Effect of Soil pH on Radish Germination

Radish seeds (30 per condition) Potting soil White vinegar (to lower pH) Baking soda solution (to raise pH) pH test strips 5 seed trays Watering can Grow light

1. Prepare 5 soil conditions: pH 4, pH 5, pH 6, pH 7 (control), pH 8. 2. Adjust pH using diluted vinegar (acidic) or baking soda solution (alkaline). 3. Verify pH with test strips before planting. 4. Plant 30 radish seeds per tray, 1cm deep, evenly spaced. 5. Water equally (50ml daily) and maintain under grow light (16h on / 8h off). 6. Record germination count daily for 10 days. 7. Measure seedling height at day 10.

pH 4: 8/30 germinated, avg height 1.2cm, yellowed leaves. pH 5: 22/30 germinated, avg height 2.8cm. pH 6: 28/30 germinated, avg height 4.1cm, healthiest appearance. pH 7: 26/30 germinated, avg height 3.6cm. pH 8: 18/30 germinated, avg height 2.1cm, some brown leaf tips. Germination timing: pH 6 seeds sprouted fastest (day 2-3), pH 4 slowest (day 5-7).

Radishes prefer slightly acidic soil (pH 6.0-7.0), which matches our results. The dramatic failure at pH 4 shows how extreme acidity inhibits germination. Good for teaching about soil science and agricultural chemistry. Could extend with different plant species to compare pH preferences.