Growing Onions in Missouri: Tips for a Bountiful Harvest

Welcome to this comprehensive guide on growing onions in Missouri. Whether you’re a seasoned gardener or a beginner, this article will provide you with all the tips and advice necessary to enjoy a successful onion harvest in Missouri.

In the following sections, we will cover everything from understanding the Missouri onion growing season to selecting the best onion varieties for Missouri, preparing the soil, planting techniques, essential care and maintenance, and troubleshooting common growing issues. We will also provide insights into the best practices for harvesting and storing onions in Missouri.

Missouri’s climate can be challenging for onion growth, but with the right knowledge and techniques, you can still enjoy a thriving onion crop. By the end of this article, you will be equipped with the information necessary to produce healthy, flavorful onions in your Missouri garden.

So let’s dive in and discover the secrets to growing onions in Missouri!

Understanding the Missouri Onion Growing Season

The ideal time to grow onions in Missouri is in the spring, typically between March and April. Onions require a long growing season, as they can take up to 100 days to mature, so it’s crucial to plant them as early as possible.

Before planting, it’s essential to prepare the soil by tilling it and amending it with organic matter such as compost. This will ensure that the soil is well-draining, fertile, and nutrient-rich.

Onions grow best in full sun, which is defined as at least six hours of direct sunlight per day. They also need consistent moisture, so it’s important to keep the soil evenly moist but not waterlogged.

Stages of the Growing Season

Stage Description
Planting Onion seeds or sets are planted in the spring.
Vegetative The onions develop green tops and establish their root systems.
Bulbing The onion bulbs start to form and grow in size.
Maturation The onion bulbs reach maturity and are ready for harvest.

During the bulbing stage, it’s important to reduce water to help the onions dry out and cure. This will allow them to develop a papery outer layer that will protect the bulb and keep it fresh for longer.

By understanding the Missouri onion growing season and following the tips and advice in this article, you can enjoy a bountiful onion harvest in your garden.

Choosing the Best Onion Varieties for Missouri

When it comes to selecting onion varieties for Missouri, it’s important to choose those that can thrive in the state’s climate and soil. Here are some onion varieties that are well-suited for Missouri’s growing conditions:

Onion Variety Preferred Growing Season Characteristics
Yellow Granex Fall and Winter Produces large, sweet onions that store well for up to 6 months. Best grown from sets instead of seeds in Missouri’s climate.
Red Wing Spring and Early Summer Produces medium-sized red onions that are sweet and mild. Resistant to disease and stores well for up to 5 months.
Walla Walla Spring Produces large, sweet onions that are best eaten fresh. Stores for up to 2 months. Best grown from transplants in Missouri’s climate.

When selecting onion varieties for your Missouri garden, consider the taste and cooking characteristics you prefer. For example, if you prefer sweeter onions for salads and raw dishes, yellow or white varieties may be best. If you typically cook with onions, red onions may provide a more robust flavor.

Additionally, make sure to choose onion varieties that are appropriate for the time of year you plan to plant. Some varieties, such as Yellow Granex, are best grown in Missouri’s fall and winter seasons, while others, such as Walla Walla, are best grown in the spring.

Preparing the Soil for Onion Planting in Missouri

Before planting onions in Missouri, it is important to prepare the soil adequately to provide optimal growing conditions. Below are steps to follow:

Step Description
Step 1 Test the soil to determine its pH level. The ideal pH range for onions is between 6.0 and 7.5.
Step 2 Add organic matter to the soil, such as compost or well-rotted manure, to help improve soil structure and drainage. Apply a 2-to-3-inch layer and mix it well into the soil.
Step 3 Add bone meal or superphosphate to the soil to provide necessary phosphorus for onion growth. Follow the recommended application rate on the package.
Step 4 Add a balanced fertilizer, such as 10-10-10 or 12-12-12, to the soil. Apply the fertilizer at a rate of 2 pounds per 100 square feet and mix it well into the soil.
Step 5 Rake the soil to create a smooth surface for planting.

By amending the soil properly, you can create an optimal growing environment for your onion plants.

Planting Onions in Missouri: Techniques and Best Practices

Planting onions in Missouri requires specific techniques to ensure optimal growth and development. Below are some best practices for planting onions in Missouri:

  • Start with quality onion sets: Choose firm and healthy onion sets that are specifically suited for Missouri’s climate. Sets that are too small or diseased are likely to result in poor growth or disease.
  • Prepare the soil: Onions thrive in well-draining soil with a pH range of 6.0-7.0. Prepare the soil by adding organic matter, such as compost or well-rotted manure, to improve soil structure and fertility.
  • Plant onions at the right time: In Missouri, onions are typically planted in mid to late March. Choose a sunny location and plant the onion sets approximately 1-2 inches deep and 4-6 inches apart.
  • Water onions regularly: Onions require consistent moisture to develop properly. Water them deeply at least once a week, or more frequently during dry spells. Avoid overwatering, as this can lead to disease and root rot.
  • Mulch the onion beds: Mulching helps to retain moisture in the soil, suppress weeds, and regulate soil temperature. Use a layer of organic mulch, such as straw or leaves, to cover the onion beds.
  • Fertilize onions: Onions require regular fertilization to sustain healthy growth. Apply a balanced fertilizer, such as 10-10-10, every 4-6 weeks throughout the growing season.

By following these planting techniques and best practices, you can ensure optimal growth and development of your onion plants in Missouri’s climate.

Essential Care and Maintenance for Missouri Onion Plants

Once your onions have been successfully planted in Missouri, it is important to care for them properly to ensure a healthy and bountiful harvest. Here are some essential care and maintenance tips to keep in mind:


Onions require consistent moisture throughout the growing season. Water your onion plants deeply once a week or more often if the soil is particularly dry. Avoid overwatering as onion plants may rot in a waterlogged soil.


