and light? If this is the case, how long could a plant live for in this situation and does that mean that it is possible to have a year-round supply of coriander? Am I right or is the plant genetically programmed to have a certain lifespan? I'm not really a gardener, I just enjoy cooking and have a few edible plants growing around the house and this question has been on my mind for some time.