Tips for Growing Walla Walla Onions

Are you ready to embark on a journey that will elevate your gardening skills to new heights? Get ready to unlock the secrets of growing the luscious and flavorful Walla Walla onions. Whether you’re a seasoned horticulturist or a beginner with a green thumb, this article will provide you with expert tips and proven techniques to cultivate these legendary onions right in your own backyard.

In the first paragraph, we’ll explore the rich history and unique characteristics of Walla Walla onions, giving you a taste of what makes them so special. From their sweet and mild flavor to their crisp and juicy texture, these onions have rightfully earned their place as a culinary delight. The second paragraph will delve into the practical side of growing Walla Walla onions, providing valuable insights into soil preparation, planting techniques, and essential care. With step-by-step instructions and insider knowledge, you’ll be equipped to nurture your onion crop from seed to harvest, ensuring a bountiful yield that will make the mouths of your friends and family water. So, let’s roll up our sleeves and begin this exciting adventure, unlocking the secrets of growing Walla Walla onions!

Choosing the Right Location

Sunlight Requirements

When choosing a location to grow Walla Walla onions, it is important to consider their sunlight requirements. These onions thrive in full sun, which means they need at least six to eight hours of direct sunlight each day. Therefore, it is crucial to select a spot in your garden that receives ample sunlight throughout the day. Avoid areas that are shaded by trees or buildings, as this can result in stunted growth and smaller bulbs.

Soil Quality

Another key factor to consider when choosing a location for your Walla Walla onions is the quality of the soil. These onions prefer well-drained soil that is rich in organic matter. Before planting, it is recommended to conduct a soil test to determine the pH level and nutrient content of your soil. Walla Walla onions prefer a slightly acidic soil with a pH ranging from 5.8 to 6.8. If your soil is too acidic or alkaline, you may need to make amendments to adjust the pH level accordingly.


Good drainage is essential for the successful growth of Walla Walla onions. Waterlogged soil can lead to root rot and other diseases. Avoid planting in areas with poor drainage, such as low-lying spots or compacted soil. If your soil has drainage issues, consider incorporating organic matter, such as compost or well-rotted manure, to improve the soil structure and promote better drainage.

Preparing the Soil

Clearing the Area

Before you begin planting your Walla Walla onions, it is important to clear the designated area of any weeds, rocks, or other debris. Weeds can compete with your onions for nutrients and water, so it is crucial to remove them prior to planting. Use a garden rake or hoe to loosen the soil and remove any weeds or unwanted vegetation.

Adding Organic Matter

Adding organic matter to your soil is highly beneficial for the growth and development of Walla Walla onions. Organic matter, such as compost or well-rotted manure, enriches the soil with essential nutrients, improves its structure, and enhances its ability to retain moisture. Spread a layer of organic matter over the cleared area and incorporate it into the soil using a garden fork or tiller.

pH Testing and Adjusting

To ensure optimal growth, it is recommended to test the pH of your soil before planting your Walla Walla onions. A pH test kit can be purchased at your local garden center or online. Follow the instructions provided with the kit to obtain an accurate reading. If the pH level is outside the desired range of 5.8 to 6.8, you can adjust it by adding amendments, such as dolomite lime to raise the pH or sulfur to lower the pH. Follow the recommended dosage and guidelines on the product packaging for best results.

Planting Walla Walla Onions

Seed Selection

When it comes to planting Walla Walla onions, you have two options: starting seeds indoors or direct seeding. If you choose to start seeds indoors, select a variety of onion seeds specifically bred for Walla Walla onions. These seeds can be purchased from nurseries, seed catalogs, or online. Ensure that the seeds are fresh and from a reputable source to maximize germination rates and overall plant health.

Starting Seeds Indoors

To start Walla Walla onion seeds indoors, fill seed trays or pots with a well-draining seed-starting mix. Moisten the mix and sprinkle the seeds on the surface at a spacing of about 1 inch apart. Lightly cover the seeds with a thin layer of soil, and place the trays or pots in a warm location where they can receive ample sunlight or artificial grow lights. Keep the soil evenly moist and within a temperature range of 65 to 75°F (18 to 24°C) to promote germination.

Direct Seeding

If you prefer to skip the indoor seed starting process, Walla Walla onions can also be directly seeded into the garden. Wait until the soil has warmed up and there is no longer a risk of frost before sowing the seeds. Prepare the soil by loosening it with a garden fork or tiller, and create furrows approximately 1/4 to 1/2 inch deep. Sow the seeds thinly along the furrow, spacing them about 1 inch apart. Cover the seeds with soil and lightly firm the soil surface.

Spacing and Planting Depth

Determining the Spacing

Proper spacing is crucial for the healthy development of Walla Walla onions. The spacing requirements depend on whether you are growing them for green onions or mature bulbs. For green onions, you can plant them closer together, with a spacing of about 2 to 3 inches apart. If you want to grow larger bulbs, provide more room between the plants, spacing them approximately 4 to 6 inches apart. Additionally, leave about 12 to 18 inches of space between each row to allow for optimal air circulation and easy access for maintenance.

Planting Depth Considerations

When it comes to planting Walla Walla onions, the depth at which you plant the bulbs or seedlings is important. Planting too shallow can result in poor root development, while planting too deep can hinder emergence and growth. As a general guideline, plant the bulbs or seedlings so that the tip is just barely covered with soil. The roots should be able to reach downward easily and have room to expand within the soil.

Watering and Mulching

Watering Needs

Proper watering is essential for the growth and development of Walla Walla onions. Young transplants and newly seeded areas should be kept consistently moist but not waterlogged. As the plants mature, reduce the frequency of watering, allowing the soil to dry out slightly between waterings. Keep in mind that Walla Walla onions have shallow root systems, so watering deeply and infrequently is preferred over frequent shallow watering. Aim to water the plants at the base, avoiding overhead watering which can encourage diseases.

