How to Grow Petunia

Start Petunia seeds indoors 10 weeks before your last frost date, then transplant outdoors 2 weeks after the last frost. Use the search on this page to find exact dates for your ZIP code or city.

Petunia typically matures in about 75 days from planting. Exact timing varies by variety, soil conditions, and local climate.

Petunia should be started indoors 10 weeks before the last frost date. This gives seedlings time to establish before being transplanted outside after frost danger has passed.

Petunia requires full sun (6-8 hours) to thrive.

Space Petunia plants 12 inches apart to allow adequate airflow and root development.

Petunia has moderate (1 inch/week) water needs. Consistent moisture is important especially during germination and early growth.

Yes — seed saving difficulty for Petunia is rated moderate. Allow seed pods to form after flowers fade. Harvest when the small pod turns tan and begins to split. Collect tiny seeds in a bowl when pod splits, dry 1 week before storing.

Properly dried and stored Petunia seeds remain viable for up to 3 years. Store in a cool, dark, dry location in an airtight container with a silica gel packet for best results.

Many commonly sold Petunia varieties are F1 hybrids, meaning seeds saved from them will not grow true to the parent plant. For reliable seed saving, look specifically for open-pollinated or heirloom varieties.