Last edited on October 28, 2026. View history
Yellow Onion
A variety of onion
How to sow yellow onion: Direct seed indoors or plant sets (small bulbs) outside.
Sun requirement for yellow onion: Plant in Full Sun
Yellow onions have with yellow skin and white to yellow flesh. They are members of the Allium family along with garlic and leeks. They have a good balance of sweet and astringency in their flavor, and become sweeter when cooked. Spanish onions are a type of yellow onion that is slightly sweeter and more delicate in flavor. Make sure to choose a variety suited to your day length.
- 2
- plantings
- 0
- harvests
- 1
- seed packet
Yellow onion facts
Lifespan
Height × spread
60cm × 13cmRow Spacing
10cmCrop cycle
Max altitude
Optimal light
What are growing degree days?
A plant grows with warmth, not with days. A growing degree day is one day's worth of useful warmth: how many degrees the day's average temperature is above the lowest temperature the crop grows at. Add them up from planting and you know how far along the crop is, whatever the calendar says.
Say that lowest temperature is 10°C. A day averaging 17°C gives 7 growing degree days. A day averaging 8°C gives none, as it is too cold for the crop to grow. That is why the same lettuce takes about 50 days in a summer and 90 in an autumn: it needs the same total warmth either way.
For yellow onion, the FAO EcoCrop database gives a lowest growing temperature of 4°C and a shortest growing cycle of 85 days at its best temperature, about 1233 growing degree days to a first harvest.
Where you've told us where your garden is, we use this and the weather there to predict when your yellow onion will be ready to harvest. We don't use it for how long a plant lives or when it finishes: we go by what members have logged for that.
Growing yellow onions
- Sow seeds in trays 8 weeks before planting out
- Dig compost into the bed 1 week before planting out
- Water regularly at planting out every week
- Weed around the plants 2 weeks after planting out every 2 weeks
- Feed with a nitrogen fertiliser 4 weeks after planting out every month
- Stop watering as the tops fall over 1 week before first harvest
- Lift the bulbs at first harvest
- Dry the bulbs in an airy place 1 week after first harvest
How members grow yellow onions
Sunniness
Planted from
Plant yellow onions with
bell pepper
leek
Video
Where yellow onions grow
Only plantings by members who have set their locations are shown.
What people are saying about yellow onions
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Who's planted yellow onions
- unhackerguard Garden
unhackerguard
Yellow onion harvests
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Time to harvest
If sown now, expect a first harvest in about 85 to 175 days.
From the growing cycle in the FAO EcoCrop database, which is the same wherever it is grown.
Ecological requirements
Data from the FAO EcoCrop database for Allium cepa L.
| Family / Taxonomy | Liliopsida Liliidae Asparagales Alliaceae |
|---|---|
| Life form | herb |
| Life span | biennial |
| Habit | erect |
| Optimal soil depth | medium (50-150 cm) |
| Optimal soil texture | medium, organic |
| Optimal soil fertility | moderate |
| Optimal soil drainage | well (dry spells) |
| Optimal soil salinity | low (<4 dS/m) |
| Photoperiod | short day (<12 hours), neutral day (12-14 hours), long day (>14 hours) |
Learn more about yellow onions
Resources outside Growstuff.
