Greenhouse FAQs: Real Answers from a Couple Who've Made All the Mistakes So You Don't Have To

 After helping our third neighbor assemble their greenhouse (and finally figuring out where that mysterious extra bolt goes), my wife and I have fielded enough questions to write a book. Instead, here's a FAQ that addresses the most common head-scratchers we've encountered.

 

Is it cheaper to build or buy a greenhouse?

Having crunched the numbers both ways (and accidentally bought enough extra materials to build a small shed), here's the truth: Building from scratch can save you about 30-40% IF you:

• Already own the right tools
• Have decent DIY skills
• Value your time at $0/hour
• Don't mind multiple hardware store runs

👉 Otherwise, a kit is your friend. Trust me, your marriage will thank you.

 

What are the 5 disadvantages of a greenhouse?

Let me be real with you:

• Temperature management becomes your new hobby (my wife now has more weather apps than social media)
• Constant monitoring required (yes, even during the Super Bowl)
• Higher water bills (those plants are thirstier than teenagers after soccer practice)
• Initial setup costs can be steep (especially if you get "upgrade fever" like we did)
• Pests can throw parties in there (turns out aphids love an enclosed space as much as your plants do)

What not to grow in a greenhouse?

After some "learning experiences," we've found these are best kept outside:

• Super tall crops like corn (unless you enjoy ducking)
• Sprawling squash and pumpkins (they're like teenagers - they need more space than you think)
• Plants that need pollinator access (unless you enjoy playing bee with a paintbrush)
• Crops that hate high humidity (garlic and onions prefer the great outdoors)

 

How big of a greenhouse do I need to be self-sufficient?

The golden rule we've discovered: 100 square feet per person for year-round veggies. But here's the catch - this assumes:

• You're an organized planting ninja
• You utilize vertical space like a Manhattan architect
• You're okay eating seasonally
• You don't mind some creative crop rotation

My wife and I found that a 8'x12' greenhouse keeps us in year-round greens and seasonal veggies for two people, plus some to share with neighbors (which helps when you need their help moving heavy things).

How do I keep my greenhouse warm in the winter?

After one winter of playing "plant rescue," here's our tried-and-true strategy:

• Thermal mass is your BFF (we use black water jugs - cheap and effective)
• Double-layer bubble wrap on walls (like a cozy jacket for your greenhouse)
• Proper sealing (draft-hunting becomes a winter sport)
• Heavy row covers at night (think plant blankets)
• A small electric heater for emergencies (our "panic button" solution)

👉 Those cheap solar pool rings? Amazing heat collectors during winter days.

Are greenhouse kits worth it?

Short answer: Yes. Long answer: Yeeeeeees. Here's why:

• Pre-drilled holes actually line up (mostly)
• Instructions exist (though sometimes in questionable English)
• Warranty coverage (when things go sideways)
• Proven designs (someone else already made the mistakes)
• Resale value (try selling a DIY greenhouse on Facebook Marketplace...)

Should a greenhouse be in sun or shade?

Think of your greenhouse like a solar-powered plant spa - it needs maximum sun exposure. But there are nuances:

• East-West orientation is ideal
• Morning sun is better than afternoon sun
• A bit of afternoon shade in hot climates isn't bad
• Avoid tree shade (unless you enjoy cleaning gutters)

My wife's motto: "If it's not getting 6+ hours of direct sun, it's just an expensive storage shed."

Do you need bugs in a greenhouse?

Ah, the great bug debate! 

You need:

• Pollinators (hand pollination gets old fast)
• Beneficial insects (ladybugs are your tiny warriors)
• Decomposers in the soil (worms are your underground crew)

But you don't need:

• Aphids (they'll find their way in anyway)
• Spider mites (the bane of every greenhouse owner)
• That weird beetle thing you can't identify (just no)

What is the lowest temperature plants can survive in a greenhouse?

Without supplemental heat:

• Uninsulated greenhouse: 20°F warmer than outside
• Insulated greenhouse: 30°F warmer than outside
• With cold-hardy plants: Some survive to 28°F
• Tender plants: Need 55°F minimum

👉 My wife's rule: If you're wearing a winter coat in there, your plants aren't happy.

Should a greenhouse have a floor?

Based on our experience (and one muddy disaster):

• Gravel base: Excellent drainage, good pest control
• Pavers: Great for walkways
• Bare earth: Fine for permanent beds
• Concrete: Overkill for most home greenhouses

We use gravel paths with soil beds - best of both worlds.

Do I need electricity in my greenhouse?

Need? No. Want? Absolutely. Here's why:

• Fans for ventilation (hot air rises, but it needs encouragement)
• Heating in winter (sometimes Mother Nature needs help)
• Grow lights for seedlings (because winter days are short)
• Electric propagation mats (happy roots = happy plants)
• Power for your "greenhouse office" (my wife's term for her potting bench)

How to prevent spider mites in a greenhouse?

After the Great Spider Mite Battle of 2024, here's our prevention strategy:

1. Maintain humidity above 60% (they hate wet parties)
2. Regular neem oil treatments (prevention beats cure)
3. Beneficial insects (unleash the predatory mites!)
4. Good air circulation (fans are your friends)
5. Inspect new plants (quarantine isn't just for humans)

👀 If you see webs, you're already in trouble. Act fast and pray.

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About the Author

Meet Mike! By day, he's a seasoned office warrior juggling multiple roles. When he’s not at his desk, Mike’s exploring the lighter side of life with a dash of humor. From researching the latest trends to diving into hobbies like outdoor activities, he’s always up for new adventures. As a dedicated family man, Mike loves spending quality time with his wife and teenage kids, sharing their joys and passions. Alongside his varied pursuits, Mike enjoys contributing insights to multiple blogs, sharing his experiences and discoveries with a wide audience.