Try to plant in a location that enjoys full sun and remember to water moderately. Keep in mind when planting that Astra Double Blue is thought of as very hardy, so this plant will tend to survive through freezing conditions. Ensure your soil has a ph of between 6.1 and 7.8 as Astra Double Blue is a weakly acidic soil - weakly alkaline soil loving plant.
Growing Astra Double Blue from seed
By our calculations, you should look at sowing Astra Double Blue about 49 days before your last frost date.
Transplanting Astra Double Blue
Ensure that temperatures are mild and all chance of frost has passed before planting out, as Astra Double Blue is a very hardy plant.