Onions require adequate nutrients to thrive. Fertilize your onion plants with a balanced fertilizer every three weeks during the growing season. Alternatively, mix compost into the soil before planting to provide the necessary nutrients.


Mulching helps retain moisture in the soil and prevents weed growth around the onion plants. Apply a layer of organic mulch around the onion plants, ensuring that it does not touch the base of the plants. Avoid using plastic mulch, as it can trap heat and damage the onion plants.

Protecting from Pests and Diseases

Onions are susceptible to pests and diseases such as thrips, onion maggots, and Downy mildew. Monitor your onion plants regularly for signs of infestation and take appropriate action if necessary. Use insecticidal soap or Neem oil to treat pest infestations, and remove and dispose of infected plants to prevent the spread of disease.

By following these essential care and maintenance tips, you can ensure that your Missouri onion plants remain healthy and strong throughout the growing season.

Harvesting and Storing Onions in Missouri

Knowing when to harvest onions is essential to ensure that they reach full maturity and develop their characteristic flavor and aroma. In Missouri, onions are ready to harvest when their foliage turns yellow and starts to fall over. At this point, gently lift the onions from the soil and allow them to dry in the sun for a few days.

Once they are dry, remove any excess soil using a soft brush, taking care not to damage the delicate outer layers. Inspect each onion carefully for signs of damage, disease, or pest infestations, and discard any that appear compromised.

Storage Method Temperature Humidity Storage Duration
Room Temperature 60-70°F dry 2-3 months
Refrigeration 32-40°F dry 3-4 months
Freezing 0°F or lower dry up to 12 months

Onions can be stored in a variety of ways, depending on your preference and storage options. For short-term storage, they can be kept at room temperature in a dry, well-ventilated area for up to three months. Alternatively, onions can be stored in the refrigerator for up to four months, either whole or chopped. Freezing is also an option, with frozen onions maintaining their quality for up to 12 months.

Tip: Onions can be kept fresh longer if they are stored away from other fruits and vegetables, as they release gases that can cause nearby produce to spoil faster.

Troubleshooting Common Onion Growing Issues in Missouri

While growing onions in Missouri can be a rewarding experience, it’s not without its challenges. Here are some common issues you may encounter and tips for overcoming them:


Onion maggots and thrips are common pests that can affect onion growth in Missouri. To prevent infestations, use insecticidal soap or neem oil and keep the area around your onions free from debris. You can also plant onions earlier in the season to avoid the peak of pest activity.


Fungal diseases such as onion rust and downy mildew can be a problem in Missouri’s humid climate. To prevent these diseases, avoid overhead watering and ensure proper plant spacing for air circulation. Additionally, use fungicide treatments as a preventative measure.

Environmental Factors

Moisture stress can impact onion growth in Missouri during periods of drought or excessive rainfall. To combat this issue, use mulch to retain moisture and provide consistent watering. Additionally, be sure to plant onions in well-draining soil to prevent waterlogged roots.

By being proactive and addressing any issues promptly, you can help ensure a successful onion harvest in Missouri. Happy growing!


By following the tips and advice detailed in this article, you can grow robust and healthy onions in Missouri’s climate. Remember to choose the right onion varieties, prepare the soil adequately, and provide proper care and maintenance to your plants throughout the growing season.

By doing so, you’ll be able to enjoy a bountiful onion harvest in your Missouri garden. Don’t be discouraged by any setbacks you encounter along the way, as many common issues can be addressed with the right knowledge and tips.

So get started on your onion-growing journey today and enjoy the satisfaction of growing your own delicious and healthy onions right at home. Happy gardening!


Q: When is the best time to plant onions in Missouri?

A: The ideal time to plant onions in Missouri is typically in early spring, around March or April. This allows the onions to establish their roots before the heat of the summer.

Q: What are the best onion varieties for Missouri?

A: Some recommended onion varieties for Missouri include ‘Yellow Sweet Spanish’, ‘Texas Grano’, and ‘Walla Walla’. These varieties have proven to thrive in Missouri’s climate.

Q: How do I prepare the soil for planting onions in Missouri?

A: It’s crucial to prepare the soil adequately before planting onions in Missouri. Start by testing the soil’s pH level and make any necessary adjustments. Amend the soil with organic matter, such as compost or well-rotted manure, to improve its fertility and drainage.

Q: What are the best practices for planting onions in Missouri?

A: When planting onions in Missouri, ensure proper spacing of about 4-6 inches between each onion bulb. Plant them at a depth of 1-2 inches, with the pointed end facing upward. Water the newly planted onions thoroughly and mulch around the plants to conserve moisture and control weeds.

Q: How do I care for and maintain my onion plants in Missouri?

A: To care for onion plants in Missouri, water them consistently, keeping the soil evenly moist but not waterlogged. Fertilize the plants with a balanced fertilizer every few weeks. Monitor for common pests like onion maggots and diseases like downy mildew, and take appropriate measures to protect your plants.

Q: When and how should I harvest and store onions in Missouri?

A: Onions are ready for harvest in Missouri when the tops start to dry and fall over. Carefully lift the bulbs from the ground and let them cure in a warm, dry, and well-ventilated area for a couple of weeks. Once cured, store the onions in a cool and dry place with good airflow to prolong their shelf life.

Q: What should I do if I encounter issues with onion growing in Missouri?

A: If you encounter problems with onion growing in Missouri, such as pests, diseases, or environmental factors, identify the issue and take appropriate action. Use organic pest control methods, treat diseases promptly, and adjust growing conditions to mitigate any adverse effects.