When winter temperatures plunge below freezing, many gardeners assume the growing season is over. However, with the right materials, smart design, and durable tarps, you can build a DIY winter greenhouse that protects your plants, even in sub-zero temperatures. This guide walks you step by step through building a cost-effective, highly insulated winter greenhouse using tarps, while maximizing heat retention and plant survival.
Whether you’re overwintering vegetables, herbs, or delicate ornamentals, this article will help you create a structure that rivals expensive commercial greenhouses at a fraction of the cost.
Why Build a DIY Winter Greenhouse with Tarps?
Traditional greenhouses made of glass or polycarbonate can be expensive and time-consuming to install. Tarps, on the other hand, offer:
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Affordable insulation
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Flexible sizing
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Easy installation and removal
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Excellent weather resistance
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High durability when using heavy-duty materials
High-quality tarps, especially polyethylene, clear vinyl, and insulated tarps, are designed to withstand harsh winter conditions, including snow loads, freezing rain, and strong winds.
Choosing the Right Location for Winter Success
Before construction, select a strategic location to maximize natural heat.
Best placement tips:
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Face the greenhouse south or southeast for maximum sunlight
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Use a wind-protected area, such as near a wall or fence
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Avoid low-lying spots where cold air settles
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Place it close to your home for easier monitoring
Sun exposure is your primary heat source in winter, so positioning is critical for maintaining above-freezing internal temperatures.
Best Tarps for a DIY Winter Greenhouse
Not all tarps are suitable for winter greenhouse use. Selecting the right type is the foundation of success.
1. Clear Poly Tarps (for Sunlight & Warmth)
Clear tarps allow maximum sunlight penetration, creating a greenhouse effect that traps heat during daylight hours.
Recommended use:
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Roof and sun-facing walls
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Daytime heat capture
Tarp Supply Inc.® clear poly tarps are UV-treated and cold-resistant, ensuring they remain flexible even in freezing conditions.
2. Heavy-Duty White or Silver Poly Tarps (for Insulation)
Opaque tarps reflect heat back into the structure and reduce nighttime heat loss.
Recommended use:
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North-facing walls
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Nighttime covers
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Wind-blocking layers
Tarp Supply Inc.®’s heavy-duty poly tarps are ideal for winter use due to reinforced hems and rust-resistant grommets.
3. Insulated or Vinyl Tarps (for Extreme Cold)
For sub-zero climates, adding an insulated layer is crucial.
Recommended use:
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Interior lining
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Removable nighttime insulation
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Base skirting
Vinyl tarps from Tarp Supply Inc.® offer superior durability, tear resistance, and temperature stability, making them perfect for long-term winter installations.
DIY Winter Greenhouse Frame Options
Your tarp is only as effective as the frame supporting it.
Popular DIY frame materials:
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PVC pipe (budget-friendly and lightweight)
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Metal conduit (stronger for snow loads)
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Wood frames (excellent insulation but heavier)
For snowy climates, reinforce the roof with a steep pitch to prevent snow buildup.
Step-by-Step: How to Build a Winter Greenhouse with Tarps
Step 1: Build the Frame
Construct a sturdy rectangular or hoop-style frame. Anchor it securely using ground stakes, concrete blocks, or buried posts.
Step 2: Install the Clear Tarp
Drape the clear tarp over the roof and south-facing side. Pull it tight to avoid sagging, and secure it using bungee cords or tarp clips.
Step 3: Add Insulating Tarps
Attach white, silver, or vinyl tarps to the remaining sides. Overlap seams to prevent drafts.
Step 4: Seal the Base
Use an extra tarp skirt along the bottom edges and weigh it down with bricks or sandbags to block cold air infiltration.
Step 5: Create a Door
Install a roll-up tarp door using grommets and rope for easy access while maintaining insulation.
How to Keep Plants Alive in Sub-Zero Temperatures
A tarp greenhouse alone helps, but combining it with smart heat-retention techniques ensures success.
Thermal Mass
Place black water barrels, buckets, or stones inside the greenhouse. These absorb heat during the day and release it at night.
Double-Layer Tarping
Create an air gap between two tarp layers. This trapped air acts as natural insulation, similar to double-pane windows.
Nighttime Covers
Cover plants with frost blankets or additional tarps during extreme cold snaps.
Supplemental Heat (Optional)
In harsh climates, consider:
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Solar greenhouse heaters
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Compost heat beds
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Low-wattage greenhouse heaters (with safety precautions)
Best Plants for Winter Greenhouses
Some plants thrive even in cold conditions when protected properly.
Cold-hardy favorites:
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Spinach
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Kale
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Swiss chard
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Lettuce
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Carrots
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Herbs like parsley and cilantro
With proper tarp insulation, many of these can survive temperatures well below freezing.
Common DIY Greenhouse Mistakes to Avoid
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Using thin, low-quality tarps that crack in cold weather
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Allowing snow to accumulate on flat roofs
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Leaving gaps at ground level
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Forgetting ventilation on sunny winter days (to prevent overheating)
Investing in commercial-grade tarps from Tarp Supply Inc.® helps eliminate many of these issues.
Why Choose Tarp Supply Inc.® for Your Winter Greenhouse?
When building a winter greenhouse, durability matters. Tarp Supply Inc.® offers:
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Heavy-duty poly tarps rated for extreme weather
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Clear tarps with superior UV protection
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Industrial-grade vinyl tarps for insulation
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Custom sizes to fit any DIY structure
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Reinforced hems and rust-resistant grommets
Their tarps are designed for real-world outdoor use, making them ideal for winter gardening projects.
Build Smarter This Winter
Don’t let freezing temperatures end your gardening season. With a DIY winter greenhouse built using high-quality tarps, you can protect your plants, extend your harvest, and save money.
Explore premium winter-ready tarps at Tarp Supply Inc.® today and get the durability, insulation, and performance you need to keep your plants alive, even in sub-zero temperatures.
Start building smarter. Start building stronger. Start with Tarp Supply Inc.®
