Answer: These seeds (Verbena bonariensis) should germinate within two weeks at a soil temperature of about 68 degrees. Since the soil temperature is usually a bit below room temperature, you might use some gentle bottom heat to maintain that extra warmth. This plant will self seed in the garden if the seeds fall on old decomposed mulch or a similar seedbed, so you could certainly try direct seeding. However, the plants grow best in warm weather and need to reach a certain maturity before they begin blooming, so starting them indoors will give them a head start. In milder winter areas such as zone 7 and warmer, this plant is a perennial. In a cooler area they may not begin to bloom until late summer.
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