For optimal germination rates, initiate seed propagation indoors under controlled conditions—unless the species exhibits a high sensitivity to root disturbance. This approach allows precise regulation of temperature, humidity, and light, improving germination consistency and seedling viability. Do not skip any recommended seed treatments, as they are essential for uniform and successful germination.
Buddleja davidii seeds require light to germinate.
Seed Treatment (Before Planting)
Step 1: Surface-sow seeds on moist seed-starting mix. Do not cover.
Step 2: Cold stratify by placing the sown tray in the refrigerator for 28–42 days (4–6 weeks). Keep moist but not soggy.
Check regularly: If seedlings sprout in the fridge, remove them gently and plant immediately.
When to Sow Indoors
Start indoors 8–10 weeks (56–70 days) before your last expected frost date.
When to Sow Outdoors
Sow outdoors in late fall in a cold frame or prepared seed bed. Seeds will naturally stratify over winter and germinate in spring.
Optimum Germination Temperature: 18–22°C (64–72°F)
Germination Time: 30–45 days after stratification
Light Requirements for Germination
Requires light to germinate. Do not cover seeds.
Use grow lights to maintain 12–16 hours of light per day.
Humidity
Use a humidity dome or clear cover to maintain consistent moisture during germination. Open the dome briefly once per day to allow fresh air in and reduce mold risk. Remove the dome entirely once seedlings emerge.
How to Sow Indoors
- Fill shallow seed trays or small pots with fine, moist seed-starting mix.
- Gently press seeds onto the surface—do not bury.
- Mist lightly and cover with a humidity dome.
- Provide warmth, light, and air circulation.
Post-Germination Care
- Remove dome once seedlings appear.
- Grow under strong light or full-spectrum grow lights.
- Transplant to individual pots when they have at least 2 sets of true leaves.
- Harden off seedlings before planting outdoors.
Final Spacing & Growth Info
- Plant outdoors after frost, spacing 90–120 cm (36–48 inches) apart.
- Fast-growing deciduous shrub.
- Mature height: 1.5–3 m (5–10 ft)
- Attracts butterflies and pollinators. Drought-tolerant once established.
- Prune back in early spring to encourage vigorous growth and blooming.