Lupines are remarkably hardy (Z3-8), but in climates south of zone 6 the perennial hybrids work best used as annuals or biennials as they do not tolerate hot, humid summers well. Many gardeners choose to plant them like they would foxgloves – sowing them in flats in late spring, transplanting to pots in summer and setting out in fall for a spring bloom. In other climates, they are considered a shorter-lived perennial.
Seeds are protected by a very tough seed coat, which means that your results will improve if you first scarify with a file or sandpaper – or soak them for 24-48 hours. It’s an extra step for the gardener, but it’s a very clever way for nature to ensure that there are seeds in the soil for future seasons. Seeds must also make good soil/seed contact, so once they have been scattered and lightly covered with compost or soil (1/8”), it is important to tamp the soil down with a board or your feet. Seeds should germinate within 10 days.
Wherever they are sited, lupines require a sunny position and well-draining soil on the acid side if possible. They are calcifuge, which is a fancy way of saying they’re lime-haters, and will simply not tolerate alkaline soils or wet, boggy conditions. This is particularly true in the winter, when wet, cold conditions will rot the roots and kill the plant. If you have heavy clay soil, build it up with grit and sandy loam mixed with well shredded organic material, and then plant your lupines, taking care not to overwater.