Planting petunia seeds is a rewarding process that can result in beautiful blooms. Here are detailed planting instructions for petunia seeds:

1. **Gather Supplies**:
- Petunia seeds
- Seed starting mix or potting soil
- Seedling trays or small pots
- Watering can
- Plastic wrap or a clear plastic dome
- Grow lights or a sunny windowsill
- Fertilizer (optional)

2. **Preparing the Soil**:
- Fill seedling trays or small pots with a moistened seed starting mix or potting soil. Make sure the soil is well-draining.

3. **Planting the Seeds**:
- Plant 2-3 petunia seeds per pot or cell in the tray. Press the seeds lightly into the soil, but do not bury them too deep.

4. **Moistening the Soil**:
- Water the soil gently after planting to ensure it is evenly moist. Avoid overwatering, as this can lead to seed rot.

5. **Covering the Seeds**:
- Cover the tray with plastic wrap or a clear plastic dome to create a mini greenhouse effect. This helps retain moisture and warmth, aiding germination.

6. **Providing Light and Warmth**:
- Place the tray in a warm location with indirect light or under grow lights. Petunia seeds require light to germinate, so do not cover them with soil.

7. **Maintaining Moisture**:
- Check the soil regularly and mist it lightly if it begins to dry out. Avoid letting the soil dry completely.

8. **Germination**:
- Petunia seeds typically germinate in 7-21 days. Once the seeds germinate, remove the plastic cover.

9. **Transplanting**:
- Once the seedlings have developed a couple of sets of true leaves, transplant them into individual pots to allow for proper growth.

10. **Growing Conditions**:
- Petunias thrive in full sun and well-draining soil. Water them regularly, but avoid overwatering to prevent root rot.

11. **Fertilizing**:
- You can fertilize the petunias with a balanced fertilizer once a month to promote healthy growth and blooming.

12. **Maintenance**:
- Pinch back the stems of the petunias to encourage bushier growth and deadhead spent blooms to promote continuous flowering.