How to Fertilize Giant Onions

Giant onions are one of the most impressive plants in the ornamental onion family. These flowers grow from bulbs and produce stalks up to 6 feet tall. Large orb-shaped clusters of purple or pink flowers develop at the top of each stalk during the spring and early summer months. Giant onions have similar requirements to other spring bulbs, including daffodils and tulips. They require suitable soil nutrition to replenish their bulbs each spring and summer, so they have the energy to produce new blooms the next year.

5-10-5 fertilizer
Bone meal
10-10-10 fertilizer

Instructions

- 1
  Spread 2 lb. bone meal over every 50 square feet of garden bed before planting the bulbs. Apply 1 lb. of a 5-10-5 blend fertilizer or a formulated bulb fertilizer on top the bone meal. Work both the bone meal and the fertilizer into the top 6 to 8 inches of the bed so the nutrients are incorporated into the root zone of the giant onions.
- 2
  Sprinkle 1/2 cup of 10-10-10 soluble fertilizer over every 50 square feet of the bed in spring, when the onions begin sending up their first shoots. Add 1 lb. of bone meal. Turn the fertilizers into the top inch of soil, then water thoroughly to help the fertilizers leach down to the root zone.
- 3
  Repeat the fertilizer application in fall about six weeks before the first expected frost. Use the same amount of fertilizer and bone meal for the fall application as you used in spring.

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Bulbs