Red onions are one of the most common onion varieties used in culinary dishes aside from yellow onions. It’s a prized choice because of its mild, sweet flavor and gorgeous color, but too many gardeners shy away from learning how to grow and harvest red onions.
Red onions aren’t difficult to grow. Regardless of the type of onion that you grow, all onions are biennials, which means it takes two years to complete their life cycle. In the first year, the seed grows and forms tiny bulbs. Then, in the second year, the bulbs mature.
Red onions are just as easy as yellow and white onions to grow. They don’t require any special treatment or care, so if you’ve grown one type of onion, you can grow them all. Let’s learn how to grow and harvest red onions in your garden this year.
Red Onion Varieties to Grow
Before you learn how to grow and harvest red onions, you want to pick the varieties you would like to grow. Make sure to look at the days to maturity and compare it to how many days you have in your growing season.
Here are some popular red onion varieties.
This is a unique variety that has pinkish-red skins and an elongated shape. Italian Torpedo onions are a long-day cultivar that has a sweet, mild flavor. These onions take around 110 days to reach maturity.
Here is a short-day globe onion that produces three to four-inch bulbs with red rings and dark red skins. Red Burgundy is an heirloom onion with a mild and sweet flavor, and if you struggle with pink root disease, these onions are resistant.
Southport Red Globe
If you want a storage red onion, try the Southport Red Globe. It’s an heirloom, long-day onion that produces large bulbs that have purple skins and pink flesh. These onions are ideal for Northern gardeners; they need around 100-120 days to reach maturity.
How To Grow Red Onions From Planting To Harvest
While onions are biennials, they’re hardy in USDA zones 5 through ten. You can grow red onions in the spring, summer, or winter in areas with mild climates. If you want to add red onions to your garden, here is our planting to harvest guide to red onions….
1. Amend The Soil For Onions
One of the keys to growing red onions is to give them a good start with the best soil possible. The soil should be well-draining; standing water will cause the bulbs to rot.
To start your onion bed off properly, make sure you use a hard rake or hoe to loosen the soil. Remove all rocks and weeds as well. Root crops need loose soil to grow down into the ground.
2. Plant Them In The Right Spot
Red onions need plenty of sunlight to grow properly. They grow best when they receive six to eight hours of sunlight per day.
Look for a location that doesn’t have clay soil. If the spot you have available is clay, you’ll need to consider using raised garden beds or rows to create the fluffier soil.
3. Starting Red Onion Seeds
Growing red onions can be done either by growing seeds or growing red onion sets. While onion sets are easier, onion seeds are an economical choice for gardeners, but growing red onions from seeds takes plenty of patience.
4. Planting Red Onion Sets In Your Garden
Most gardeners prefer to plant red onion sets rather than starting seeds because it’s much faster. Remember, it takes a full year for the seeds to create a bulb. So, if you don’t use sets, you’ll wait two years to harvest; using onion sets helps you reach maturity faster.
How to Care for Red Onions
Red onions don’t require too much special care compared to other vegetables, but there are a few things you should remember about caring for these plants in your garden.
1. Consistently Water Your Red Onions
Red onion roots are shallow when compared to other vegetables, so they need a consistent supply of water. The roots are closer to the surface rather than deep down. If the top few layers of soil are dry, then it’s time to water.
2. Spread A Layer Of Mulch Over Your Red Onions
Spreading a layer of mulch around your red onions can help retain some of the moisture needed, which means you have to be waterless.
3. Watch For Weeds
Weeds compete with your onion plants, so they’re a no-go in the garden. You need always to pay attention to weed growth because they will take away any nutrients in the soil that you added for your onions.
How And When to Harvest Red Onions
Waiting all of the months to harvest your red onions can feel like an eternity, but it’s what you’ve been waiting for this whole time! You might start to wonder when to harvest red onions.
After a few weeks, you can pull red onion greens and use them as scallions in your recipes, but full-size red onion bulbs do take months to grow and mature. Depending on when you planted the sets, your red onion bulbs should be ready between late August and early October.
Red onions are ready for harvest when the bulbs are large, and the green tops start to yellow and fall over.
