Large purple alliums
image by AnnaKika: flickr.com
For a newcomer to the world of ornamental onions, the showstopping power of alliums is astonishing. Alliums can grow up to 3 feet tall and have bursts of flowers which look like living fireworks. Some of these bulbs are as large as a child's head. The blooms come in colors from deep fuchsia to true blue. They are also favorites of hummingbirds. Ornamental onions also make good cut flowers and dried flowers.
Select a full-sun location with well-draining soil. You can increase drainage in clay soils by amending the existing soil up to 50 percent with an even blend of compost and peat moss.
Plant alliums during September or October, approximately 6-8 inches apart and 3 inches deep with the pointy end up.
Add bulb fertilizer to the bed. Alliums have fewer pest problems than other bulbs, but you can add some blood meal to the planting bed to discourage rodents.
Water the soil well until the area is thoroughly soaked in order to help roots develop. Water regularly during the season, but make sure that there is no standing water.
Cut flowers once they have started blooming if you would like to enjoy them indoors or dry for arrangements. However, this is up to you, as it will not produce more blooms.
Leave foliage after blooming has finished in order to allow the bulbs to gather energy for the next blooming season.
Cut foliage after the leaves begin to yellow. This should be in midsummer when the allium begins to go into dormancy.