Does crowding affect plants?

Purpose: To determine the effects of growing plants close together vs. growing plants farther apart.

Materials: Six medium-sized pots, 10 bean seeds, potting soil, water, ruler, large measuring cup, desk lamp, pencil.

Procedure: Fill all pots with an equal amount of potting soil. Be sure that the soil has been dampened with water. Using a pencil, make five holes about 2 centimeters (cm) deep in the soil of one pot. Place seeds in each hole making sure that they are spaced relatively close but equal distance from each other within the pot. Place the remaining five seeds, one in each of the remaining five pots, about 2 cm deep. Cover the seeds with soil. Place all the pots underneath a large desk lamp so that each pot receives full light. Be sure to water each plant as needed. The seeds will germinate in about 7 days, and you will be able to begin making stem measurements. Take measurements for 14 days. Note the difference in stem length for each plant and write down your observations.

Think About This:

1. Which set of plants had the longest stem length?

2. How does crowding affect plants?


USDA-ARS. Does Crowding Affect Plants?. June 2009.

Return to: Ways to boss around a plant – experiments for middle schoolers


Krisanna Machtmes, LSU AgCenter