i bought a plastic green house for the young un to mess about with, just a cheap one from a local garden center, it has 4 shelves in it with a sip up door on front, the problem ive had is that i had four tomato plants in it that have got to around a mtr high but 2 of them have died of, theyve had plenty of water (twice daily) plus tomato feed, ive also other plants in there, chillis, cucumber ,lettuce and strawberry's, have i got too much in it and how often should i have the sip up door open as it does steam up alot, or is it some disease the plant might have, any advice would be appreciated,