Troubleshooting

Root rot is caused by overwatering. Healthy roots are white and firm. Rotted roots are brown, mushy, and smell bad.

Rosemary dies from overwatering, poor drainage, or cold. It's a Mediterranean herb that wants dry, sandy soil.

Seed starting mix is sterile and light for germination. Potting soil has nutrients for established plants.

Total germination failure isn't the end. Diagnose the cause, fix it, and replant.

The paper towel test tells you in 7 days whether old seeds will germinate. 10 seeds, 1 damp paper towel, 1 ziplock bag.

Seedling yellow leaves come from 4 causes: overwatering, not enough light, nutrient deficiency, or cold stress.

Seedlings fall over for 5 reasons: damping off, leggy growth, root damage, transplant shock, or physical damage.

Purple seedling leaves usually mean cold stress or phosphorus deficiency.

White spots on seedlings are usually powdery mildew, sunscald, or water spots.

Seedlings stop growing for 6 reasons. Run through these checks in order to find the cause.

Below 50°F, most seeds go dormant. Between 50-65°F, germination slows to 2-3x normal time.

If your seeds haven't sprouted after 10 days, it's almost always one of 7 causes. This decision tree identifies which one in under 2 minutes.

Above 85°F, some seeds go dormant or die. Lettuce and spinach are most sensitive. Shade the soil and water more often.

Soil dries too fast from 5 causes: small pots, hot weather, peat-based mix, dry air, or root-bound plants.

Bad soil smell means anaerobic bacteria — from overwatering, poor drainage, or decomposing organic matter.