Plants are patient, honest experimental subjects: give two groups different light, water or soil and they will show you the answer — as long as you wait long enough and measure carefully. These projects run from one-week seed germination tests to multi-week growth comparisons.
36 published projects in this collection
Plan backwards from your deadline: germination experiments need about a week, growth comparisons three or more. Use several identical pots per condition — one plant can die for reasons that have nothing to do with your variable — and measure height or leaf count on a fixed schedule.
Photograph your setup on day one and every measurement day. A simple photo log plus a dated data table is the difference between 'my plants grew' and evidence a judge can trust.
A materials list with costs, numbered steps, safety guidance, the variables to change and control, and a data table you can fill in — plus community results from other builders once people start sharing theirs.
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By school level
By difficulty
Preparing for a fair? Read the science fair guide or record your data in the lab.