Germinating Sycamore Seeds: Cold Stratification in Oklahoma

A reader in northern Oklahoma asks if sycamore seeds need 90 days below 40°F, given their climate doesn’t consistently stay that cold.

Natural vs. Artificial Stratification

Planting sycamore seeds outdoors in Oklahoma (Zone 6/7) provides sufficient chilling. Alternatively, stratify artificially:

1. Sow seeds in moist potting soil in a pot.
2. Seal in a plastic bag; refrigerate 90 days.
3. After chilling, move to warmth; germination follows.

Why Seedlings Don’t Appear Naturally

Lack of seedlings is usually due to mowing, landscaping, and animal predation—not failed chilling. Seeds germinate but don’t survive in maintained lawns.