Large flowering allium, such as Gladiator are best planted in groups of 3 or 5, you can plant 3 bulbs per square foot for the best affect. The flowers are large round and purple, growing 6-8" in diameter, in late Spring to Early Summer. Gladiator is a hybrid variety from a cross between Allium aflatunense and Allium macleanii, it is similar to Allium giganteum, however the flowers typically are slightly larger on the Gladiator.