MORRIS – The Northern Lights series of hardy azaleas are now flowering at the West Central Research and Outreach Center Horticulture Display Garden. This series of azaleas are sufficiently hardy for USDA Plant Hardiness Zone 4. Azaleas, best known for their showy, colorful fragrant flowers, can be grown in many Minnesota landscapes. Azaleas require an acid soil for best growth. If your soil is not acidic, the addition of acid peat, sulfur, or ferrous sulfate can lower the soil pH.