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Compare wooden and aluminium cold frames by their construction, glazing, lid operation and maintenance. Timber sides can offer useful insulation; aluminium can provide a light, low-maintenance frame. Neither material alone determines frost protection or storm resistance.
Table of Contents
Consider the whole frame’s insulation
The RHS notes that wooden or brick-sided frames can offer more protection from cold than fully glazed lightweight designs. However, lid glazing, gaps, ground conditions and weather also affect the temperature inside. Do not assume a wooden frame will safely overwinter every tender plant.
Monitor conditions with a maximum-minimum thermometer and have a warmer location for plants whose minimum temperature cannot be maintained. Temporary insulation can help, but may reduce light and ventilation.
Compare maintenance needs
| Frame | Checks over time |
|---|---|
| Aluminium | Loose joints, corrosion, hinges, glazing clips and stable anchoring |
| Softwood | Rot, splitting, joints and the maker’s treatment or finishing advice |
| Naturally durable timber | Sound joints and lower edges; durability varies with timber and construction |
Aluminium does not rot, but it is not maintenance-free. Timber treatment requirements depend on the species, any factory treatment and exposure. Use only a finish suitable for the structure and intended growing use, following its drying instructions. Avoid reclaimed timber with unknown treatment history for a frame in contact with edible crops.
Match glazing to the frame
Glass generally offers good light transmission. Polycarbonate is lighter and more resistant to breakage; twin-wall sheets can provide useful insulation. Acrylic is another clear option but is more brittle than polycarbonate. Compare the exact sheet thickness, wall construction and support requirements.
Do not substitute a different glazing material or thickness unless the frame can hold it correctly. Plastic sheets may need allowance for expansion and approved edge details. Ask the maker about replacement panes, seals and clips before buying a frame that may be difficult to repair.
Check the lid in use
A robust lid with safe, adjustable ventilation is more useful than a material advantage on paper. Check that it opens far enough, can be held securely and closes without strain. Follow the maker’s wind precautions.
Do not use a loose improvised stick or weights on glass to control the lid. If an automatic opener is proposed, confirm that its lifting capacity, mounting points and travel suit the actual vent.
Plan support and anchoring
A light aluminium frame may be easy to move, but must be secured for its site. A heavy wooden frame can also shift or lose a lid in wind. Use the specified anchoring system for soil, paving or the raised-bed structure, and keep all supports firm and level.
Weight alone does not establish wind resistance. Check the manufacturer’s installation and storm instructions, including when lightweight equipment should be dismantled or stored.
Choose for the plants and the gardener
Measure internal height for the plants, not just the outside dimensions. Confirm that you can reach the back without leaning on the glazing and that water drains away from pots. Opaque timber sides can shade low plants, while clear sides admit light but may change heating and cooling behaviour.
Choose the frame whose lid, access, repair parts and upkeep suit your routine. Whatever the material, ventilate early in sun and check moisture beneath the lid; a cold frame can overheat even on a cool day.
Useful products for this job
The links below open Amazon UK product searches. Check the exact item, seller, current price and compatibility before buying.
- Wooden cold frame: Can provide a compact sheltered growing space with timber sides. Check timber treatment, usable height, drainage, safe lid restraint and anchoring. Search Amazon for Wooden cold frame.
- Aluminium cold frame: Offers a light frame with relatively modest maintenance. Check glazing specification, replacement parts, sound joints and approved anchors. Search Amazon for Aluminium cold frame.
Related garden guides
- Small Greenhouses UK: Grow All Year Round – 2026 Guide
- Growing winter salad in a cold frame
- More greenhouse & growing guides
Sources and further guidance
- Coldframes and Mini-Greenhouses | RHS Advice
- Greenhouses: Choosing the Right One | RHS Advice
- Monthly gardening tips & advice – January – garden structures / RHS
Guidance researched in September 2026. The feature image is an AI-generated illustration. Product guidance is based on published information, not hands-on testing.