Selecting appropriate seeds for speedy germination is important when time is of the essence---for example, for a science fair project. In order for a seed to germinate, it must absorb a large amount of water through its outer coat. This water absorption activates an enzyme within the seed that leads to the successful germination and growth of the plant.
Radish seeds are some of the fastest-germinating seeds, generally taking between six and eight days to germinate. Because of their small size, however, the seeds can be difficult for smaller hands to work with, and the shoots are not as dramatic as some of the larger options. If you need not only a seed that germinates quickly, but also one that makes for a good show, you may want to opt for one of the other seeds---especially considering that the germination difference is only a few days.
The most common melons used in science projects are watermelons, although other melons including cantaloupe and honeydew work fine as well. Watermelon seeds are generally big enough for little hands to handle with ease, and their shoots are of a moderate size. Germination times generally range from five to 10 days.
Squash seeds are generally sturdy and fairly simple to grow. Germination times range from six to 10 days. Pumpkin seeds are often used, both because they are large and because they are familiar to most children from Halloween.
Beans, especially green beans, are possibly the most commonly used seed for science projects. The seeds of most bean varieties germinate dependably in seven to 10 days and are easily handled by small fingers. Bean seeds, more than most other seed options, look very much like the beans that grow from them, so they also allow children to learn about what seeds are and how plants create them. Beans also produce a good-sized, sturdy shoot that is easy to use if your project includes ongoing observation or analysis of the plant.
Like beans, peas are dependable and look like the product they end up producing. They are sometimes a bit harder to handle than beans, as they roll around easily, but are a good option for most science projects. Peas usually take seven to 10 days to germinate.
Flowers are not often used for science projects, because their seeds are usually very small. If you intend to plant the resulting shoots, though, and do not have the space or desire for a vegetable garden, they can be an excellent option. Marigolds have the shortest germination time at five to seven days. There are also a number of flowers that germinate between seven and 10 days, including zinnia, poppy, morning glory and cosmos.
After selecting the best seeds for your project, you can take a few easy steps to further speed up germination. Gently scratch the surface of the seed (sandpaper is an easy way to do this) and then soak the seed in warm water overnight. This helps speed the necessary water absorption. Once you plant your seeds, be sure to keep them evenly watered and warm to continue the germination process.