Container Plant Information: Onion

How To Grow

1. Container Selection: Choose a deep container with a minimum depth of 10-12 inches. Onions require space for bulb development, so a width of at least 12 inches is also recommended. Ensure the container has drainage holes to prevent waterlogging.
2. Soil: Fill the container with well-draining potting mix or a loamy soil amended with organic matter. Onions prefer slightly acidic soil with a pH level between 6.0 and 7.0.
3. Variety Selection: Select onion varieties suited for container growing, such as ‘Evergreen Bunching,’ ‘Red Baron,’ or ‘White Lisbon.’
4. Location: Place the container in a location with full sun. Onions require at least 6-8 hours of sunlight daily for optimal growth.
5. Planting: Onions can be grown from seeds, sets, or transplants. If starting from seeds, sow them directly into the container, following the spacing recommendations on the seed packet. If using sets or transplants, plant them about 1 inch deep and 2-3 inches apart.
6. Watering: Keep the soil consistently moist but not waterlogged. Onions require regular watering, especially during dry spells, to promote bulb development. Avoid overwatering, as it can lead to rotting.
7. Fertilizing: Onions are light feeders and do not require heavy fertilization. However, you can apply a balanced liquid fertilizer or compost tea every 3-4 weeks to promote healthy growth.
8. Mulching: Apply a layer of organic mulch around the base of the onion plants to help retain moisture, regulate soil temperature, and suppress weeds.
9. Pest Control: Monitor the onion plants for pests such as onion thrips, onion maggots, and aphids. Use organic pest control methods such as row covers or insecticidal soap to manage infestations.
10. Harvesting: Harvest onions when the tops begin to yellow and fall over. This usually occurs 90-120 days after planting. Gently lift the onions from the soil, taking care not to damage the bulbs. Cure the onions by drying them in a well-ventilated area for 2-3 weeks before storing.

Check out our detailed guide to grow onion in a container.