What to Plant in a Texas Greenhouse for Fall Vegetables

Growing fall vegetables in a Texas greenhouse gives you control over temperature, humidity, pests, and season length so you can harvest higher quality crops later into the year than outdoor beds allow. This guide explains what to plant, when to plant it, and how to manage environmental conditions for success across Texas regions. It focuses on practical, region-aware recommendations, soil and irrigation methods, pest and disease prevention, and step-by-step planting and succession plans you can apply in most hobby or small-market greenhouses.

Why a greenhouse for fall in Texas?

A greenhouse extends or shifts the growing season by reducing heat stress in late summer and providing frost protection in late fall. In Texas, summers can linger and early frosts can surprise you; a greenhouse lets you:

• Protect cool-season crops from late-summer heat spikes that cause bolting.
• Start seeds and raise transplants earlier than outdoors.
• Grow cool-season crops well into winter in the milder Gulf and South Texas regions.
• Reduce insect pressure through exclusion and better sanitation.

Choosing the right crops and managing heat, humidity, and light are the keys to reliable fall harvests.

Texas regional timing and planning

Texas is large and diverse. Rather than fixed calendar dates, use your average first frost date as the anchor.

• Panhandle and High Plains: first frost often in October. Start planning seedlings in July and sow most cool-season crops from late August through early September.
• North Texas and Red River Valley: first frost commonly late October to mid November. Sow from mid August through October depending on crop.
• Central Texas (Austin corridor): first frost often late November. Start transplants in September and direct-sow from September through November.
• Gulf Coast: milder, first frost generally December to January. You can plant well into October and even November for many greens.
• South Texas: frost is rare; you can often plant greens from September through December and overwinter many crops.

General rule of thumb:

• Sow brassica transplants 6 to 10 weeks before first frost.
• Direct-sow quick crops (radish, lettuce, spinach) 2 to 6 weeks before first frost for staggered harvests.
• Plant garlic and overwintering onions in the fall (8 to 12 weeks before coldest period in your area) for spring harvest.

Best fall vegetables for Texas greenhouses

Choose crops that prefer cool to moderate temperatures and tolerate short nights. The following list highlights top performers, why they work, and any special greenhouse considerations.

Leafy greens and salad crops

• Lettuce (leaf and romaine): fast-growing, prefers daytime 60-70 F and nights 45-55 F. Use shade cloth during any remaining hot spells. Harvest as baby leaf or mature heads. Sow every 2 weeks for continuous harvest.
• Spinach: cold-hardy and flavorful; direct-sow or transplant. Avoid high heat that causes bolting.
• Arugula, mizuna, tatsoi, and other Asian greens: very fast and heat-sensitive; sow in succession for a steady supply.
• Swiss chard: more heat tolerant than other greens; good bridge crop through early winter in milder zones.

Brassicas (cole crops)

• Broccoli, cauliflower, cabbage, collards, kale: excellent fall/winter crops. Transplant seedlings 6-10 weeks before first frost to allow head formation in cool weather. Watch for caterpillars and aphids; use insect-exclusion mesh or biological controls.
• Brussels sprouts: long season crop. Start early and expect harvest into winter in milder regions.

Root crops and bulbs

• Carrots: direct-sow seed; cooler soil improves flavor. Thin carefully.
• Beets: direct-sow or transplant; harvest greens young or leave roots to mature.
• Radishes and turnips: very quick; perfect for succession crops between slower sowings.
• Garlic: plant in fall for late spring/summer harvest; choose varieties appropriate to your daylength region.
• Onions: sets or transplants in fall for overwintering; use short-day or long-day varieties based on your latitude.

Legumes and vining crops

• Peas (snap, snow, shelling): sow early in the fall for best yields; they prefer cool days and chilly nights. Trellis inside the greenhouse.
• Bush beans are less reliable in fall heat; use only in cooler regions or late fall.

Herbs and specialty greens

• Cilantro, parsley, dill: best in fall to avoid bolting in heat.
• Basil will decline as temperatures cool; keep for early fall but expect reduced vigor later.
• Microgreens and baby lettuces: excellent quick-turn crops for continuous income or household use.

Greenhouse environment control for fall

Greenhouses in Texas must manage both cooling from lingering summer heat and warming to prevent frost damage.

