HEIRLOOM. This leafy green relishes hot weather, so plant in spring for a nutritious summer harvest. Soak seeds 24 hours before planting. Harvest the young plant tips for best flavor and cook like spinach or swiss chard. Resistant to many garden pests that plague more common plant families. These frost intolerant plants are not true spinach, but they will satisfy a mid-summer craving for nutrient dense greens when it's too hot for most other plants.