How to Grow Yellow Onions: Growth and Care Guide


Yellow onions are one of the easiest and most popular vegetables to grow in a garden. Not only do they add flavor and flair to dishes, but they also grow quickly and well in most regions.

Read on to discover all of the essential steps in caring for yellow onions, from planting to growing to harvesting your next crop.

How to Choose the Right Growing Environment

Planting and harvesting a yellow onion crop is not a difficult task, as long as the proper planning takes place.

The correct soil will nourish and encourage onion growth while neighboring plants can either inhibit or encourage growth. Timing and spacing are also important. It’s vital to consider all of this information when beginning to plan for growing yellow onions.

What Type of Soil is Best for Yellow Onions?

Making sure your onions are planted in the correct soil will ensure a quick and successful harvest.

Onions need to be planted in a substantial soil depth. If using raised or box beds, provide at least 4 to 6 inches of soil for the onions to grow. In a garden, the onions should be planted 4 inches deep. If the soil is too shallow, the onions will be stunted and may not grow at all.

The soil in the chosen planting area should be:

  • Loose
  • Fertile
  • Well-drained

Onions don’t grow well in soil that is clumpy or claylike. Standing water can cause the roots to rot quickly and will ruin your onions.

How to Choose Companion Plants

Companion plants can help protect your onions; your onions can also protect nearby plants.

There are several options for plants to plant near your onions. This mutually beneficial relationship can increase the output and success of your yellow onion plants. Some good companion plants for yellow onions include:

  • Cabbage– onions repel common pests
  • Chamomile– antifungal abilities protect the onion bulb
  • Carrots– onions repel carrot flies

Plants to Avoid Near Yellow Onions

Some plants just don’t get along. There are various reasons for this. Avoid planting yellow onions near these plants:

  • Pole beans– tendrils can “choke” onion stalks
  • Asparagus– chemical incompatibility causes trouble for both plants
  • Peas– risk of flavor contamination from onions

Onions are generally good companions to most garden plants, except for these few listed above. Make sure to look into specific varieties of whichever plant you are choosing to make sure they are compatible.

Here’s a helpful walk-through video on yellow onions with more info below:

Where to Plant Yellow Onions

Onions grow well in full, direct sunlight. They also do well in raised beds.

It’s important to give the onion plants enough space to grow and mature. Each onion plant should be planted 4 or 5 inches apart, with 12 inches between rows or 6-8 inches between evenly spaced plants if you are planting in a grid.

If you don’t provide enough space between the plants, the onions can be stunted. Additionally, there are more opportunities for weeds and bugs to get into the stalks and cause damage when they are overcrowded. Avoid mold and fungus development by spacing the stalks apart.

How to Plant Yellow Onions

Onions can be grown from either seeds or plant starts, and whichever method you choose will impact the timing and length of the harvest substantially. (source)

Growing Yellow Onions from Seed

Yellow onions grow well from seed, but they need to be started indoors. Seeds should be planted and have time to grow inside for 8-10 weeks before the last frost date in your region. There are handy maps available to identify these dates.

The seedlings should be transplanted outside after about 4 weeks of hardening off. Water and fertilize the soil after transplanting.  Transplanted onions need to be watered immediately.

Yellow onions will mature five months after the seeds are planted.

Growing Yellow Onions from Sets

Choosing to plant onion sets will be a quicker harvest time, and the danger of transplant shock is decreased.

Plant the onion sets directly into the ground with the pointy end up, as the roots will grow from the rounded end.

Yellow onions are ready for harvest about two and a half months after the sets are planted. (source)

How to Ensure you are Providing Correct Care

Yellow onions that are growing and healthy will display:

  • Strong, upright stalks
  • A dark green, consistent stalk color
  • No large marks or extensive damage to the stalks

Conversely, illness and trouble with your onion can be identified by:

  • Wilting stalks
  • Discoloration or visible mold
  • Halted growth before maturity

Below are a few more steps to take to encourage maturation and healthy growth of your yellow onions.

How Much Water Do Yellow Onions Need?

Yellow onions require a substantial amount of watering. Roughly 30” per growing season is recommended.

If the onion tops become cracked or the soil around the bulbs appears dry, they need more water. If the stalks become a yellowish color, they are being overwatered.

Avoid watering directly overhead (like with a hose). This can damage the stalks. Instead, water directly onto the soil or use irrigation hoses or deliver water at the base of the plant. (source)

When the onions are ready to be harvested, watering should cease immediately in order to let the soil dry out right before harvesting.

How to Harvest Yellow Onions

After all the hard work of planting, cultivating, and nourishing your yellow onions, the harvest can be the most exciting part. Removing your onions from the soil correctly is important for their longevity.

When to Harvest Your Yellow Onions

Your onions will be ready for harvest in mid to late summer. The stalks will fall over and wither even with regular watering. Often, you’ll be able to see the top of the onion bulb popping out of the soil.

Make sure to harvest these quickly. If it rains, the ripe onions can rot easily. It’s also important to harvest the onions in the morning before the temperatures are too hot. The roots will dry out better if it is a gradual heat increase and not a shock from damp soil to high temperatures.

The onions can be pulled straight up out of the soil by firmly grasping the stalks in your hand.

How to Store Harvested Yellow Onions

Once the onions have been pulled from the soil, it’s important to follow a few steps for optimal storage and preservation.

First, lay the onions in a single layer on some newspaper or cardboard with a few inches of space in between each. Ensure they are in a warm but ventilated area, a garage in summer or a table on a covered patio usually works well. If outside, monitor for cool weather and rain.

After a few days, the onions will have “cured” and the outer skin will appear just how they are found at the grocery store. The skin should be:

  • Papery
  • Dry
  • Flaky

The stringy, dried roots can be rubbed off. Be careful not to damage the actual body of the onion. The tops can also be left on and braided or twisted, or removed. If removing the stalks, leave a few inches, so you don’t damage the top side of the onion.

Hang your cured onions in bunches by the stalks or in mesh bags. Keeping them in a cool and dry place is best. They will stay good for months. The ideal temperature for storage is 50-60 degrees.

Make sure to avoid moisture whenever the onions are stored. This can cause rot. Yellow onions are incredibly versatile and an important ingredient in many recipes and cuisines from around the world.

Robert Sampson

I'm Robert Sampson and I live in Colorado where I spend a lot of time in the backyard with my family either grilling, playing games and sports, or working on a project to make our backyard a better place to be.

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