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Growing Onions at Home – Planting Onion Sets – Harvesting Onions

Onions are a vegetable that I use almost every day in recipes. Growing onions at home is easy, as long as you have a sunny garden spot and a patient nature.

Onions are a cool weather crop. Get started early on your planting and you will be enjoying fresh onion bulbs by the middle 0f summer.

Growing your own onions gives you a whole new taste sensation compared to using grocery store onions. They take up little space, so they can be grown indoors or raised garden beds as well as normal vegetable gardens.

Never tried to grow onions? Grab a cup of coffee and get ready to learn all about growing onions from sets, when to plant onions and how to harvest onions.

Onions growing in a field.

Should I grow onions from seeds or sets?

The answer to this question depends partly on your growing season length.

I normally prefer starting onions from sets, because the sets start growing quickly and are much easier to plant.

Onions are so versatile in recipes. They are also very easy to grow, even in containers. Find out more about growing onions from sets on The Gardening Cook.🧅🧅🧅 Click To Tweet

What are onion sets?

Onion sets are basically very small dormant onion bulbs that are sold for onion growing. Once you plant these tiny bulbs, they develop into a full-size bulb in about 90 days or so.

Three types of onion sets with garden tools.

A benefit of onion sets is that you don’t need to worry about frost damage after planting. Sets also have a good success rate compared to onion seeds.

Another thing to consider is the type of onions that you plan to grow. There are short day onions, intermediate day onions and long day onions.

Short day onion sets develop buds when the day length in 10-12 hours per day. Intermediate day onions bulb up when the day length is 12-14 hours long. Long day onions require 14-16 hours of daylight to grow bulbs.

Choose short day onions for southern gardens located between 25-35 degrees. They’ll start producing a bulb when the day length is 10-12 hours.

Short day onions are sweeter but long day onions store better so the choice is yours, and that of  your location.

Many gardeners plant short day onion sets in fall and long day onion sets in spring.

What is the best month to plant onions?

Because of their long growing season, onions should be planted in the spring. In areas which have mild winters, onions are often planted in the fall.

As a rule of thumb, plant onion sets outdoors when the weather is cool but not cold. Early spring planting is good for cooler zones. Late fall, about 4-6 weeks before the really cold weather, works well for warmer zones.

Fall planted onions usually produce a larger bulb harvest since the roots have a good chance to develop before the cold sets in. This type of crop goes dormant in the winter and comes to life again in the spring.

It is normal for onions to grow top parts in cool weather and to form bulbs when the weather warms up.

Growing onions from seeds

Even though I prefer to grow onions from sets, it is possible to grow them from seeds, as well.

Onion and seeds

It is normal to start onion seeds indoors about 6 weeks before you plan to transplant them into your garden. Onion seed require temperatures of at least 50°F (10°C) in order for them to germinate. 

Planting onions

These tips for growing onions are for normal bulb onions grown from sets. I also have a post about growing spring onions that you may be interested in reading.

Choose a spot that gets full sun. Onions need 13-16 hours hours of sunlight a day to develop large bulbs. Be sure that the onions are not shaded by other plants.

Generally speaking, the more sunlight onion plants get, the larger the bulbs will be.

Be sure the soil drains well. To ensure this, add compost or other organic matter to your soil before planting onion sets or seedlings. Onions like a nitrogen rich soil for optimal results.

As soon as the ground can be worked in the spring, plant your onion sets. The sets are planted about 1 inch deep in rows about a foot apart. Don’t bury the sets too deeply or this could affect how the bulb forms.

Hands with gloves planting onion sets.

Plant the sets with the pointed end facing up. Cover with soil and water well. Once the bulbs have started to develop, mulch to retain water and prevent weeds.

Onion plants are heavy feeders. Adding compost before planting helps but extra fertilizer every few weeks is also needed throughout the growing season. Stop fertilizing when you see the bulb start to surface.

Water when the weather is really dry. Onions can look healthy even if they really need watering. If you don’t maintain a good watering regimen, the onions may bolt. Onion plants need about 1 inch of water each week.

It is a good idea to practice crop rotation with onions and other vegetables. This helps to keep your crops disease-free.

How long do onions take to grow?

Onions love cool temperatures. They require about 90 -120 days to reach maturity, depending on the type.

If the growing season is short in your area, it may be difficult for onions grown from seeds to have bulbs to reach maturity before the warm temperatures to arrive. 

Onion sets will produce earlier onion bulbs. The time saving is considerable – you can have bulbs growing from sets in 40-60 days – about half the time as seed started onions.

Why are my onion bulbs small?

Generally, if your onions are small when it is time to harvest, there are a few reasons.

It is possible you are not growing them in a spot with enough sunlight.

small onions with green tops.

Another reason for small onion bulbs is that you plant them too late. Remember that most onions have a long growing season.

Companion plants for onions

We refer to companion plants as those that have similar growing habits and other complimentary characteristics such as nutrient requirements, sunlight needs and pest-repelling traits.

Vegetable garden with onions and words companion plants for onions.

