Hard frost turns the starches to sugar, improving flavor.
Keep in mind when planting that Joan is thought of as hardy, so this plant will survive close to or on freezing temperatures. Joan requires a loamy and clay soil with a ph of 6.5 - 7.2 - it grows best in weakly acidic soil to weakly alkaline soil.Try to direct seed. Root vegetables don’t like to be disturbed by transplanting.
Ensure that temperatures are mild and all chance of frost has passed before planting out, as Joan is a hardy plant.