I. Introduction

If you've been curious about starting your very own onion patch, here's an authoritative guide of how to plant onions in Texas. From soil preparation to the first delicious bulb harvested in your own backyard.

II. Understanding Onion Varieties

1. Short-Day Varieties

These onions thrive in the mild winters and short days of South Texas. Good selections include Texas Grano 1015Y, Red Creole and Texas Early White. You can plant them from sets due to their limited shelf life.

2. Intermediate-Day Varieties

Slightly more versatile, these onions are well-suited to Central Texas' intensifying heat. Consider Red Candy and Yellow Granex. They store longer than their short-day counterparts. Click here for more information.

3. Long-Day Varieties

In the cooler, more northern parts of the state, long-day onions enjoy the extended daylight hours. Rio Bravo and Yellow Stuttgarter are excellent choices. Their high sulfur content means they're better for cooking than eating raw.

III. Preparing the Soil

1. pH adjustment

A successful onion harvest begins with the soil. Onions often prefer a light, sandy loam with a slightly acidic pH between 6.0 and 6.8. Texas soils typically do well in providing this. But it's always good to check and amend, if necessary.

Start by conducting a soil test with your local agricultural extension service. Once you have your results, it's time to adjust the pH. Sulfur can help lower it if the soil is too basic. Lime can raise it if it is too acidic. Work this into the top six inches of your garden bed.

2. Soil Amendment

Start by ensuring you have a sunny spot. Onions despise soggy feet. Ensure your onions square foot garden has adequate drainage. Consider adding organic matter to improve it. For example, peat moss or compost. Especially if you have heavier clay soils. Sandy soils may require richer amendments to increase water retention.

IV. When to Plant Onions in Texas?

For those looking to overwinter onions, you should plant short-day varieties from October 1 to November 15. The cooler temperatures of early winter initiate bulb formation, and the onions will resume growth and mature in spring.

If you prefer planting in spring, the best time to plant onions in Texas is January to February. You should use intermediate or long-day varieties. These onions will grow slowly through the cooler spring. The bulb will be triggered by longer daylight hours in May and June.

1. When to Plant Onions in North Texas?

Growing onions in north Texas from late January to early February is best. Because you should plant onions 4–6 weeks before the last spring freeze.

2. When to Plant Onions in Central Texas?

Planting onions in central Texas from October to February is ideal. Onion plants are sensitive to both day length and temperature. So timing is critical.

3. When to Plant Onions in South Texas?

In south Texas, you can plant onion seeds in the fall. From late September to mid-November and over winter.

V. How to Grow Onions in Texas?

1. Seed Sowing Guidelines

You should plant onions 1 inch deep. Make sure to plant them 4 inches apart in rows and 12-18 inches apart. Water your onions regularly. But do not overwater as this can lead to rot.

2. Transplanting Seedlings

Seedlings should be around pencil-thick when they're ready for transplant. This is typically six to eight weeks after starting from seeds. Harden them off first before growing onions in Texas. Acclimating the plants to the outdoor environment gradually. Planting sprouted onions is also available.

VI. Watering and Maintenance

1. Watering Requirements

Consistent watering regimen to develop strong roots and larger sweet onions bulbs. Inconsistent moisture will lead to unsightly and underdeveloped bulbs. Water them deeply once a week, more or less depending on your rainfall. Aiming to provide up to an inch of water.

2. Mulching techniques

Maintaining weed-free beds is crucial. Onions don't take kindly to competition. A layer of mulch is an onion’s best friend, keeping moisture in and weeds down. Organic mulch can help retain moisture and breaks down over time, enriching the soil. For example, straw or wood chips.

3. Fertilization schedule

Fertilize every few weeks with a balanced fertilizer that includes nitrogen, phosphorus, and potassium (like a 10-10-10). Keeping the dose in check. Too much nitrogen will result in beautiful green tops but pitifully small bulbs.

Follow the instructions on the package. You can also add a teaspoon of fertilizer per onion. Ensure you distribute it evenly and water it in well.

VII. Pest and Disease Management

1. Common Pests

Thrips and onion maggots are a real nuisance to your alliums. These tiny pests can stunt growth or lead to bulbs that fail to store properly. Be vigilant with your inspection, working to mitigate their influence as early as possible.

2. Organic and Chemical Control Methods

For onions square foot gardening, interplanting onions with strong-smelling herbs can deter pests. For example, sage, thyme, or rosemary. Physical barriers like row covers can shield young onions from maggots. Practicing crop rotation will help avoid a persistent thrip population.

When natural methods aren't sufficient, turn to insecticidal soaps or other registered products to control outbreaks. It's vital to always read and follow the label instructions.

3. Common Diseases

Disease management is equally important. Fungi like white rot, pink root, and downy mildew can affect green onions in Texas. Rotate your crops, manage moisture levels, and practice proper spacing to prevent these diseases from taking hold. Additionally, selecting disease-resistant varieties can help mitigate these issues. 

VIII. Harvesting and Storage

1. Signs of Readiness

The harvested onions' readiness is indicated by the yellowing and toppling of their leaves. An additional clue that they're ready to harvest is when the necks (the stem that extends from the bulb's top) start to feel soft or bend.

2. Harvesting Techniques

To harvest, gently loosen the soil around the bulb with a garden fork or trowel. Pull the bulbs out by hand, brush off any excess soil. Lay the onions out in a single layer to cure. Cure onions in a warm, dry area for a couple of weeks. This can toughen up their skin for storage.

3. Storage Tips

After curing, cut off the roots and trim the tops. Leave about an inch of the neck intact. Store your onions in a cool, dry, and well-ventilated place.

A basement or garage works well. Ensure they are away from light. Store them in a single layer to avoid mold. Mesh or paper bags provide the perfect level of air circulation necessary to prevent spoilage.

IX. Troubleshooting Common Issues

1. Addressing Bolting and Yellowing Leaves

Onions bolt, or prematurely produce a flower stalk, when stressed. This is often due to temperature fluctuations or water issues. To avoid this, choose the right varieties and plant at the correct time. Provide consistent moisture and avoid planting them too closely together.

2. Preventing Bulb Rot and Other Diseases

Bulb rot is often caused by fungal infections due to excessive moisture. Ensure proper spacing between plants and good air circulation. If you notice any signs of rot, promptly remove and dispose of affected bulbs to prevent the spread.

X. Conclusion

Consult with local agricultural extensions when in doubt. Determine the best fits for growing onions in Texas.