Onion in Zone 6B — Texas

Growing onions in Zone 6B Texas gives you access to sweet, flavorful bulbs that store beautifully through our mild winters. Unlike store-bought onions that travel thousands of miles, your homegrown varieties develop complex flavors suited to our climate and soil. With our long 230-day growing season, you can grow substantial bulbs that rival anything from the grocery store, plus you'll have fresh green onions throughout the growing period.

The Texas heat and unpredictable weather can challenge onion growing, but timing makes all the difference. Plant early to take advantage of cool spring weather for bulb development, then let them cure during our hot summers. Our extended growing season gives you flexibility that gardeners in shorter zones don't have, allowing you to experiment with both spring and summer plantings.

Starting onion seeds indoors works well in Texas if you want the largest possible bulbs and access to specialty varieties. Sow seeds in late December through mid-January, about 10 weeks before your transplant window. Use seed trays with good drainage and bottom watering to prevent damping-off disease in our variable humidity.

Keep seeds at 65-70°F for germination, then provide bright light once they sprout. A sunny south window works, but grow lights give more consistent results during our often-cloudy winter days. Onion seedlings grow slowly at first, looking like thin grass blades for weeks.

The main advantage of starting from seed is variety selection and bulb size. Transplants started this early develop into the largest bulbs by summer. However, onion sets are much easier for beginners and still produce excellent results in our Texas climate.

Transplant onion seedlings outdoors from mid-March through early April, after hardening them off gradually over a week. Start with just an hour outdoors, increasing daily until they're acclimated to direct sun and wind. Our early spring weather can swing from mild to surprisingly chilly, so watch the forecast.

Space transplants 4-6 inches apart in rows or wide beds. Plant them at the same depth they were growing in containers - onions form bulbs at soil level, so proper depth matters. The crown should sit right at the soil surface, not buried deep like other transplants.

Choose a sunny spot with loose, well-draining soil. Onions hate wet feet, which can be challenging during our unpredictable spring rains. If you have heavy clay, consider raised beds or work in compost to improve drainage before planting.

Direct sowing onion seeds works in Texas but requires patience and consistent moisture. Sow seeds from late February through mid-July, though spring plantings generally perform better than summer ones. Seeds germinate slowly in cool soil, taking 2-3 weeks to emerge.

Prepare your soil by working in compost and ensuring good drainage. Onion seeds are tiny, so plant them just ¼ inch deep and keep the soil consistently moist until germination. Thin seedlings to 4-6 inches apart once they're established - you can eat the thinnings as green onions.

Most Texas gardeners find onion sets (small bulbs) easier and more reliable than direct seeding. Sets transplant without shock, establish faster, and give you a head start on bulb formation. Save direct seeding for specialty varieties you can't find as sets.

Onions need consistent moisture during their early growing season but require careful water management as they mature. In Texas, this means regular watering through spring and early summer, then backing off as tops begin to yellow. Water deeply when the top 2 inches of soil feel dry to your finger.

During our hot Texas summers with typical highs around 97°F, onions may need water twice weekly if rainfall doesn't cooperate. Apply about 1 inch per week through drip irrigation or soaker hoses rather than overhead sprinklers. Watering at the base prevents splash-back diseases and works better in our variable humidity.

Stop watering completely once onion tops start falling over and yellowing - this signals bulb maturity and the beginning of natural curing. Continued watering at this stage prevents proper curing and reduces storage life. The timing usually coincides with our hottest summer weather, when you're glad to have one less thing to water.

Apply 2-3 inches of mulch around plants to conserve moisture and moderate soil temperature during our extreme heat. Grass clippings or shredded leaves work well, but keep mulch away from the bulb necks to prevent rot during our humid spells.

Expect your first onion harvest from early June through mid-November, depending on when you planted and which varieties you chose. The key harvest indicator is when tops begin falling over and yellowing naturally - this usually happens about 100 days from transplanting. Don't pull them too early or the bulbs won't store properly.

Harvest on a dry day if possible, gently lifting bulbs with a fork rather than pulling by the tops. Brush off soil but don't wash them - onions need to cure with their papery outer layers intact. If rain threatens, harvest anyway and move them to a covered area immediately.

Cure freshly harvested onions in a warm, dry, well-ventilated area for 2-3 weeks before storing. Our hot Texas summers provide ideal curing conditions - spread them on screens in a garage or covered porch where air circulates freely. Properly cured onions will have papery outer skins and dried-down necks.

As our first frost approaches in early November, harvest any remaining onions whether they're fully mature or not. Green onions and partially formed bulbs are still usable fresh, even if they won't store long-term.

Onion Thrips These tiny, pale insects feed on onion leaves, creating silvery streaks and stippling. Heavily infested plants look bleached and may have black specks (thrips excrement) on the foliage. Thrips thrive in our hot, dry Texas weather and can quickly build up populations during summer heat.

Hot, dry conditions favor thrips development, and they're particularly problematic during drought periods. Regular overhead watering helps reduce populations, and row covers work during early growth stages. Blue sticky traps can help monitor and catch adults.

Pink Root This fungal disease causes onion roots to turn pink, then purple, then black as they rot away. Affected plants grow slowly, yellow prematurely, and produce small bulbs. The disease persists in Texas soil and worsens during hot, humid periods followed by dry spells.

Pink root spreads through infected soil and plant debris, thriving in our unpredictable weather patterns. Improve soil drainage and avoid planting onions in the same area for 3-4 years. Choose resistant varieties when possible, and ensure good air circulation between plants.

Bolting Onion plants send up flower stalks prematurely, usually triggered by temperature stress or long day length. Once bolted, the bulb becomes woody and the neck thick and tough. This commonly happens during our late spring heat waves or if plants experience cold snaps after warm weather.

Plant at the right time for Texas conditions and choose varieties suited to our climate. Provide afternoon shade during extreme heat spells and keep soil consistently moist. Remove flower stalks immediately if they appear, though the bulb quality may already be compromised.

Texas Specific Challenges: Our extreme heat and unpredictable rainfall create perfect conditions for many onion problems. The combination of intense sun, variable humidity, and sudden temperature swings stresses plants and makes them more susceptible to pests and diseases. Fire ants may also disturb newly planted sets, requiring vigilance during establishment.

Onions make excellent companions for carrots, beets, lettuce, and tomatoes in Texas gardens. Plant them alongside carrots - the onions repel carrot flies while carrots help break up soil for onion root development. Lettuce appreciates the light shade from onion foliage during our intense spring sun, and both crops harvest at different times so they don't compete.

Tomatoes and onions work particularly well together in our two-season growing pattern. Plant onions in early spring, harvest them by midsummer, then plant fall tomatoes in the same space. Avoid planting onions near beans or peas - they can inhibit the nitrogen-fixing bacteria that legumes depend on, and beans may actually stunt onion growth through root competition.