Aconitum napellus Monkshood Description Tall stalks of pale blue-violet flowers in June and July. Grows best in moist soils. If you long for delphinium but don't have enough sun, aconitum makes a good substitute. Poisonous. Characteristics Hardiness Zone: 4-8 Light requirements: Part Sun Height: 36" Native: No Sizes & Prices Size: 2 Yr $13.98 Other Information All Monkshood Monkshood Aconitum napellus Zone: 4-8 Part Sun HT: 36" Monkshood Aconitum x cammarum 'Bicolor' Zone: 4-8 Sun/Part Sun HT: 3-4'