growing medium: to provide support and a source of water and nutrients
humidity: to keep the plant from losing water by evaporation
Carbon dioxide: to increase the rate of photosynthesis it might be possible to change the concentration available to plants.
water: to help transport nutrients around the plant and to keep the plant from wilting
temperature: to promote growth, but too high temperature can result in the plant losing too much water through evaporation faster than it can produce which will cause the plant to wilt and even die
nutrients: used in the production of lipids and proteins essential for the plants life processes