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The commononionis a biennial bulb with hollow, tubular, blue-green leaves.
so that thrive, onions need lots of sunlight, well-draining soil, and nitrogen-rich fertilizer.
Sunny spots with loose soil and a neutral pH are best.
The Spruce / K. Dave
If you’restarting with seedlings, plant them outside when the soil temperature is around 50 degrees Fahrenheit as well.
Its also possible to plant in the fall in warmer climates.
The onions will stay dormant over the winter and then continue to grow in the spring.
The Spruce / K. Dave
Selecting a Planting Site
Choose a sunny spot with loose soil.
Compacted or rocky soil will hinder bulb growth.
Also, avoid planting where otherAlliumspecies have been in the past few years.
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Pests and diseases that target the plants can linger in the soil.
Container growth is also an option if you don’t have proper garden conditions.
Space the sets roughly 4 inches apart, and space rows 12 to 18 inches apart.
The Spruce / K. Dave
Once the sets are in the ground, leave them alone; do not hill soil up around them.
The sets are supposed to peek out of the ground at all times.
Plant seeds only about 1/4 inch deep.
The Spruce / K. Dave
And thin seedlings to around 4 inches apart also in rows that are 12 to 18 inches apart.
A support structure generally won’t be necessary.
With onions, the more sunlight the better.
Soil
Proper soil is the key element to growing onions successfully.
The soil needs to be extremely well-drainedeven sandyand it should have lots of organic matter.
A loose loam will work well.
And a soil pH that hovers around neutral to slightly acidic is best.
Water
Onions need regular water to support the swelling of the bulbs.
Give them 1 inch of water per week.
A light layer of mulch can help to retain soil moisture.
Temperature and Humidity
Onion seeds need temperatures of at least 40 degrees Fahrenheit to germinate.
The optimal growing conditions for onions are between 68 to 77 degrees Fahrenheit.
Humidity typically isnt an issue as long as soil moisture needs are met.
Fertilizer
Onions are fairly heavy feeders.
Fertilize them every few weeks with a high-nitrogen fertilizer to support leaf growth, which will produce big bulbs.
For the amount to use, follow the product label instructions.
Pollination
Most gardeners grow their onions as annuals and harvest before flower stalks appear.
Bees and other insects, as well as the wind, serve to pollinate onion flowers.
But when buying mail-order seeds, confirm tochoose the right varietybased on your climate.
Plus, they require similar growing conditionsespecially loose, nutrition-rich soil.
However, garlic bulbs generally mature at a much smaller size than onions.
A garlic bulb also is a group of tightly packed cloves while an onion is many layers of leaves.
But you canharvest onionsat any stage; even seedlings thinned from a row can be used asgreen onions.
Its best to harvest in dry weather.
Then, allow the bulb to sit in the ground and cure for a couple of days.
Next, dig up the bulb, rather than pulling it.
You dont have to dig deepjust enough to loosen the remaining roots.
Brush off any loose soil, and trim the leaves to about 1 to 2 inches from the bulb.
Also, trim off the roots.
Then, hang them in a mesh bag in a cool, dry spot with good air circulation.
The temperature should be roughly 40 to 60 degrees Fahrenheit.
However, dont store them in a refrigerator as that environment is too humid.
Check regularly for signs of rot, and remove any culprit before it can impact the other onions.
Choose a container thats roughly a foot deep.
Its also essential that the pot has drainage holes.
Unglazed clay is a good container material to allow excess soil moisture to evaporate through its walls.
Pruning
Onions generally don’t require pruning.
However, be sure to remove any damaged leaves promptly.
If they’re left to drag on the ground, they can introduce diseases or pests to the plant.
Propagating Onions
Besides growing from seeds and sets, you also can propagate an onion fromscraps.
This is a great way to stretch your harvest and get more out of what wouldve been waste.
The best time to start this process is in the early spring.
Place the tray underartificial grow lightsfor 10 to 12 hours each day.
Keep the potting mix damp but not soggy.
When outdoor temperatures are routinely above 50 degrees Fahrenheit, transplant the seedlings into the garden.
Potting and Repotting Onions
Use a quality organic vegetable potting mix with sharp drainage for potting onions.
you’re able to mix in some compost to improve the drainage and nutrient content.
Overwintering
Because onions are typically grown as annuals, overwintering won’t be necessary.
If you’re planting a fall crop in a warm climate, consider raised garden beds.
They will help to keep the temperature more consistent for the dormantonions throughout the winter.
Common Pests and Plant Diseases
Pests and diseases that afflict otherAlliumspecies also can impact onions.
Try growing from sets first, as they tend to have a good success rate.
Onions are biennial, meaning they complete their life cycle in two growing seasons.
