Museum of Science and Industry

Habitat Overcrowding

See what happens when plants compete for survival in an area with limited resources. What survives? How is plant quality affected?

What You'll Need

Potting soil
Four (or more) small milk cartons or pots
Water
Radish seeds
Ruler
Measuring cup

What to Do

Use a measuring cup to fill both containers with the same amount of soil. If using milk containers, punch a few holes in the bottom for drainage. Mark one container A; this is the control group. Plant the seeds in container A at the depth and distance apart recommended on the seed packet.

Mark the other containers B, C and D. These are the experimental groups. Assign a different number of seeds to plant in each container, such as 10 in container B, 20 in container C, 30 in container D, etc.

Place the pots together in lots of natural light. They should have the same growing conditions so the results of plant growth can be directly compared with the number of seeds planted. Use a measuring cup to water the containers with the same amount of water at the same time. Measure the plant height weekly or bi-weekly, and record it on a chart.

What’s Happening?

Most living things need food, water, shelter and space to survive in their habitat. Competition for survival occurs at all times as organisms seek out the resources they need. Any plant that can get more water, nutrients and sunlight than its neighbors will grow and reproduce more successfully.