Frequently Asked Questions
Get expert answers to the most common questions about greenhouse gardening, setup, maintenance, and year-round growing techniques.
What size greenhouse do I need for my garden?
The ideal greenhouse size depends on your available space, budget, and growing goals. For hobby gardening, 6x8 feet is a popular starting size. Commercial operations typically start at 20x40 feet. Consider future expansion needs when planning.
What's the difference between polycarbonate and glass greenhouses?
Glass offers superior light transmission (90% vs 80%) and visual appeal, but costs more and is more fragile. Polycarbonate provides better insulation, is virtually unbreakable, and costs less, making it ideal for most applications.
How do I maintain proper temperature in my greenhouse?
Use automatic vent openers for ventilation, install shade cloth for summer cooling, and add heaters for winter warmth. Thermal mass like water barrels helps stabilize temperatures. Target 65-75°F during the day and 60-65°F at night.
What's the best foundation for a greenhouse?
Concrete foundations provide the most stability and longevity. Gravel foundations work well for smaller structures and cost less. Ensure proper drainage and level the foundation within 1/4 inch for optimal assembly.
Can I grow vegetables year-round in an unheated greenhouse?
Yes, with proper planning. Cold-hardy crops like kale, spinach, and lettuce can survive winter temperatures. Use row covers and thermal mass for additional protection. Season extension is possible in USDA zones 6 and above.
How much does it cost to operate a greenhouse annually?
Operating costs vary by size and climate. A 8x12 hobby greenhouse typically costs $200-500 annually for heating, with LED lighting adding $100-300. Larger commercial operations may cost $2-5 per square foot annually.
What permits do I need to build a greenhouse?
Requirements vary by location. Structures under 120 square feet often need no permits. Larger greenhouses may require building permits, electrical permits for wiring, and plumbing permits for water lines. Check local building codes.
How do I prevent pests and diseases in my greenhouse?
Practice good sanitation, quarantine new plants, ensure proper air circulation, and monitor humidity levels. Use beneficial insects for biological control. Maintain temperatures below 80°F and humidity below 70% to prevent most issues.
What's the best ventilation system for greenhouses?
Automatic vent systems work best, opening when temperatures rise and closing when they drop. Install roof vents and side louvers for optimal airflow. Plan for 15-20% of floor area in vent space for adequate ventilation.
Should I choose a lean-to or freestanding greenhouse?
Lean-to greenhouses cost less and share heat from your home but receive less light. Freestanding greenhouses offer more growing space and better light exposure but cost more. Choose based on your space and budget constraints.
How do I water plants efficiently in a greenhouse?
Drip irrigation systems provide the most efficient watering with minimal water waste. Water in the morning to reduce disease risk. Use mulch to retain moisture and consider automated timers for consistent watering schedules.
What crops are most profitable to grow in a greenhouse?
High-value crops include tomatoes, peppers, cucumbers, lettuce, herbs, and microgreens. Specialty items like exotic peppers or heirloom varieties command premium prices. Focus on crops that grow well in your climate zone.
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