Collinsia is a wonderfully easy annual to grow from seed. Like Alyssum and a handful of others, it's pretty much a matter of simply placing the seeds where the flowers are to grow and add some water. The only challenge with Collinsia seeds is that the plants tend to fade in very hot summer weather.
Season & Zone
Exposure: Full sun to partial shade
Direct sow in early spring when the soil is cool and when a light frost is still possible. Sow at three week intervals for a longer continuous bloom time.
Sow seeds 5mm (1/4”) deep. The optimal soil temperature for germination is 18-21°C (65-70°F). Seeds should germinate in 14 to 21 days.
Space plants 15-30cm (6-12") apart in full sun in mild areas, or in partial shade where summers are hot. Collinsia prefers rich, moist, well drained soil with a pH range of 5.0-8.0. The plants may self-sow. Deadhead often to extend the bloom time.