Keep in mind when planting that Rocket Yellow is thought of as very hardy, so this plant will survive though longer winters with little or no damage. Rocket Yellow requires a loamy soil with a ph of 6.0 - 7.0 - it grows best in weakly acidic soil to neutral soil.
By our calculations, you should look at sowing Rocket Yellow about 56 days before your last frost date.
Ensure that temperatures are mild and all chance of frost has passed before planting out, as Rocket Yellow is a very hardy plant.