Onions are versatile and delicious vegetables that can be grown in various climates. Let’s dive into your questions:

1. Growing Zones for Onions in the US:
   • Onions are categorized into different varieties based on their day-length requirements:
     • Short-day onions: These varieties need 10-12 hours of daylight to form bulbs. They are ideal for USDA zones 7 to 9.
     • Intermediate-day onions: These start forming bulbs at 12 to 14 hours of sunlight daily. They are suitable for zones 5 and 6 and can grow well in milder climates but don’t produce as well in the southernmost US states.
     • Day-neutral onions: These tend to be very sweet, mature in 110 days, and will grow in any hardiness zone but typically do their best in zones 5 and 6. Varieties include Candy Onion, Super Star, Red Candy Apple, and Monastrell.
     • Zone 4b is a region with a unique climate that presents challenges for onion growers. To cultivate onions successfully in this zone, plant them about 2-4 weeks before the last expected frost date, which is approximately April 28th.
2. Growing Onions Indoors:
   • If you’re short on outdoor space, you can grow onions indoors! Here’s how:
     • Choose a deep container:Select a container that is at least 6 inches (15 cm) deep. The width can vary based on available space and how many onions you’d like to grow.
     • Use simple potting mix soil: Onions are hardy and don’t need complex or expensive soil. Leave about 1 inch (2.5 cm) of space between the soil and the container’s top.
     • Save an onion bulb: Use the part of the onion where the roots grow (usually cut off during cooking). Plant it about 2 inches (5.1 cm) deep in the soil.
     • Provide sunlight: Place your potted onion where it can get 6-7 hours of sunlight per day. If natural sunlight is insufficient, supplement with an artificial light source like a fluorescent or incandescent light or a dedicated grow lamp.
     • Remember, onions are cut-and-come-again vegetables, so you’ll have a continuous supply if you follow these steps.

Happy growing!

Check out the USDA Plant Hardiness Zone Map here. Or, for a quick glance at your general plant hardiness zone, use our map.