This article was last updated by on

How Long Do Red Onions Take To Grow? [Planting Guide]

Want Red Onions for your curry but isn’t readily available in stores? How about growing it, as Red Onions do not take long to grow and attain harvestable size!

Generally, after planting, Red Onion takes around 100-120 days to reach maturity. But as a biennial crop, it takes two years to complete the lifecycle from seeds to flowering.

There are several ways to grow Red Onion in your home, each slightly different in its time of maturity. So, follow along to learn more about Red Onions.

Red Onion Growing Stages 

Before the onions are harvested, they go through several growth stages. And each stage has its culinary use. 

The red bulb makes the core base of different regional curries, while the green leaves, popularly known as “scallions,” adds freshness to our dish. 

Moreover, knowing the growth stages helps you with the chores of the plant, like the right time to plant, fertilizer application, and harvest.

Four different stage of onion.
The seedling stage is missing when growing onions from bulbs.
  • Germination: Onion seeds begin to sprout and send out roots.
  • Vegetative growth: Then the seedling produces 8-10 leaves and grows in height until it reaches maturity.
  • Bulb initiation & growth: Once the plant has grown to a certain size, it forms a bulb at its base. Under proper conditions, the onion bulb grows larger and fills out. The outer layer will also begin to dry and turn brown.
  • Maturation: Finally, the onion plant stops producing leaves, and the existing leaves turn yellow and dry out, indicating the onions are ready for harvest. At this point, the bulb is fully mature. 

How Long Do Red Onions Take To Grow?

The purplish-red skinned onion belongs to the genus Allium and has pungent linear leaves.

Generally, you can grow Red Onion by starting the seed or via bulb/sets.

Regardless of the method, Red Onion takes around four months (100-120 days) to reach harvestable maturity. But, as a biennial, it takes two years to complete the lifecycle, i.e., seed to the dormant bulb in the first year and flowering in the following spring.

Interestingly, they make a good companion with marigolds, raspberries, and lettuce for their easy care and growth pattern.  

Onion from Seeds

Growing onion from seeds is one of the most economical ways to get red bulbs. Also, these onions are better in terms of their quality.

However, you’ll have to wait 90-120 days before the onions are ready to harvest, which involves several time-consuming steps.

Basically, you’ll have to start the seeds 8-10 weeks prior to the last frost date in your area for better establishment of the roots.

Then, as the seedlings are 4-6 inches tall and have developed several sets of leaves, transplant them outdoors in a sunny location. 

Further, apply a balanced fertilizer every three to four weeks during the growing season and ensure consistent moisture until the bulbs are ready to be harvested.

Onion from Bulbs or Sets

Unlike the seed method, growing onions from bulbs or sets takes less time as the bulb doesn’t go through the germination stage. 

Firstly, choose a developed onion bulb, 3/4 inch in diameter and no larger, as larger ones tend to speed quicker.

Once you plant the bulb in well-draining soil at a distance of 6-10 inches apart in the early spring, you can harvest the bulb within three to four weeks.

Further, cut down on watering once the leaves start turning yellow. Or else you’ll end up rotting the bulb.


From Editorial Team

Provide proper care!

Keeping the soil moist for onions is essential, but they aren’t great at taking up water.

So, ensure you water only when the top layer of the soil is dry, and maintain enough distance between the plants for ample growing space. 

Also, choose a variety of onion that suits your local weather conditions.