ive also heard that you shouldnt use the plant spikes because they are slow release and can mess with your other fertilizers. plus someone once said that contact with the roots when they grow into them can cause root burn. ive used them outdoors before but since reading this i havnt used them at all. just something else to make your life a little easier. lol i suppose if you grew the plants better than the other people did you might make them a little better, but just as likely they will come out about the same.