Miniature greenhouses offer a way for gardeners to grow tender plant species, as well as a way to keep humidity up to aid in rooting cuttings and germinating seeds. This enclosed space keeps the soil moist, cutting watering to a minimum. Small greenhouses, just like their large counterparts, can present growers with big challenges. Experienced greenhouse growers share many tips and tricks of the trade in books, gardening clubs, magazines and Internet articles.
Avoid Full Sun
Due to their small size, miniature greenhouses overheat quickly. Too high temperatures for even a short amount of time harm some plant species. Covering the greenhouse with a shade cloth during times when the sun is the strongest will help control a heat spike. For greenhouses made of mason jars or smaller containers, place away from direct light.
Add Air Circulation
For the smallest greenhouses, like those made for tabletops, providing air circulation is, at times, problematic. The use of miniature battery-operated fans, like those made for waving in front of your face, will push air around the plants without disturbing them. The simplest method is propping the lid of the container open for several minutes a day and then aiming the fan across the plants.
When using a miniature greenhouse, avoid over-watering your plants. Many of these greenhouses have solid bottoms without drainage, and the excess water does not drain off. Too much water-laden air mixed with very high temperatures can cause fungus and other problems on plants. Water only as much as each plant needs---and remember that greenhouses trap moisture. so the soil will require less water, less often.