How to Grow Walla Walla Onions in Containers

Onions grow in a wide range of shapes, sizes and flavors, but always develop underground as root crops. Any container for onion growing must take this into account and have adequate depth and width. Walla Walla onions grow to 4 inches in diameter and so need very large pots. Give the onions lose, rich soil for quick and easy growth, and keep them warm and moist for best harvest.

Pots/containers
Potting soil
Organic compost
Fertilizer

Instructions

- 1
  Use deep, large 5-gallon containers with drainage holes for these bulb onions. Pots and containers should measure at least 6 inches deep and wide for single plantings, and larger for multiple plantings. The Ohio State University Extension recommends 10 inch pots for onion crops.
- 2
  Fill the pots three-quarters full with a mixture of half potting soil to half organic compost. This foundation provides moisture and nutrition for Walla Walla onions, with a loose, crumbly consistency for bulb formation. Turn 8-16-16 or 5-10-10 fertilizer into the soil for long-lasting nutrition.
- 3
  Plant Walla Walla onion seeds 1/2 inch deep and 4 to 6 inches apart. Give each onion plant adequate space to avoid retarded bulb growth.
- 4
  Put the pots in sites with full sunshine or artificial light and temperatures of 55 to 75 degrees F. Water the onions with 2 inches of water every week and expect sprouting in eight to 10 days.
- 5
  Give the onions water-soluble 15-30-15 or 20-20-20 fertilizer at midseason to encourage bulb growth. Use the feeding as one of your weekly waterings.

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