Seeds are the dormant state of a plant's embryo. If you split a seed in half, you will find a tiny plant and a large mass of protein that the plant uses for an initial burst of energy to shoot into the sunlight. Seeds may lay dormant for years before sprouting. And while most seeds will lose their viability in 10 years, scientists have germinated seeds that are thousands of years old, according to "Science Magazine."
Seeds should always be planted in properly prepared soil. The best time to prepare soil for spring planting is in fall. You should first break up the soil with a mattock, spade or a rototiller. While the soil is loose, it is easier to remove debris such as rocks and sticks as well as plant material that can harbor diseases. All soil types can be improved by mixing compost into the loosened soil. Compost improves drainage and aeration in heavy clay and hardpan soils. In sandy soils, compost will improve the nutrient content and help add loam to the soil. Soil broken up in the fall is not subject to erosion. Instead, the repeated freezing and thawing of soil through winter helps to break up clods. Then level the soil and prepare the seed bed for planting. But if you work the soil in spring, it may be wet and subject to compaction.
Seeds that sprout best are typically less than a year old. Older seeds begin to lose their viability the longer they are stored. Seeds stored in dry conditions will remain viable longer than seeds stored under damp conditions. To test older seeds for viability, you can place them in a glass of water for an hour. Seeds that sink to the bottom are still viable, and will sprout if planted. Seeds that float are no longer viable. Scoop floating seeds off of the top of the water and discard them.
Not all seed should be planted at the same time. Various crops are more cold-tolerant than others, and should be planted early. For example, leaf lettuce can be started in early spring for a harvest in early summer. Pumpkin vines should be planted in late spring for a fall harvest. Most seed packets contain information on the best time to plant seed. Cold-tolerant seeds can be planted up to two weeks before the last average frost date for your area. Tender plant seeds can be started indoors early, where frosts and cold won't damage them. These tender transplants can be hardened off once the danger of frost is past by bringing them outdoors for short periods of time. Once transplants are hardened off, you can plant them into the ground.
Seed Planting Depth
Most seed packets specify plant spacing and depth on the seed packets. Where this information is not available, you can calculate the plant depth by measuring the seed at its widest point. Seeds should be planted about twice the depth of their diameter at the widest point. If you plant a seed too deeply, it may still germinate, but the sprout may die before it reaches the surface.