Convert a Shed into a Backyard Greenhouse
Backyard Shed → Backyard Greenhouse
Transform a standard backyard shed into a year-round greenhouse by replacing wall and roof sections with polycarbonate panels, adding ventilation, building raised growing beds, and installing an irrigation system for growing vegetables, herbs, flowers, and seedlings.
Cost Range
$1,500 – $8,000
Timeline
2–5 weeks
Materials Cost
$2,395
Permits Cost
$150
Steps
Assess the Shed and Plan Light Exposure
Evaluate your shed for structural integrity — the frame needs to support polycarbonate panels and withstand wind and snow loads. Determine which walls receive the most sunlight (south-facing is ideal in the Northern Hemisphere). Plan to replace the south-facing wall and at least part of the roof with transparent panels. The north wall can remain solid and painted white to reflect light back onto plants. Sketch a layout showing where you want growing beds, a potting bench, shelving, and a walkway.
Estimated time: 2 days
Remove Siding and Prepare Framing
Remove the siding from the walls that will become transparent — typically the south wall and one or both side walls. Keep the structural framing in place (studs and headers). If the roof will be partially glazed, remove roofing material from the south-facing slope while keeping the rafters intact. Inspect all framing for rot or damage and replace any compromised lumber. Treat all remaining wood with a weather-resistant sealant or exterior-grade paint to protect against the high humidity environment of a greenhouse.
Estimated time: 3 days
Install Polycarbonate Glazing Panels
Twin-wall polycarbonate panels are the best choice for a shed greenhouse conversion. They are lighter than glass, virtually unbreakable, provide better insulation than single-pane glass (the twin-wall air gap acts as insulation), block UV while transmitting 80% of visible light, and are easy to cut and install with basic tools. Cut panels to fit between studs using a circular saw with a fine-tooth blade. Attach panels to the framing using polycarbonate H-channel connectors between panels and U-channel caps on exposed edges. Seal all edges with aluminum tape to prevent moisture and insects from entering the flutes. Use self-drilling screws with rubber washers to attach panels to framing without cracking.
Estimated time: 5 days
Install Ventilation System
Ventilation is critical — without it, a greenhouse overheats in summer and develops disease-promoting humidity. Install two types of ventilation: roof vents or a ridge vent at the highest point to let hot air escape (hot air rises), and a lower intake vent or louvered wall vent on the opposite wall to draw in cool air. For passive ventilation, automatic vent openers ($25 to $50 each) use heat-sensitive wax cylinders that expand and open the vent when temperature rises above a set point — no electricity needed. For active ventilation, a thermostat-controlled exhaust fan ($60 to $150) mounted high on the end wall automatically activates when the greenhouse exceeds your target temperature.
Estimated time: 3 days
Build Raised Growing Beds and Potting Bench
Build raised growing beds from rot-resistant lumber (cedar or pressure-treated pine). Beds should be 8 to 12 inches deep for most vegetables and herbs, and no wider than 4 feet so you can reach the center from either side. Line the bottom with landscape fabric to prevent weeds while allowing drainage. Fill with a greenhouse growing mix: 60% topsoil, 30% compost, 10% perlite for drainage. Build a potting bench along the north wall — a sturdy work surface at waist height with shelving above and storage below for pots, tools, seeds, and soil. The potting bench is your greenhouse workstation and will be used daily.
Estimated time: 4 days
Install Shelving and Vertical Growing Space
Maximize growing space by using the vertical dimension. Install wire shelving units or wooden shelf brackets along the side walls for seedling trays, small pots, and herb containers. Hang hooks from the ceiling rafters for hanging baskets and grow lights. The floor-level beds handle large plants (tomatoes, peppers, squash), the shelves handle smaller plants and seedlings, and the hanging space handles trailing plants and supplemental lighting. This three-tier approach can triple your growing capacity compared to floor-only growing.
Estimated time: 2 days
Set Up Irrigation and Water Management
Install a drip irrigation system connected to a timer for automated watering. Run a main supply line from an outdoor spigot to the greenhouse, then branch to drip emitters at each growing bed and shelf level. A basic drip system costs $50 to $150 and eliminates daily hand-watering. For water management, ensure the greenhouse floor has adequate drainage — gravel over landscape fabric is the most common greenhouse floor because it drains freely and retains moisture for humidity. If your shed has a solid floor, slope it slightly toward a drain or the door. Add a rain barrel outside the greenhouse to collect roof runoff for free irrigation water.
Estimated time: 3 days
Add Season Extension Features
To use your greenhouse year-round in cold climates, add thermal mass and optional heating. Thermal mass: place several 5-gallon black water jugs along the north wall. They absorb heat during the day and release it at night, moderating temperature swings by 5 to 10 degrees. Heating: a small electric greenhouse heater with a thermostat ($50 to $150) prevents freezing on the coldest nights. Insulation: add bubble wrap insulation to the north wall and any glass sections during winter months — it traps an air layer that reduces heat loss by 30 to 50%. Row covers placed directly over plants inside the greenhouse provide an additional 4 to 8 degrees of frost protection.
Estimated time: 2 days
Materials
| Material | Est. Cost | Required |
|---|---|---|
| Twin-Wall Polycarbonate Panels (6mm) | $600 | Required |
| Polycarbonate H-Channel and U-Channel Connectors | $80 | Required |
| Aluminum Sealing Tape | $25 | Required |
| Self-Drilling Screws with Rubber Washers | $20 | Required |
| Automatic Roof Vent Openers (2-3) | $100 | Required |
| Thermostat-Controlled Exhaust Fan | $100 | Optional |
| Louvered Wall Vent | $40 | Required |
| Cedar or Treated Lumber for Raised Beds | $300 | Required |
| Landscape Fabric | $30 | Required |
| Greenhouse Soil Mix (topsoil, compost, perlite) | $200 | Required |
| Potting Bench Lumber and Hardware | $150 | Required |
| Wire Shelving Units (2-3) | $150 | Optional |
| Drip Irrigation Kit with Timer | $100 | Required |
| Garden Hose and Fittings | $40 | Required |
| Gravel for Floor (if replacing solid floor) | $150 | Optional |
| Exterior Wood Sealant or Paint | $60 | Required |
| Electric Greenhouse Heater with Thermostat | $100 | Optional |
| 5-Gallon Black Water Jugs for Thermal Mass (6-8) | $40 | Optional |
| Bubble Wrap Insulation (winter) | $30 | Optional |
| Hanging Basket Hooks and Grow Light Fixtures | $80 | Optional |
Permits
Building Permit (check local requirements)
Some jurisdictions require a permit for modifying an outbuilding structure. Many do not require permits for sheds under a certain size (typically 120-200 square feet). Check with your local building department.
$150