Keep in mind when planting that Ellenbank Jewel is thought of as hardy, so Ellenbank Jewel will tend to go dormant or grow slowly over the winter months.
By our calculations, you should look at sowing Ellenbank Jewel about 49 days before your last frost date.
Ensure that temperatures are mild and all chance of frost has passed before planting out, as Ellenbank Jewel is a hardy plant.