Botanical name: Allium sppCommon names: Allium, ornamental onionUSDA zones: 3 to 9, depending on speciesWater requirement: Regular water while bloomingLight requirement: Full sunMature size: Varies by speciesTolerances/environmental benefits: Drought tolerant, deer and pest resistantEvery spring and summer, orbed clusters of white, pink, purple, red, yellow and even blue flowers appear on the tops allium's tall, leafless stems, making the garden a living party. Floral lollipops poke their heads above surrounding foliage and give a friendly garden welcome. I feel like these flowers would be smiling if they could.With more than 500 species to choose from, it can be hard to pin down which allium is right for you. For now, here are three popular and highly rated allium species.