We strongly recommend direct-sowing your Collinsia heterophylla on finely-raked, medium-to-rich moist soil, but if you do start them indoors, be sure to use biodegradable peat pots or—our favorite—Cowpots—when growing Chinese houses from seed. That way, you can set out your seedlings with minimal disturbance to their fragile roots.
Seed Treatment: None required.
When to Plant Outdoors: Direct sow in late fall or early spring.
When to Plant Indoors: Start your seeds in a sunny window or under a fluorescent plant light 6 to 8 weeks before your last spring frost.
Seed Depth:Collinsia heterophylla seeds should be surface-sown. If they're covered by more than 1/8" soil, they're unlikely to germinate.
Seed Spacing: 12" to 18".
Days to Germination: 10 to 30 days.
Transplanting Tips: Transplant young Chinese houses when they're about six inches tall. Harden them off for about a week before planting them in their intended spot.