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Onions Growing Stages: How Do Onions Grow

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

Onions are very much seen in vegetable gardening. Understanding the growing stages can help boost your knowledge and make you a better gardener.


Compared to many other garden vegetables, onions have a much longer growing season requirement. This longer season is a result of the time needed for the plants to form bulbs. For it to germinate from seed to a mature, dry bulb, it takes between 100 to 175 days. However, the variety and local growing conditions also depend.

Tip: learn more about how long onions take to grow


Onion is typically grown as annual crops, harvesting the onion plants when the bulb is mature, with the vegetative tops beginning to die. In reality, onions are biennial plants I.e two growing seasons are required for its germination from sees to plant which produces its own seeds.


I) Planting: Onions can be planted at two different times of the year, your growing zone being a factor to be considered. When planting in spring, endeavor to get transplants or plant onion sets in your garden beds when you are having a temperature that is consistently above 28°F.

This should be in late March or early April. If planting from seed, plant the seeds 8 to 10 weeks beforehand. For fall, work towards planting your sets in August or September. Thus, giving them 6 – 8 weeks to grow before falling temperatures. Once your seeds are planted, ensure to keep the soil moist at all times.

II) Germination: Here, the first step is the emergence of the radicle through the seed coat. Once it emerges, it absorbs moisture as well as nutrients from the soil and this is used to drive the plant’s growth.

III) Sprouting: Here, the first shoot develops and emerges through the softened seed coat. The shoot is directed to grow upward through the soil by gravitational forces so as to reach for the sun. Once the shoot emerges through the soil surface, the focus of the seedlings is changed and there is a direction of the plant’s energy to developing leaves.

Other stages which occur in the first year include the formation of the first true leaf, the “Leek” stage, the bulb initiation stage, the bulb development stage, maturation, and vegetative senescence.

Read also: 7 Onion Growing Tips For Maximum Harvest


I) Vegetative Growth: Onions begin another active growth when springtime temperatures begin to climb. There is a triggering of the cells to start developing and elongating by the hormones within the bulb.

II) Flowering Stalk Emerges: Here, vegetative growth stops, and the plant shoots up a flowering stem in preparation for the end of its life cycle. Upon the full formation of the stalk, buds grow, followed by a bloom of a white or purple flower at the top.

III) Formation of seeds: Pollination by butterflies, birds, bees causes the formation of seeds. There is a translocation of nutrient reserves from the onion bulbs to the seeds to be used in germination.

IV) Senescence: Upon the formation of the seeds, the onion’s life cycle is complete. Due to the direction of a lot of the onion’s resources towards developing seeds, little is left for further plant growth. As a result of this, plant growth hormones induce the genes for senescence, and the plant perishes.

Read also: Can You Compost Onions? The Detailed Guide To Onions Composting


I hope you find this article helpful. I would like to hear from you. So, let me know if you have any questions about the growing stages of onions. Also, learn how to plant onions here.

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