Square Foot Gardening Onions [Best Tips & Tricks]

Did you know that there are more than 600 onion species? The most common include bulb (aka dry) onions and varieties like leeks, green onions, and scallions.

We’ll break down how you can grow onions with square-foot gardening. Keep reading if you feel ambitious and want to expand your garden this year and include some onion variety.

Also Read: Square Foot Gardening Cucumbers [Helpful Tips]

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What Is Square Foot Gardening?

Square foot gardening is a method for growing crops in individual, one-foot squares. Square foot gardening differs from the traditional row system.

The process, while it may sound complicated, is straightforward. This form of gardening efficiently uses space and resources, meaning you can grow more food in a smaller area.

You create, fill, and separate raised beds into sixteen one-foot squares that form a grid. You can plant different crops in each section, but consider the vegetable’s size.

Square foot gardening works only for smaller crops. Pumpkins and squash would benefit more from traditional gardening.

Square foot gardening makes it easier to tend to your crops without worrying about leaning too far forward, stepping on the bed, or having difficulty planting into the garden.

In short, you plant veggies more densely in a compact space. Square foot gardening is excellent for those new to growing plants or if you don’t want a huge plot to maintain.

Besides, you get a huge variety of fruits and veggies. You can progress your green thumb while being healthier and harvesting produce without GMOs.

Square Foot Gardening Pros

Square foot gardening has several perks. You can grow more compared to traditional rows. Plus, closely planted crops reduce weeds and protect the ecosystem underneath.

This form of gardening is ideal for older people or if you struggle to move around since it doesn’t require much intensive labor.

You can be more vigilant, and you’ll be able to ensure that your plants do well when they’re all in a restricted area.

You can also create a planting schedule to follow throughout the year and successfully grow crops without losing motivation.

If you experience harsh weather, the plot is easier to cover up and save your fruits and veggies.

Overall, square foot gardening systems are easy to set up, perfect for beginners, and less challenging to manage than traditional beds.

Check out: Square Foot Gardening Bush Beans [Best Methods to Grow]

Square Foot Gardening Tips and Tricks

Let’s review some of the basics of square gardening and how this approach is preferable to rows.

Choose the Right Spot

Choose the perfect location for your garden bed in a sunny position sheltered from the wind. You want to have a garden close to your house and near a water supply.

The garden should back onto a vertical structure like a wall or fence. Grow taller crops in the back and the smaller ones in the front.

Reduce Diseases

Grow crops that you, your friends, or your family like to eat. Or plant fruits and veggies that aren’t available at the supermarket.

However, avoid growing veggies from the same family in the same bed. Move it to another bed per year and get healthy crops.

Some plants do well with others, forming relationships that benefit them both. Some plant mixtures create healthy and diverse ecosystems.

Remember that plants with similar requirements do well together and gather nutrients.

For example, onions do well with anything in the cabbage family, like beets, strawberries, tomatoes, and lettuce. Don’t pair onions with beans or peas.

Create Your Own Square Foot Garden

You can make boxes and grids cost-efficiently using reclaimed wood from pallets. Alternatively, you could opt for bricks, blocks, or stones.

Use string to determine each square foot as a visual. You can commit to a permanent layout after measuring the different squares.

Pests and What To Avoid

Pests are always a reality in a garden. Consider birds, rabbits, and other insects that will make a feast out of your garden. You might want to build a barrier to protect crops, like a wire frame.

Maintaining your garden is essential, but you don’t want to take on too much at once, especially if you’re only starting. Avoid trying to grow susceptible crops in northern, cold climates.

Have a look: Square Foot Gardening Kale

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Onion Essentials

Onions grow fast, taking about six to ten weeks indoors. Then, you transplant the onions outside for the remaining time. Onions take between 16 to 18 weeks to grow in ideal conditions.

The perfect onion has thirteen layers or rings, so keep an eye out for that during the prime growing season. The rings correspond to the leaves or foliage.

In other words, the bigger the onion, the more layers it has. A healthy onion will sprout a new leaf every two weeks. Onions are heavy feeders and need nitrogen.

Plant onions as early as you safely can. Once the bulb forms and no more foliage grows, you know your onion is ready.

How To Grow Onions

Let’s take a closer look at how you grow onions. Once you have a foundation, we’ll elaborate on how you can get some delicious veggies out of your square-foot garden.

Here’s a quick pro tip. Keep the tops cut back to 12 or 18 inches. You can eat them (they taste great), and the onion continues to produce more without replanting.

Seed vs. Plant vs. Set

Buying plants is your best bet, even if it’s a bit more costly. Not only does it save you a few extra weeks of growth, but it confirms you’ll have a thriving onion garden.

Sets are what look like small onions, already dried out and experiencing more stress. Often, sets produce a flowering stalk and not an onion.

You can easily grow onions from seed and don’t need much space. For example, ten feet of garden space equals ten pounds of onions.

Seed germination takes an average of seven to ten days. Use pots or planter boxes for growing onions in container gardens.


You can use general-purpose fertilizer as long as the formula has lots of phosphorus. This chemical helps onions develop their roots while potassium levels protect against freezing.

