Practical Tips for Growing Broccoli in High Tunnels

Growing broccoli in high tunnels offers an excellent way to extend the growing season and protect your crops from harsh weather conditions. With proper planning and management, you can achieve a healthy and productive broccoli harvest. Here are some practical tips to help you succeed.

Choosing the Right Variety

Select broccoli varieties suited for high tunnel cultivation. Look for cultivars that mature early and are resistant to common pests and diseases. Some popular options include ‘Calabrese’, ‘Packman’, and ‘Diplomat’.

Preparing the High Tunnel

Ensure your high tunnel is well-ventilated and has a reliable heating system if you plan to grow during colder months. Prepare the soil by adding organic matter and testing pH levels, aiming for a pH of 6.0 to 7.0. Incorporate compost or well-rotted manure to enrich the soil.

Soil Preparation

Loosen the soil to a depth of at least 12 inches. Remove weeds and debris. Use a soil test kit to determine nutrient levels and amend accordingly. Incorporate slow-release fertilizers if necessary.

Planting Broccoli

Start seeds indoors 4-6 weeks before the last expected frost date. Transplant seedlings into the high tunnel when they are 4-6 inches tall, ensuring proper spacing of 18-24 inches between plants. Harden off seedlings before transplanting to reduce transplant shock.

Timing

Plan your planting schedule based on your local climate and the tunnel’s conditions. For fall harvests, plant in late summer. For spring crops, transplant in early spring.

Growing and Maintenance

Maintain consistent moisture levels, watering deeply once a week. Mulch around plants to conserve soil moisture and suppress weeds. Use row covers or insect netting to protect against pests such as aphids and cabbage worms.

Temperature Management

Broccoli prefers daytime temperatures of 65-75°F. Use fans or heaters to regulate temperature during colder months. Ventilate the tunnel on warm days to prevent overheating.

Fertilization

Apply a balanced fertilizer at planting time. Side-dress with nitrogen-rich fertilizer when plants are about half-grown to promote healthy head development. Avoid excessive nitrogen, which can lead to lush foliage but poor head formation.

Pest and Disease Control

Monitor plants regularly for pests such as aphids, cabbage worms, and flea beetles. Use organic insecticides or introduce beneficial insects like ladybugs. Practice crop rotation and remove plant debris to reduce disease risk.

Common Diseases

• Downy mildew
• Black rot
• Alternaria leaf spot

Implement proper sanitation and avoid overhead watering to minimize disease occurrence. Use resistant varieties when available.

Harvesting

Harvest broccoli when the heads are firm, tight, and uniform in color. Typically, this occurs 70-100 days after transplanting. Cut the head with a sharp knife, leaving several inches of stem. Side shoots may develop after the main head is harvested, providing additional harvests.

Conclusion

Growing broccoli in high tunnels can be highly productive and extend your growing season. With careful variety selection, proper soil preparation, consistent maintenance, and pest management, you can enjoy fresh, homegrown broccoli year-round. Happy gardening!