Look to ensure a distance
11.7 inches (30.0 cm) between Martina Verhaert seeds when sowing to make sure your seedlings have enough space.
By our calculations, you should look at sowing Martina Verhaert about 42 days before your last frost date.
Martina Verhaert is hardy, so ensure you wait until all danger of frost has passed in your area before considering planting outside.