Micronutrients assist growth, so double-check the label for magnesium, zinc, boron, copper, iron, and manganese.

Start with nitrogen fertilizer every two weeks after the onions establish roots. Once a bulb forms, stop using the fertilizer.

The top foot of the soil should be loose with good drainage. Onions thrive in soil with a pH between 6.2 and 6.8.

They benefit from regular, additional fertilizer, so feed your onions after planting. Repeat the process three weeks later with a blood meal or manure.

Continue fertilizing every three weeks throughout the growing season.

Opt for organic fertilizer if you want organic onions. Are you a DIY fan? You can make compost through veggie scraps, wood chips, and manure.


Onions need plenty of water, but avoid watering after the foliage droops. Let the soil dry out before harvesting. Use organic and preventative fungicides often.

Any present spores may increase spoilage and reduce how long the onion lasts. Weed any yellow-tinged leaves; the onions are over-watered.

Check Post: What You Need To Know About Square Foot Gardening Spacing

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Onions require full sun to grow, at least six to eight hours. However, that time depends on your region. Most onions produce bulbs in early spring and are relatively tolerant of light freezes.

Choose onions that do well based on your location in the United States.

  • Short-day onions need a day length between 10 to 12 hours.

Southern states, such as Arizona, Texas, and North Carolina, would accommodate these onions well since they can do well in mild winter climates.

  • Intermediate-day onions require 12 to 14-hour days in the middle regions of the United States. These grow well in areas like Nevada, Missouri, and Virginia.

However, they can also thrive in northern parts of Texas and in North Carolina.

  • Lastly, long-day onions need up to 16 hours of sun. These will grow best in the northern states, such as Oregon, Minnesota, and Michigan.

These can also work in northern parts of Nevada and Missouri, for example.

You can start your onion seeds indoors from October to December. Then, plant the seeds outside and let them grow from October to November.

Then, transplant the onions for their final growing cycle from December to February.

Remember, though, that the earlier you plant, the larger the onions will be. Also, treat your onions well and put some compost into the square when transplanting.


As onions mature, you should see half the bulb above the surface. The lower leaves will wither, or the stems will fall over, so you know the onions are done developing. Ready to harvest!

After you stop watering, leave the onions in the ground for another week or two.

You can remove onions easily since you bury the seeds relatively shallow, only covering the roots. Gently pull on the stems or use a shovel to dig them out.

Cure the onions after harvest. What does that mean? Store the onions in a shady, protected location with airflow.

Organize them in a single layer and keep them there until the skin withers and tightens around the onion. You want the onion to be completely moisture-free and dry.

You also have the chance to discard damaged, bruised, or green onions. (Or, use them immediately). Avoid humid areas to extend the shelf life.

Sweet onions last up to three months but check for soft spots or other signs of decay before it spreads to other onions.

You can dehydrate onions or make onion powder to use your onions in a variety of ways.

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Square Foot Gardening Onions

As we established, row planting isn’t practical. You can grow more with square foot gardening without the extra effort.

The formula for determining how many onions you can fit into one square foot space is easy.

Take the square section of the garden and divide the length and width by the plant spacing needs. You can find the seed spacing number on the back of the seed packet.

We understand that you might feel a little lost after all the measuring and building. Here are the simple steps to follow when making a square foot garden:

  1. Divide the width of the planting section.
  2. Divide the length of the planting section.
  3. Multiply the two answers together.
  4. Now, you have the formula to follow for your entire garden.
  5. Start planting!

Luckily, we’ve done the hard work for you. In general, space onions four inches apart, no more than one inch deep into the soil.

You can generally plant nine onions to a square foot. However, consider the variety before planting.

Look at the chart below to see how much space you need per square based on the onion type.

Onion TypePlant Spacing Per Square
Green Onions16
Onions (bunching)9
Yellow Onion (large)2-4

Read: Square-Foot Gardening Soil Mix [Best Tips & Tricks]

Quick Review: Different Types of Onions

Whew, thanks for sticking with us! Before we finish this article, let’s talk about the different types of onions. There are red, purple, yellow, and sweet onions.

You can eat onions at any stage. Onions are versatile in the kitchen, acting as the base for many savory dishes.

  • Shallots form clusters of divided bulbs. They are intense flavored scallions used for cooking and pickling.
  • You can eat bunching onions fresh, and they produce quickly. You can harvest a batch in a little over two months.
  • Leeks are mild. Cooks frequently use leeks in soups, stews, and salads for a splash of color and subtle flavor.
  • Vidalia onions are big, golden, and sweet. Their taste comes from climate and soil conditions.
  • Sweet onions are common, not overwhelming, and great for recipes during the cold winter months.
Square Foot Gardening Onions
Square Foot Gardening Onions

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Final Thoughts

There you have it! Any good chef knows the importance of onions in cooking. If you want to grow your own, follow these steps for square foot gardening, and you’re sure to find success.

A garden can be a lot of work and effort, but hopefully, we made it easier for you to start this journey and grow yourself a fresh batch of onions.

Once you know the general measurements and how many plants you can plant in your backyard, square foot gardening is simple and effective.