How to Grow a Bean Plant in a Cup

Growing a bean (​Phaseolus​ ​vulgaris​) in a transparent cup is a great way to teach children about germination, the life cycle of plants, and gardening in general. This science experiment is not only simple, but it's also a great way to get a head start on your garden since you can transplant the bean seedling outside once the weather is right and grow your own fresh beans. Just about all beans can be grown in this manner, and lima, broad, kidney, and pinto beans are all popular choices. That said, it's best to use beans from a seed pack or from a friend's or neighbor's garden since dried beans sold in grocery stores may not germinate properly.

Before planting, seeds need to soak in water overnight to help them soften and sprout. The next day, fold a paper towel in half, dampen it with water, and squeeze out the excess moisture. Set the paper towel in the bottom of a clear cup and then moisten a second paper towel, squeeze out the excess liquid, scrunch it up, and set it in the cup on top of the first towel to fill in the center of the cup.

Slide a few beans along the inside edge of the cup so they are supported by the paper towels and can be seen on the outside of the cup. Make sure to keep the seed a little above the bottom of the cup to give the roots space to grow. Cover the top of the cup with plastic wrap to keep moisture inside and then place the cup in a sunny spot. Check that the towels are still damp every day.

After a few days, the beans should start developing roots when the moisture and temperature around the seeds tell them the conditions are right to grow. This process is known as germination. While paper towels and clear cups are great for showing kids the germination process, plants need soil for nutrients, so it's important to carefully transplant the seedlings into soil soon after their roots begin to grow.

If you want to plant your beans outside eventually, one easy way to do so is to move your seedlings to biodegradable peat pots, which you can plant directly in the ground. Simply add moistened potting soil to your peat pots and then use your fingers to make holes in the soil of your pots as deep as the length of the seedlings. Use tweezers to carefully grasp the tops of the seedlings. If the roots have grown through the paper towel, gently rip the towel until the roots are free and move the seedlings from their cups into the holes in the pots, taking care not to damage the roots and shoots; then gently fill each hole with soil. If your plants have already developed true leaves, these should stay above the soil surface.

Spray the plants with a little water every day and watch them as they grow taller. You can take pictures with a ruler to measure their daily growth. Eventually, true leaves will appear if they haven't already, and when it's warm enough for your seedlings to go outside, it's an easy matter to plant them, peat pots and all, in your garden.