Greenhouse vegetable plants may end up growing faster and stronger than those grown in a traditional garden, because you will be giving them the ideal environment for growth. When it’s below freezing outside, passive solar collectors and small heaters can leave the interior of a greenhouse cool but perfectly liveable for most spring vegetables. In the heat of the summer, fans and other cooling units can protect tender plants from the scorching heat of a southern climate. You can grow greenhouse vegetable plants directly in the soil inside the enclosure, but container gardening is a more efficient use of space. You can take advantage of all three dimensions by placing planters on shelves, using trellis systems for vine plants and hanging planters for smaller vines, such as cherry tomatoes and strawberries.