Once those hair-like green sprouts emerge, they will be fragile. During this month, the seedlings are focusing all their energy on developing their first "true leaves" (the leaves that look like the adult plant, distinct from the initial seed leaves).
not cover with soil. Keep at 70–80°F. Seedling Stage 2–3 weeks First "true leaves" appear. Move to cooler temps (65°F) and provide 12–16 hours of light. Vegetative Growth 4–6 weeks Rapid leaf and stem development; plant begins to look "bushy". Hardening Off 7–10 days Move plants outdoors gradually to acclimate to wind and UV rays. Flowering 12–14 weeks First blooms typically appear ~80–100 days after sowing. Recommended Planting Schedule Because petunias grow slowly and are highly sensitive to frost, they should be started indoors early. www.gardenia.net +1 10 sites When to Start Petunia Seeds Indoors — 5 Simple Steps Feb 21, 2026 — how long does it take to grow petunias from seeds
Growing petunias from seed generally takes from the time you sow them indoors to when they are ready to bloom in your garden. Because they grow slowly at first, you should typically start them indoors about 8 to 10 weeks before the last expected frost in your area. General Growth Timeline Once those hair-like green sprouts emerge, they will
With a 10 to 12-week timeline in mind, a sunny window (or grow lights), and a little pinch here and there to encourage branching, you’ll be rewarded with a garden full of color that is truly home-grown. Happy planting Keep at 70–80°F