As the red onions dry and start to cure, the roots shrivel up, and the necks dry. Curing takes seven to ten days.
At that point, you could either braid the tops for easy storage or remove the tops with shears and store them in a cool, dry place. Red onions store the best when in a location between 35-50℉.
Common Pests & Diseases That Bother Red Onions
While red onions might be easy to grow, that doesn’t mean they aren’t without their problems. Pests and diseases love onions, so you have to battle them back. Here are some of the most common pests and diseases that you might find in your onion patch.
One of the most common fungi that could bother your red onion plants is downy mildew. If your onion stems are constantly wet, the fungus can develop; it loves moist areas without much air circulation.
You’ll know that your onions have downy mildew because the stems start to turn grey and produce a strange, fuzzy growth. You can cut away the affected areas to save your plants.
If you find trails of holes throughout your leaves, you might have leafminers. Heavy infestations can result in white blotches on the leaves and the leaves dropping from your plant prematurely. An early infestation might reduce your yield.
Leafminers are a small black and yellow fly that lays their eggs on the leaves, and then the larvae hatch and feed on the leaves.
Ensure you remove your plants from your garden after harvesting so that they don’t have a space to grow and populate in the winter and spring. It’s best to avoid spraying with an insecticide until the infestation is heavy; you can try neem oil as an organic spray.
No one likes dealing with mites. They can cause your plants to have stunted growth, and the bulbs might rot in the ground or storage.
Mites are tiny pests, measuring less than one millimeter in length. They’re creamy-white, looking like small pearls with legs. It’s essential to take care of the problem because a mite infestation will make your plant vulnerable to pathogens and bacteria that could kill it completely.
Some people find that neem oil is an effective way to treat mite populations.
If you notice stunted or wilted seedlings, you might have onion maggots. These pests can cause the plants to break in the soil if you try to pull them out. If the infestation happens early, you’ll find that the bulbs are deformed and unable to store for long periods.
Onion maggot adults are a grey fly that lays white, elongated eggs around the base of your plants. The larvae that emerge will bore into your plants.
Managing onion maggots does rely on adequate sanitation; make sure to remove all onion bulbs at the end of the growing season because maggots use them as a food source in the winter. You can try insecticide sprays or use floating row covers when you plant the onions to stop the adult onion maggots from laying eggs on the plants.
Onion Neck Rot
Caused by the botrytis allii fungi, this is another common problem that onion plants experience. If you see a fuzzy, grey fungus growing on your onion’s head, you have onion neck rot. As it progresses, the onion’s head will rot and turn black.
It’s hard to treat onion neck rot once it sets in, but this is one reason why rotating your onion crops is essential. Make sure you always plant your onions in different places each year.
If you find light pink roots that darken and turn purple, you have pink roots. Over time, the roots become transparent and water-soaked, and it might look like your plants have a nutrient deficiency. The affected plants might experience stunted growth.
The pink root is caused by a fungus that is absorbed through the root tips. It can live deep down in your soil. This disease is most severe when onions are planted in the same area continuously, so you must rotate your crops. You also can plant disease-resistant varieties.
This fungus causes small, water-soaked lesions on the leaves or stalks of your plant with white centers. Over time, those lesions grow and turn brown to purple. Some of the larger lesions can kill the tissue between them, and severely infected plants will die.
This disease tends to pop up when the foliage continues to stay wet and the nights have high humidity. Gardeners need to make sure they don’t water in the evening and space the plants for proper air circulation.
You can try applying an organic fungicide if your plants have purple blotch, but it may not work. The most effective defense is rotating crops and letting them dry out during the day.
Growing Red Onions
If you’ve grown white onions, you can surely learn how to grow and harvest red onions. They grow and harvest the same, and they aren’t any more complicated than white or yellow varieties. Red onions have a mild, sweet flavor that makes them an excellent addition to your garden.
Bethany is a suburban homesteader, growing over half of the vegetables, fruit, and herbs that her family of six needs each year. She raises chickens and homeschools her children. When she isn’t spending time tending to her garden, you can find her reading, crocheting, and canning.