Assessing Acorn Viability
Not all acorns will be healthy. Some may not be completely formed or may have insect damage. Visually inspect the acorns for holes. Pinholes may indicate insect activity inside. These acorns may still grow, but may not be as healthy or have as much stored energy to help them sprout. Squeeze the acorns to make sure they are solid and shake them to ensure they don’t rattle. Squishy and rattling acorns may be dissected to explore what is wrong with them.
Acorn “Sink & Float”:
The acorn “sink & float” test can be an easy way to sort a large quantity of acorns quickly. Be cautious about using this test prior to storage as it may stimulate early germination and increase mold problems. Hand sorting is preferred for acorns that will be stored in the refrigerator for several months.
Place acorns in a large container and cover them with water. Immediately remove any acorns that float. Save the “floater” acorns for further investigation.
Allow the seeds to soak for at least 12 hours. Remove seeds that have floated to the top of the container.
Drain off the water and plant the “sinker” acorns in containers or directly outdoors.
Using the “floater” acorns, ask students to propose hypotheses about what may have caused these seeds to float. Allow students to dissect the seeds to investigate their contents. Ask them to record their observations about the squishy, rattling and “floater” acorns in their journals.