This is from the range of Xiphium Irises (Spanish Iris) created in the Netherlands in 1891. They are popular with florists, but equally good in the garden. I. Professor Blaaw is the deepest of blues with its fall marked with yellow. You should normally see two buds swelling the stem before flowering - much more engaging than simply collecting them from a shop. May / June 18-24” (45-60cm)
Planting instructions
Plant the bulbs 4" (10cm) deep 4-6" (10-15cm) apart, in a well draining position in full sun, watering them in well. Thereafter, water moderately.