Learning how to plant onions is one of the easiest gardening tasks you can do. Onions are easy to grow and the rewards are delicious. You can grow a good crop if you know when to plant, whether to use onion sets or seeds, and how to get the soil ready. When spring comes, little green sprouts appear. In just a few months, they turn into juicy, tasty bulbs.
One of my biggest passions in life has been gardening. I really worship there, and I really want to share what I’ve learned over the years with other people. This is exactly why I wrote my first book, The First Time Gardener: I want to help people who are just starting out.
You can learn a lot by doing things. In fact, I always say that failure can be our best teacher. But there are plenty of mistakes you can avoid by simply having a guide.
Onions are one of the most popular vegetables to grow in home gardens Their versatile flavor enhances so many dishes, and fresh homegrown onions simply cannot be beat! As an experienced gardener, the question I get asked most often is “How long does it take onions to mature and be ready to harvest?” The answer depends on whether you plant from seeds or sets
Onion Growth Stages
Before getting into timeframes, it helps to understand the growth cycle of onions. Onions form bulbs in response to day length, going through distinct growth phases:
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Germination: Onion seeds or sets sprout and seedlings emerge.
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Leaf Growth Foliage grows upward and roots establish,
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Bulbing: In response to day length, the onion begins forming a bulb.
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Bulb Maturation: The bulb swells with size and begins drying out as the greens die back.
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Curing: After harvest, the dried bulbs are cured for long term storage.
The time it takes onions to reach maturity depends on the variety and when bulb formation starts. Let’s look at timeframes starting from seeds versus sets
Onions from Seeds
When starting onions from seed, it typically takes around 4 months (90-100 days) for them to fully mature.
Here are the general timeframes for onions grown from seed:
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Germination: 10-15 days
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Leaf Growth: 4-6 weeks
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Bulb Formation: 2-3 months
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Maturation: 2-4 weeks after bulbing starts
Of course, the exact number of days depends on factors like onion variety, weather, and latitude. Short-day varieties mature faster than long-day. Cool temperatures slow growth while warm weather accelerates it.
In my USDA Zone 6 garden, I sow seeds indoors in February and transplant out in late March. With a short-day variety like ‘Candy’, my onions are ready to begin harvesting in July, about 4 months from seeding.
Starting onions early indoors gives them a head start on growth. Just make sure they are the right size before transplanting outside – pencil thickness is ideal.
Onions from Sets
Onion sets are miniature onion bulbs that let you skip the seedling stage. This speeds up the timeline by 4-6 weeks.
Here are the typical timeframes for onion sets:
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Leaf Growth: 2-4 weeks after planting
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Bulb Formation: 6-8 weeks after planting
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Maturation: 2-4 weeks after bulbing starts
So in total, you can expect onions grown from sets to be harvest-ready in 11-16 weeks, or around 80 days. I plant my sets in early spring and start harvesting bulbs in mid-summer, just under 3 months later.
With sets, there is no wait time for seeds to germinate and less leaf growth before bulbing starts. Be sure to pick the right variety of onion sets for your climate.
Tips for Faster Maturity
Here are a few tips that can help your onions reach maturity a little faster:
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Choose short-day or intermediate-day varieties if growing in northern zones
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Start seeds indoors up to 8 weeks before last frost
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Transplant seedlings early in the season while soil is cool
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Plant sets early in spring once soil can be worked
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Fertilize regularly with a balanced organic fertilizer
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Keep plants consistently watered, about 1 inch per week
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Control weeds to reduce competition for nutrients
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Use row covers or low tunnels to boost warmth in spring
Onions are such an easy and rewarding crop for home gardens. With proper timing and care, you can enjoy fresh onions in as little as 80 days from sets or 100 days from seed. Pay close attention to the maturation timeline for your variety and climate. Before you know it, you’ll be harvesting armloads of juicy, flavorful onions!
Is It Better to Grow Onions From Sets or Seed
Neither method is necessarily better. I think you should only start onions from seeds if you have a greenhouse and have experience gardening. Growing from seed takes more time and is more difficult, but it is less expensive.
I often grow my onions from seed because I have a greenhouse where I can start them. Later, I transplant them into my garden.
Read my post on how to start seeds in six easy steps if you want to grow plants from seeds.
Many people prefer buying onion sets because it is so quick and convenient. Onion sets are little started onion plants. These can be planted directly into your garden in the spring.
How to Prepare the Soil for Planting Onions
Successfully growing plants really comes down to the soil quality, so don’t skip this important step. Read this post about the Berkeley 18-day method of building compost to learn how to make your own.
We didn’t have our compost piles ready when I was ready to plant my onions, so we bought compost to improve the soil.
Time To Start Onions From Seed – Everything You Need To Know – Long Day Short Day – Sets vs Seeds
FAQ
How long do onions take from bulbs?
What month do you plant onions?
How long does it take a Spanish onion to grow?
Valencia: Valencia is another Spanish-type onion. It has beautiful brown skin and milder flavor than other varieties. It matures in 120 days. Gladstone: Gladstone is a white onion that’s somewhat sweet and suited for northern growing. It matures in 110 days.
How long do onions take to grow?
– Onions grown from **seed** take around 90 to 100 days to reach maturity. – The onion plant takes approximately 90 to 120 days to reach full maturity from planting to harvesting . Remember that growing
How do onions grow?
After the vegetative growth stage, the onion plant enters a phase known as bulb development. During this stage, the plant initiates the formation of its bulb, a part of the onion we use in the kitchen. As the plant continues to grow leaves, the bulb also starts to take shape. The leaves and bulb grow in tandem, complementing each other’s progress.
What happens in the first year of an onion plant?
In the first year, the plant produces bulbs, which are the underground storage structures that we commonly eat. Onions are typically harvested during this first year, as they are in their prime for culinary use and have not yet transitioned to the seed production stage.