Keep in mind when planting that Liberty Bronze is thought of as very hardy, so this plant will tend to survive through freezing conditions. Ideally plant in loamy soil and try to keep the ph of your soil between the range of 6.0 and 7.0 as Liberty Bronze likes to be in weakly acidic soil to neutral soil.
By our calculations, you should look at sowing Liberty Bronze about 56 days before your last frost date.
Ensure that temperatures are mild and all chance of frost has passed before planting out, as Liberty Bronze is a very hardy plant.