Some good companion plants for onions are:

As well as plants that can be good companions, there are also some plants to avoid. Keep onions away from these plants:

Can I plant onions with garlic?

This is a common question from readers of my blog. While planting onions and garlic together doesn’t affect either plant in a dramatic way, it is common to plant them near each other because of their impact on other crops planted around them.

All members of the allium family (of which onions and garlic are members) will repel many types of mites and grubs.

Harvesting onions

All types of onions can be used as scallions when they are young. Add them to fresh salads or in stir fries for a mild onion flavor. 

Onions are starting to mature when the foliage gets yellow and becomes droopy.

Hands preparing onions for storage.

If any of the onions send up flower stalks, pull them up. This is bolting and means the bulbs have stopped growing. Use any bolted recipes quickly since they don’t store well.

Loosen the soil around the onions so that they will dry out a bit. Wet onions have a tendency to rot when stored.

When the tops are brown, harvest the onions. Take care not to bruise onions when you harvest them. This can lead to rot in storage.

Onion bulbs will need to dry for a few weeks before you store them.

Can you grow onions from an onion?

Onions are normally grown from sets. However, you can also use parts of an onion to grow new onions.

This is an ideal thing to do when you use the top part of an onion in the recipe. Make a new onion from the bottom!

Onions are a root vegetable. If you chop off the bottom of the onion which has the roots on it and plant it in soil, you can grow a new onion.

Onions sprouting from onion bottoms.

You can either use the entire onion bottom to grow a new onion, or you can divide the root area into several pieces and it will grow into new onions.

The onion will sprout and grow onion tops in just a few days. You can use these in salads, or like you would spring onions. Alternatively, you can allow the onion part to grow into a new onion bulb.

Give the root cutting plenty of water and you’ll have a new onion in 90-120 days. 

Can you plant onions indoors?

Onions need lots of sunlight to develop bulbs. Spring onions are a good choice if you would like to try growing them indoors. Bulb onions take up more room.

Also, spring onions easily re-grow indoors.

Growing onions vertically in a large soda bottle is a fun project to do with kids.

Onions growing indoors.

Admin note: this post for growing onions first appeared on the blog in April of 2013. I have updated the post to add all new photos, a printable recipe card, and a video for you to enjoy.

Pin these tips for growing onions at home for later

Would you like a reminder of this post for how to grow onions from sets? Just pin this image to one of your gardening boards on Pinterest.

onion sets in a box with garden tools and words "growing onions from sets."

How to make onion rings without flour or bread crumbs

It is time to use the onions you have been growing all season. Why not try these onion rings that use rolled oats and are then baked in the oven? They have all the flavor of the deep fried version of the dish, but are much more healthy.

These onion rings have a crispy texture and are super tasty. The flavor comes from the nice combination of spices and seasonings used in the coating mixture.

Egg whites and almond milk help the seasonings to stick to the onion rings and ground rolled oats adds a health boost to the recipe.

The end result is – a nice crunchy and savory onion ring that makes a great side dish or appetizer course for a party.

Yield: 2 servings

Baked Onion Rings Recipe

Baked onion rings in mayonnaise.

These oven baked onion rings have all the flavor of deep fried ones but are much more healthy. They are made with oats instead of flour for an added healthy touch.

Prep Time 5 minutes
Cook Time 25 minutes
Total Time 30 minutes

Ingredients

  • 1 vidalia onion, sliced
  • 1/3 cup of rolled oats
  • 1/4 teaspoon of black pepper
  • 1/4 teaspoon of crushed red pepper
  • 1/4 teaspoon of garlic salt
  • 1/4 teaspoon of seasoned salt
  • 1/3 cup unsweetened almond milk
  • 2 egg whites
  • Pam cooking spray

Instructions

  1. Preheat the oven to 450 degrees.
  2. Meanwhile, put the oats into a food processor and pulse to grind it into a flour consistency.
  3. Combine the spices with the ground oatmeal and set aside.
  4. Mix the almond milk with the egg whites in a separate bowl.
  5. Peel the onion and slice it and then separate it into rings.
  6. Place each ring into the milk solution for a few seconds and then roll in the oat flour mixture.
  7. Place on a baking sheet lined with parchment paper.
  8. Spray with Pam cooking spray.
  9. Cook for 20-25 minutes (watch to make sure the onion rings don't get too browned.) Turn halfway through and spray with Pam again.
  10. Serve with your favorite dipping sauce.

Notes

A note on gluten free:

Most oats are gluten free, but may be made in factories where cross contamination can occur. Check your label to make sure the oats you use are certified gluten free.

Nutrition Information:

Yield:

2

Serving Size:

1

Amount Per Serving: Calories: 128Total Fat: 2gSaturated Fat: 0gTrans Fat: 0gUnsaturated Fat: 1gCholesterol: 0mgSodium: 457mgCarbohydrates: 23gFiber: 3gSugar: 9gProtein: 7g

Nutritional information is approximate due to natural variation in ingredients and the cook-at-home nature of our meals.

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