How To Grow Red Onions

Onions are a staple ingredient used all over the world for their versatile use and added flavor. They are ideal for growing at home and make the perfect addition to your garden providing you with a consistent supply from your garden to your kitchen.

One of the best varieties to grow is red onions. They are sweeter, full of flavor, and provide a deep purple color to your homemade dishes. Not to mention they are relatively easy to grow and have a longer storage life than yellow onions.

However, as they are a biennial plant, you do need to take into consideration the time it will take to grow red onions, and whether you want to plant seeds or sets.

Keep on reading to find out top growing tips and how to grow red onions from sets and seeds.

how to grow red onion pin

Top Tips To Grow Red Onions

  1. Plan In Advance

Red onions are a biennial plant which means they can take 2 years to grow and produce onions you can harvest. In the first year, the seeds are focusing their energy on generating a bulb. It isn’t until the second year that they then begin to grow the vegetable suitable for harvesting.

If you are wanting to harvest red onions the same year you plant them, you are best starting with sets. These are onion bulbs already established in their second year of growth. They will produce the vegetable during the same growing season.

However, if you can wait, you can begin to grow red onions from seeds. Yes, it does take longer to grow but will be even more rewarding.

Alternatively, why not consider planting both. Your sets will be ready the same year as planting and able to be harvested, while your onion seeds will be ready to gather the following year.

  1. Prepare the soil

Onions require a lot of nutrients plus the right pH level to grow. Make sure to turn your soil with high-quality, organic compost before planting your onions. If possible, add fertilizer at this stage and also at the level your onion bulbs will develop.

You can also check your soil’s pH levels ensuring it is between 6.0 – 6.8 and adjust accordingly.

  1. Resources

Red onions grow well in areas with access to full sunlight for at least 8 hours a day. They also require regular watering but ensure to check how wet the soil is first. Too much water will lead to root rot.

And finally, be sure to remove weeds around your onions. They will compete for space and resources such as sunlight and can prevent your onions from growing.

How To Grow Red Onions

Growing red onions does require time due to being a biennial plant, however, they are easy to grow and need little maintenance.

growing red onions

They can be grown either from seeds or sets. Seeds will take 2 years to produce your crop, whereas your red onions will be ready to harvest the same year as planting your sets.

Growing Red Onions From Seeds

The red onion needs planting indoors 8-10 weeks before the last frost. They need to be planted at least 0.5-1cm deep in individual containers. Within 4-10 days, the seeds will begin to germinate.

When the last frost has finished, you need to dedicate time to preparing the soil. Check its pH level, add fertilizer and compost, and turn the soil to improve drainage.

The seeds can be planted outdoors in a sunny area. They need to be planted at least 2 inches deep and 6 inches in space between each plant. Red onions are best planted in rows to help maintain them over the next two years, so try to leave 12-18 inches between each row.

After they have been planted in the ground, it will be two years until they are ready for harvesting.

Over the next two years, you need to spend time keeping the area free from weeds. You also will need to water your onion plants at least twice per week. If you aren’t sure whether your onions need watering, check the first couple of inches of soil with your finger. If it feels dry, your red onions need watering.

Growing Red Onions From Sets

Onion sets are simply small, partially grown bulbs. They have already been through a year of growth from seeds and need the following year to produce a larger bulb.

If growing red onions from sets, spend time choosing the more significant sets to plant. Larger sets will lead to bigger red onions.

Sets are best planted between March and April, although some varieties are cold resistant and can be planted between October and March.

Similar to planting seedlings, you need to prepare the soil before planting your red onion sets, and select an area that has access to direct sunlight.

Each set needs planting with just the tip showing above the soil. They need at least 2-4inches of space between each plant and rows to be planted 10-12inches apart.

Your red onion sets will be ready to harvest from mid-summer to late Autumn depending upon when they were planted.

red onions growing


Can you grow red onions from an onion?

Yes, you can! Once your onions have sprouted in your kitchen, you can prepare them to be planted outdoors to grow new onions.

First, peel and remove all the outer layers of the onion until you get to the inner sprouts. Then, remove the thinner layers to reveal each sprout. Often, each onion will generate up to 3 new sprouts. Separate each sprout carefully with a knife and plant it in the garden with the leafy tops out of the soil. They will take approximately 3 months with the right care to grow.

How long does it take for red onions to grow?

As they are a biennial plant, red onions can take two years to grow from seeds. In the first year, the onions are focusing their energy to develop into a bulb. In the second year, the bulb is maturing and grows larger.

Do onions grow back every year?

Onions take 2 years to grow before they are ready to harvest. As they are not perennial plants, they will not regrow again following years. However, from your harvest, you can leave some of the onions to sprout and replant them.

What grows well with red onions?

Several other crops make excellent companion plants with onions including tomatoes, strawberries, and dill. Take a look at this post to read more on what you should and shouldn’t plant with onions.

red onions ready for harvest

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