The sun may be out and you may be sweating like a furniture mover, but that doesn't mean it's the right time to plant your new garden. A horticulture specialist in Penn State's College of Agricultural Sciences says the key to sprouting vegetable seeds is soil temperature. This is the lowest temperature at which germination happens. At this temperature, the seed will take longer to germinate, exposing it to rot and other damage. Nuss says home gardeners can start plants indoors, although some plants do not transplant well and are better sown directly into the garden when soil temperatures are correct.
Ambitious gardeners can force soil temperatures higher by using plastic.
The soil should be covered with black plastic and overlaid with wood strips. A layer of clear plastic is then placed over the wood strips. The air space between will insulate and reduce heat loss. Nuss recommends buying a good soil thermometer to determine when seeds can be planted. Also, the best temperature for germination may be markedly different than the optimum temperature for seedling growth.