Three of the most important are nitrogen, potassium and phosphorus. Plants grow best with the right balance and concentration of nutrients. Commercial fertilizers vary in the amounts of these essential nutrients that they provide. Also, different plant species have different nutritional requirements. Plants will grow best in a certain temperature and humidity range, which can vary with the species of plant.
Plants grown in chambers often deplete available carbon dioxide, which can limit their growth.
Ventilation and air circulation mixes the air and makes carbon dioxide available for plants.