Petunias can be propagated from cuttings or seeds.
From cuttings
- Take cuttings: In the summer, cut 10 cm long shoots from a petunia plant, preferably ones without flowers.
- Prepare the cuttings: Remove all leaves except the top two pairs, and dip the end of the stem in rooting hormone powder.
- Root the cuttings: Place the cuttings in a glass of lime-free water, or in a moist medium like sphagnum moss or coconut coir. You can also wrap the base of the cutting in plastic to create a mini greenhouse.
- Place in a cool, dark place: Keep the cuttings in a cool, dark place for about three weeks.
- Check for roots: Gently pull on a leaf to see if roots have formed.
- Plant in pots: Once roots have formed, transplant the cuttings into small pots with moist growing soil.
- Acclimate: Gradually move the potted cuttings outside to full sun.
From seeds
- Prepare the soil: Fill a seed tray or small pots with seed-starting mix.
- Sow the seeds: Sow the seeds indoors 10-12 weeks before the last frost date in your area.
- Water: Keep the soil moist but not soggy.
- Watch for germination: The seeds should germinate on their own.