How to Grow Petunia Seeds

Increase petunia yields by sowing many petunia seeds.

Petunia plants are grown as annual plants in nontropical regions. These easy-to-grow flowers come in a variety of forms, colors and growing habits with a long blooming period from spring to early fall. Although petunia flowers are readily available at nurseries and garden centers as transplants, you can greatly increase your petunia flower production by sowing petunia seeds. One challenge that presents itself with sowing petunia seeds is their tiny size. With the proper supplies and simple seed-sowing knowledge, any gardener can start petunia plants indoors by sowing seeds early.

Things You'll Need

• Peat pellets
• Seed-starting tray
• Small bowl
• White paper plate
• Toothpick
• Spray bottle
• Grow lights
• Good-quality potting soil
• Peat pots
• Drainage tray
• Liquid fertilizer

Instructions

1. Refer to the germinating time indicated on the package of the petunia seeds to know exactly when to begin sowing indoors.

2. Place dry peat pellets into a seed-starting tray. Pour the recommended amount of water into the seed-starting tray to moisten and plump the peat pellets.

3. Fill a small bowl with water. Pour the petunia seeds onto a white paper plate. Dip the tip-end of a toothpick into the bowl of water. Use the moistened toothpick tip to pick up one petunia seed. Place one petunia seed in the center of one plump peat pellet. Repeat this process for the remaining peat pellets.

4. Pour water into a plastic spray bottle. Use your fingers to press the petunia seeds gently into the peat pellet soil, and use the spray bottle to mist the tops. Do not cover the seeds with soil.

5. Cover the seed-starting tray with the included plastic dome. Set the seed-starting tray in an area receiving indirect bright light. Keep the peat pellets moist with the spray bottle as they begin to germinate in about 10 days.

6. Remove the clear plastic cover when the petunia seedlings emerge from the tops of the peat pellets. Set the tray under grow lights, keeping a 4- to 6-inch space between the bottom of the grow lights and the top of the petunia seedlings.

7. Set the grow light timer to stay on for 12 to 16 hours per day. As the petunia seedlings grow, adjust the grow lights to maintain the 4- to 6-inch space.

8. Fill peat pots with good-quality potting soil and place them onto a drainage tray. Transplant the petunia seedlings into the peat pots when they grow three leaves. Mix liquid fertilizer and water together according to the fertilizer instructions, and water the transplanted petunia plants until water begins to flow out the bottom into the drainage tray.

9. Keep the peat pots under grow lights until one week before the last predicted frost date. Continue to water regularly, whenever the peat pots begin to dry.

10. Take the peat pots outdoors in a sunny location one week before the last frost date. Keep the peat pots outdoors during the day, bringing them back indoors at night to harden them off to outside conditions.

11. Plant the petunia plants outdoors in well-draining soil located in a sunny area, spaced 12 inches apart. You can plant the peat pots directly into the soil. The roots will grow through the peat material.

References

• Iowa State University Extension: Selecting and Planting Petunias
• Mother Goose: How to Plant Tiny Seeds