Seed Germination Test (page 2)

By doing a seed germination test you can make sure that you have good, viable seeds that will sprout and grow. If you can, buy or borrow petri dishes, which are designed for culturing seeds and other organisms. If you don't have petri dishes, you can use two ordinary saucers that have smooth edges.

Use a piece of paper towel cut to a size that covers the bottom of the dish. Moisten the paper towel, then scatter around it a precise number of seeds, for example, 25 or 50. Take another piece of paper towel, cut it to size, moisten it, and use it to cover the seeds. If you are using saucers, turn one of them upside down and place it over the other one.

Keep the seeds at room temperature for a few days. You want the seeds to be kept moist but not covered by water, so moisten both the top and bottom papers periodically. Look at the seeds each day until all the seeds that are going to sprout have sprouted (not all seeds will germinate). Then count the seeds that have germinated and figure out the percentage of sprouted to unsprouted seeds.

Use that percentage to decide how many seeds to plant in your main experiment. For example: If you want to grow 50 plants in your main experiment and the germination test shows that 70 percent sprouted, then divide 50 by 0.70 (or 70 percent). That works out to be 71 seeds that you need to plant in each planter in order to get about 50 good plants in each.

Now for the main experiment. Remove the same amount of soil from each filled planter, enough to cover the seeds to a depth of about 1 centimeter. Scatter the seeds over the soil, then cover them with about 1 centimeter of the soil you removed. Carefully water the soil, trying to keep it evenly moist, especially during this period of seed germination. Use equal amounts of water for each planter.

Now, how do you decide which planter is "experimental" and which is "control"? The goal here is not to let your biases enter into your choice. An easy way to decide is to toss a coin: Heads, planter A is the experimental and planter B the control. Tails, planter B is the experimental and planter A the control.

Now you are ready to go ahead with your experiment, using whatever factor you are testing as the independent variable—a fertilizer element in the experimental planter, a difference in the lighting, in temperature, or whatever you decide you want to test.

During the seed germination test, of course, you should be keeping very detailed records of everything you do.