Temperature management

• Ventilation and shading: Install adjustable roof and side vents and use 30-50% shade cloth when ambient temps exceed 85 F to prevent bolting.
• Night heating: For colder snaps, simple electric or propane heaters with a thermostat can hold night temps above 40 F for sensitive transplants. Many cool-season crops tolerate down to mid 20s F if briefly exposed, but repeated freezes will damage young transplants.
• Thermal mass: Add water barrels or stone to moderate night-time temperature swings.

Humidity and air movement

• Keep humidity moderate to reduce fungal disease. Use circulating fans to move air and dry leaf surfaces.
• Avoid overhead watering late in the day. Water early morning so leaves dry quickly.

Light

• Daylight hours shorten in fall. Most cool-season crops do fine without supplemental light if light levels are reasonable; however, seedlings started indoors often benefit from grow lights to avoid legginess.

Soil, containers, and water management

• Use well-draining soilless mix or an amended greenhouse soil with plenty of compost. Aim for pH 6.0 to 6.8 for most vegetables.
• Fertility: sidedress or apply balanced organic fertilizer at planting and every 3-4 weeks for heavy feeders like brassicas.
• Irrigation: drip irrigation or micro-sprays deliver consistent moisture and keep foliage dry. Use timers to maintain regular schedules; young seedlings need frequent but shallow waterings, mature roots need deeper, less frequent water.
• Monitor EC (electrical conductivity) if using soilless media and fertigation. Maintain mild to moderate nutrient solution strength for leafy crops and slightly higher for fruiting crops.

Pest and disease management in the greenhouse

Greenhouses reduce some pests but can concentrate others.

• Inspect plants weekly for aphids, thrips, whiteflies, fungus gnats, and caterpillars.
• Use sticky traps, insect-exclusion screens, and beneficial insects (lady beetles, parasitic wasps) where permissible.
• Sanitation: remove old crop debris, sterilize pots and tools, and quarantine new plants before introducing them.
• Manage fungal disease by controlling humidity, spacing plants for airflow, and removing infected tissue promptly. Use organic fungicides only as needed and according to label directions.

Planting and succession strategy

• Succession sowing is the backbone of a productive fall greenhouse. Stagger sowing every 10-14 days for salad greens, every 3-4 weeks for slow crops.
• Interplant fast crops (radishes, baby greens) between slower brassica transplants to maximize space.
• Use staging benches: early seedlings near the front, maturing plants further back.
• Transplanting: harden off seedlings for several days by reducing water and exposing to cooler nights before planting into the greenhouse beds.

Sample planting schedule (by crop type and weeks before first frost)

• Brassicas (transplants): plant 6 to 10 weeks before first frost.
• Leafy greens (direct-sow): sow 2 to 6 weeks before frost; continue sowing every 2 weeks.
• Root crops: direct-sow 4 to 8 weeks before frost for best flavor; carrots and beets can be sown later for baby roots.
• Peas: sow 6 to 8 weeks before first frost.
• Garlic and overwintering onions: plant 8 to 12 weeks before your coldest winter period.

Adjust based on your local frost date and the greenhouse microclimate.

Practical checklist for fall greenhouse success

• Ventilation: inspect and test vents, fans, and shade cloth before fall heat lingers.
• Sanitation: clear out summer crop debris and sanitize benches and pots.
• Soil prep: topdress with compost, check pH, and refresh potting mixes.
• Seed inventory: choose varieties labeled for fall, cold-tolerant, or short-season performance.
• Tools and supplies: stock row cover, frost cloth, auxiliary heating, sticky traps, and basic organic pest controls.
• Irrigation: repair or install drip lines and set timers for consistent moisture.

Final takeaways

Plant fall vegetables in a Texas greenhouse by working backward from your average first frost. Prioritize cool-season greens, brassicas, root crops, and legumes that respond well to cooler temperatures and shorter days. Control heat and humidity with vents, shade cloth, and good air circulation. Use succession sowing and intercropping to keep a steady harvest, and maintain sanitation and monitoring to prevent insect and disease buildups. With a few simple adjustments and sensible crop choices, a Texas greenhouse will reward you with high-quality fall and winter produce that outperforms outdoor beds.