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How Long Does Onion Take To Grow – Now Answered

by Idris Ya'u
This article was fact checked.
Helpful: 100%

There are varieties of onions and onions differ in shape, colour, size and flavour. Depending on the type of onion and whether your planting begins from seeds, transplants or sets, the time the onions mature varies as well. Taking these aspects into consideration before planting your onions will help you determine better when to expect the harvesting of your onion crop.


This takes the longest for onions to fully grow but when it comes to variety, onion seeds give the most choices. It can take up to five months before onions can be fully ready for harvest.

When starting your onion plants from seed, ensure the soil temperature is warm to nothing less than 50°F before sowing your seeds. In areas having mild winters, you can choose to plant varieties of short-day onions four weeks before the initial frost in fall.

Direct sowing in the garden may fail to give long-season onion varieties enough time to reach maturity, thus, starting from seeds work best for short-season varieties of onions and scallions. You can make use of pots, flats, or trays when sowing your seeds.

Related: Learn How To Grow Green Onions In Water At Home


You can decide to start the onion seeds indoors 8 – 12 weeks before the last frost date in relation to your area. This is applicable for a shorter period between planting and harvest.

Transplant seedlings outdoors when their growth has reached a quarter inch in diameter which should be about 2 – 4 weeks before the last frost date as regards your area.

In a gradual process, harden off onion seedlings before moving them outdoors. Ensure that the soil temperature is warm to nothing less than 40° and the air temperature is nothing less than 45 degrees.

For transplants to reach full maturity, it can take about two months. To get larger bulbs upon harvest, try to purchase transplants having larger bulbs.

Read Also: Learn how to grow onions at home without seeds.


For a quickest harvest, onion sets which are small, dormant plants can be planted. These onion sets are usually grown the previous year. In about two months, the onion sets will be fully mature and ready for harvest. These onion sets are less susceptible to diseases but growing them will limit your choice in onion varieties. Smaller sets are known to produce best so when selecting your sets, choose those that are no larger than half inch in diameter.


Green onions or scallions can be mature enough for harvesting after only 20 – 30 days. These onions are grown for their tender, green tops and harvested before the full formation of the bulbs.

Pearl onions which are also referred to as pickling onions, are harvested about 60 – 90 days after planting. As at this period, the bulbs are about 1 – 2 inches in diameter. Compared to larger onions which are pungent, this type of onions are sweet. They grow well in late winter to early spring in Mediterranean climates.

Read also: how To Grow Onions In A Plastic Bottle Step By Step


I hope you find this article helpful. I would like to hear from you. So, let me know if you have any questions about this topic. Also, if you want to know how to take good care of your garden, read our step by step guide on how to take care of a garden.

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