Keep in mind when planting that Erythrophylla Helix is thought of as tender, so it is really important to plant out well after your last frost date.
By our calculations, you should look at sowing Erythrophylla Helix about 91 days before your last frost date.
As Erythrophylla Helix is tender, ensure temperatures are mild enough to plant out - wait until after your last frost date to be on the safe side.