Mulching Benefits

Mulching around the base of your Walla Walla onions offers numerous benefits. Mulch helps to conserve moisture in the soil, reduce weed growth, and regulate soil temperature. Apply a layer of organic mulch, such as straw or shredded leaves, around the plants, being careful not to cover the bulbs or seedlings. Mulch also acts as a protective barrier, preventing soil splashing onto the leaves and reducing the risk of diseases.

Fertilizing the Onions

Choosing the Right Fertilizer

To ensure good growth and development, it is important to provide Walla Walla onions with the appropriate nutrients. When choosing a fertilizer, opt for a balanced organic fertilizer or a granulated slow-release fertilizer that is specifically formulated for onions or vegetables. These fertilizers typically have a ratio of nitrogen (N), phosphorus (P), and potassium (K) such as 10-10-10 or 14-14-14. Additionally, look for fertilizers that contain micronutrients such as calcium, magnesium, and boron.

Applying Fertilizer

Before planting your Walla Walla onions, incorporate a granular fertilizer into the soil according to the recommended dosage on the packaging. Work the fertilizer into the top few inches of soil using a garden fork or tiller. After planting, you can also apply a side dressing of fertilizer around the base of the plants when they are about 4 to 6 inches tall. Follow the recommended frequency and dosage instructions on the fertilizer packaging, and always water the plants after fertilizing to ensure proper nutrient absorption.

Controlling Weeds

Hand Weeding

Weeds can severely hinder the growth and productivity of Walla Walla onions. Regularly inspect your onion bed and remove any weeds promptly. Hand weeding is the safest method, as it allows you to carefully remove the weeds without damaging the onion plants. Use a handheld weeding tool or simply pull the weeds out by hand, being cautious not to disturb the surrounding soil or onion bulbs.

Mulching for Weed Suppression

Mulching is an effective strategy for suppressing weed growth in your Walla Walla onion bed. Apply a layer of organic mulch, such as straw or wood chips, around the plants, ensuring that the mulch does not touch the stems or bulbs. The mulch acts as a physical barrier, preventing weed seeds from germinating and competing with your onions for nutrients and water. Additionally, the mulch helps to maintain soil moisture and temperature, further benefiting the growth of your onion plants.

Pest and Disease Management

Common Onion Pests

Walla Walla onions can face attacks from various pests, such as onion maggots, thrips, and onion flies. These pests can cause damage to the foliage and bulbs, leading to reduced yields. To combat these pests, monitor your plants regularly for signs of infestation, such as wilting leaves, yellowing foliage, or insect activity. If detected early, you can manually remove the insects or use organic pest control methods, such as insecticidal soap or neem oil, to manage the infestation.

Preventive Measures

Preventing pest and disease problems is key to successful Walla Walla onion cultivation. Implementing good cultural practices, such as providing proper soil fertility, consistent watering, and appropriate spacing, can help promote healthy plant growth and reduce stress. Additionally, practicing crop rotation, avoiding excessive nitrogen fertilization, and removing plant debris after harvest can minimize the risk of pest and disease buildup in your garden. Regularly inspect your onion plants for any signs of disease or pest damage and take appropriate action when necessary.

Harvesting Walla Walla Onions

When to Harvest

Knowing when to harvest your Walla Walla onions is crucial to achieve the desired size and flavor. Generally, these onions are ready for harvest when the tops have toppled over and started to dry out. The foliage will turn yellow and brown, indicating that the bulbs have reached maturity. To test for readiness, gently dig around the bulb and check if it has reached the desired size and has a firm texture. Avoid leaving the bulbs in the ground for too long, as they can become overmature and prone to rot.

Harvesting Techniques

To harvest your Walla Walla onions, loosen the soil around the bulbs using a garden fork or shovel. Gently lift the bulbs from the ground, taking care not to damage the bulbs or stems. Once the onions are out of the ground, brush off any excess soil and remove the foliage, leaving only a few inches of the stem attached to the bulb. Allow the onions to cure and dry in a well-ventilated, shady area for about two to three weeks. During this time, the outer layers of the bulbs will dry and form a protective skin that allows for long-term storage.

Curing and Storing the Onions

Curing Process

Curing is an important step in preparing Walla Walla onions for long-term storage. After harvesting, place the onions in a single layer or hang them in bundles in a well-ventilated area with low humidity. Optimal curing conditions include a temperature range of around 75°F (24°C) and low levels of moisture. Allow the onions to cure for about two to three weeks until the outer layers are completely dried and the necks feel dry and papery. Proper curing helps to extend the shelf life of the onions and enhances their flavor.

Storage Conditions

Once the Walla Walla onions have been cured, they can be stored for several months under the right conditions. Choose a cool and dry storage area, such as a basement, pantry, or garage, with temperatures ranging from 35 to 40°F (2 to 4°C) and low humidity levels of around 65 to 70 percent. Avoid storing onions near potatoes or fruits that release ethylene gas, as this can cause onions to spoil more quickly. Place the cured onions in mesh bags or hang them in onion braids for proper air circulation and storage longevity.

In conclusion, successfully growing Walla Walla onions requires careful consideration of factors such as sunlight requirements, soil quality, and drainage. Preparing the soil through clearing, adding organic matter, and adjusting the pH level ensures a favorable growing environment. You can choose to start seeds indoors or direct seed, taking into account the spacing and planting depth considerations. Proper watering, mulching, fertilization, weed control, and pest management practices are essential throughout the growth stages of your Walla Walla onions. Knowing when to harvest and how to cure and store the onions properly ensures maximum flavor and storage longevity. With the right techniques and attention to detail, you can enjoy a bountiful harvest of delicious Walla Walla onions.