Sow this annual in cool soil as early as possible in the spring. Soak seeds for a few hours to soften seed coats to speed germination. Sow 2.5 cm deep and thin to 15 cm apart once true leaves appear. Pinch out growing tips to encourage branching and provide netting or poles for the vines to climb on. Sweet peas prefer rich soil and direct sun and flower best in cooler weather. Old Spice is a mix of the most heat tolerant heirloom sweet peas.