how to make onions grow bigger

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If you are looking for tips on how to make onions grow bigger, you are in the right place. I have easy things you can start doing right away to increase the size of your onions at harvest time.

Gardening 101 tips that you can try out with your own backyard vegetable garden.

how to grow bigger onions

Working all summer long to grow onions only to harvest small bulbs is a struggle for many gardeners. I had issues myself for many years and that’s when I went looking for ways to help my onions grow larger before it was time to harvest.

We will look at tips you can use when planting, how to water more efficiently, what issues to watch for, and when to harvest. By the end, you will have a game plan that you can use in your next growing plan.

Be sure to grab the FREE Grow Bigger Onions Checklist below!

When do onions need to be planted?

Onions require a long growing season and that means they will need to be planted before most, if not all, of your other plants. If you live in the Northern Hemisphere, it is best to plant onion bulbs in early spring. However, if you are living in the Southern Hemisphere, you can plant them between March and June giving you plenty of time for them to grow adequately.

large onions out drying in the sun after being picked from a garden

A tip I like to give for anyone that lives up north, as soon as you can work the ground, that is a good time to plant your onions. If you are not sure if your time is too early, you can test the temperature of the soil before planting. Look to plant when the soil reaches around 50F.

How to Make Your Onions Grow Bigger

One of the biggest reasons why your onions may not be as big as you want them to be is that you are not giving them enough growing time. Onions are slightly different from other vegetables because they need more time in the ground. For this reason, you will want to plant them early in the season. See the tip above for when to start planting.

#1. Choose the Right Location

Onions thrive in full sunlight; make sure you choose a location that receives 10 or more hours of sunshine daily. Avoid planting them in shaded areas, as this can affect their growth. This includes planting them near to other vegetables that many block out the sun such as vining plants that can take over the garden or plants on a trellis that can shade other areas.

#2. Prepare Your Soil

Onions need well-drained soil with enough space for their roots to grow deep. If your soil is clay, add some compost or peat moss to loosen it up. On the other hand, if your soil is sandy, mixing in some organic matter will help retain moisture.

READ: How to Set Up a Backyard Compost Area

#3. Plant Your Onion Bulbs

When planting your onion bulbs, make sure that you place them about an inch deep into the ground with their tips facing upwards. Space them about 4-6 inches apart to allow enough room for the bulbs to grow.

#4. Plant Onions in Raised Rows

One of the biggest issues I deal with is overly wet soil and this is something onions do not do well in. To help, we plant in raised rows and have found this really helps with drainage. This one tip greatly increased the size of our onions.

long raised rows in a garden waiting to be planted with onion bulbs

If not enough moisture is an issue, you can add a layer of mulch on top of the soil to help retain moisture.

#5. Watch your spacing

If onions are planted too close together, they will compete for sun and nutrients. For bigger onions, you will want to space them adequately apart. Aim for 5″ apart from the next onion planted. This can be hard to do in the beginning, but trust me it will matter in the end.

#6. Keep Weeds Out

Because onions have shallow root systems, weeds can easily affect their growth. To help, be sure to weed routinely starting early on. Mulch is your friend when growing bigger onions. Adding a layer of newspaper with cut grass or straw on top works great to keep weeds from taking over.

rows of onions planting with straw mulch inbetween

Be careful when weeding around young onion plants, as it can damage the roots if you are not careful. To help, gently put a finger at the base of the onion plant as you remove any weeds with your other hand. Giving that bit of support to the base will help keep your onion plant in place.

#7. Water Regularly

Onions require consistent moisture to grow well, but make sure not to overwater them as this can cause rotting. A good rule to follow is to water them deeply once a week. If you live in a dry climate, consider using drip irrigation or soaker hoses.

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#8. Fertilize Sparingly

Onions don’t require much fertilization, but you can use a balanced fertilizer once or twice during the growing season. Avoid using nitrogen-heavy fertilizers as they can result in more foliage growth rather than bulb development.

#9. Harvest at the Right Time

To get bigger onions, it’s essential to harvest them at the right time. Here is a good routine to follow:

onions drying on a board in the sun
  1. When about half of the onion tops have fallen over, harvest in teh morning on a warm sunny day.
  2. Gently lift them out of the ground laying them in place.
  3. Let them stay here for the day so the soil can dry.
  4. Later in the afternoon shake the soil off the onions and gather them up.
  5. Put them on a table or you can use a tray to let them cure for about a week.
  6. Once done remove any remaining soil and trim both ends.
  7. Store in a dry cool area or dice and freeze for later use.

Growing big onions is easier when you know what they need to thrive. Following these tips and taking proper care of your onion plants, you can ensure a bountiful harvest of delicious and healthy onions that are bigger.

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