Onion Planting Tips


Onions are native to Southwest Asia but now cultivated all around the world. A member of the Allium family, Onions are an easy crop to grow in the home garden.

If you planted onions and they did not perform well first make sure you planted the right variety for your region. Onions are phototrophic - meaning a specific amount of daylight is necessary for onions to from bulbs. There are three varieties of onions: Long day, short day and day neutral.

  • Plant in fertile, well drained soil

  • Plant where they will receive full sun

  • Onions are phototrophic meaning they need a specific amount of daylight for the onion to form bulbs.

Companion- Chamomile and summer savory improve their flavor. Also beets, Brassicas, carrots, dill, kohlrabi, leeks, lettuce, strawberries and tomatoes are good companions.

Avoid- Peas

Types- There are three varieties of onions: Long day, short day and day neutral.

Long Day

  • 14 to 15 hours of daylight to bulb

  • Prefer colder temperatures zones 1- 6

  • Plant in winter to early spring

Short Day

  • 10 hours of daylight to bulb

  • Preferred variety for the south

  • Need milder winter temperatures zones 7-12

  • Plant in fall

  • Harvest in spring

Day Neutral

  • Form bulbs regardless of photoperiod

  • Prefer warmer temperatures ideal for zones 5-6

  • In south plant in fall harvest in spring

  • Plant in winter

  • Harvest in spring

Planting and Harvesting- Plant onions in fertile, well-drained soil.  Remove all rocks and large sticks from the planting site. Work/till the ground to a depth of 8”-10”.  Place in a bed that receives full sunlight.

Onions can be grown from seed with some proper care and are the most cost-effective.  Plant seeds ¼” deep. Place every 1 inch. Thin plants to one every 2 or 3 “ after plants have reached 6” tall. Most people prefer to use transplants. Bury the roots ¾” deep in the soil.  Do not plant deeper than 1”.

A balanced, organic fertilizer is all onions need.  After planting, apply ½ cup per every 10’ row every 2- 3 weeks. Or before planting mix in 2.5 lbs of balanced organic fertilizer for every 100 square foot of garden space.  Stop fertilizing when bulbs begin to form.

The ability to harvest onions at various stages is the reason onions are a staple in my garden.  You can plant two or three times the desired amount and continually harvest them at different stages. Harvest green onions when they are around the size of a number 2 pencil.  

To form bulbs, allow the plants to grow large.  Whenever the main stem begins to lean over and touch the ground, the onions are ready to harvest.  Remove them from the garden and allow them to dry in the sun for a day or two before removing the main stem from the bulb.   

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