A greenhouse is a permanent, walk-in structure with a rigid frame and glass or polycarbonate glazing, built for year-round growing with climate control and engineered snow and wind ratings. A cold frame is a low, unheated box with a clear lid, best for hardening off seedlings and growing hardy greens. A hoop house is a series of arched hoops covered in greenhouse film that gives you a lot of growing space on a budget, but the film needs replacing every few years. A polytunnel is the UK and European name for the same type of structure. If you want to grow through winter, protect tender plants, or have a space that lasts for decades, a greenhouse is the best long-term choice.
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Ask five gardeners what a hoop house is, and you'll probably get five different answers. Some will describe a few PVC hoops over a bed of lettuce. Others will picture a long plastic tunnel on a farm. A few will just call it a greenhouse.
The mix-up makes sense. Cold frames, hoop houses, polytunnels, and greenhouses all use the sun to keep plants warmer than they'd be in the open garden. But only one of them is built to be a permanent growing space you can step into on a January morning, and that difference shapes everything from what you can grow to how long your setup will last.
A greenhouse is the only one of the four designed to be a more permanent, walk-in space you can grow in all year. The others are great at stretching your season. A greenhouse gives you one that doesn't have to end.
Instead of film stretched over a hoop or a lid on a box, a greenhouse has a real frame, rigid glass or polycarbonate glazing, a door, vents, and a foundation. It's a structure engineered to handle your climate, not just fair weather.
If you’re just getting started, the Sunhaven shows how much a small greenhouse can do. This 8x8 model has 6mm twinwall polycarbonate glazing, a frame in white, green, or brown, and an interior bolt track system for hanging baskets, shelves, or grow lights. It’s ready to ship and rated well beyond what a typical store-bought kit can handle.
If you live with heavy snow, the Cape Cod Series is built for it. Its steep 45-degree roof helps snow slide right off, and the extra height makes room for long rows of hanging baskets or even young trees.
If two or more of these sound like you, it's worth looking through your options. Our online pricing tool takes less than 2 minutes, and you don't need to share any contact information.
A cold frame is a low box with a clear lid that sits on the ground or on a raised stand. It has no heater. It relies on the sun to warm the soil and air inside, and on its walls and lid to hold the warmth after dark.
Think of a cold frame as a mini greenhouse for a single bed. It's too small to walk into, but it's very good at a few specific jobs.
Cold frames heat up fast. On a sunny day, even in cool weather, the inside can get hot enough to stress your plants within a few hours, so you'll need to prop the lid open and close it again before evening. Space is the other limit. Low crops and seed trays fit well, but tomatoes and peppers won't, and you'll always be working from the outside.
Many gardeners start with a cold frame and keep it even after they add a greenhouse. It's the perfect spot to harden off the seedlings you started inside.
Other Cold Frame Options - Lee Valley Double-Walled Cold Frame
If you prefer a traditional ground-level design, Lee Valley’s Double-Walled Cold Frame has an aluminum frame and double-walled polycarbonate panels that insulate against frost and stand up to snow. The top panels slide open to reveal a built-in insect screen for easy venting.
A hoop house is a row of arched hoops, usually metal or PVC, covered with greenhouse film. They range from low tunnels that sit just over a garden bed to walk-in structures, often called high tunnels, that are big enough for a market garden.
Hoop houses are popular because they give you a lot of covered space for the money. If your main goal is growing more vegetables over a longer season, they can be a practical place to start.
Greenhouse film breaks down in the sun and usually needs replacing every few years. A single layer holds much less heat than rigid glazing, so winter growing is limited unless you add a second layer with an air gap. Heavy snow can make film sag, strong wind can tear it, and venting usually means rolling the sides up and down by hand.
That upkeep is why many hoop house growers eventually move to a greenhouse. The growing space is similar, but the structure takes care of itself.
Start small with low tunnels. If you aren’t ready for a walk-in structure, bend a few hoops over a bed, drape Charley’s Crop Cover over them, and pin it down. A tool like Johnny’s Quick Hoops bender makes even hoops easy.
Mostly, yes. "Polytunnel" is the term you'll hear in the UK and Europe. In North America, the same structure is usually called a hoop house or high tunnel. Both are arched frames covered in plastic film.
Polytunnels are often sold as complete home garden kits, with doors at both ends, a timber base rail, and anti-hot-spot tape that protects the film where it touches the hoop. The First Tunnels 10ft Wide Polytunnel is a typical example.
Whatever you call it, the trade-offs are the same as a hoop house. You get plenty of space for the price, along with film replacement, manual venting, and more exposure to wind and snow than you’d have with a greenhouse.
| Greenhouse | Cold Frame | Hoop House/Polytunnel | |
| Typical size | Small backyard to large estate | Single bed or bench | Garden bed to market garden |
| Walk-in? | Yes | No | Yes (low tunnels are not) |
| Covering | Glass or polycarbonate panels | Polycarbonate, glass, or plastic lid | Greenhouse film |
| Covering lifespan | Many years | Several years | A few years |
| Climate control | High | Low | Low to medium |
| Winter growing | Yes, with the right glazing and heat | Hardy greens only | Limited without double layers |
| Snow and wind rating | Engineered and rated | Varies | Varies, often low |
| Warranty | Lifetime frame warranty (BCG) | Varies | Varies |
| Best for | Year-round growing and a space to enjoy | Seedlings and hardy greens | Large crops on a budget |
Start with what you want to grow and how long you want to grow it.
Most gardeners don’t start with their dream setup. They start with a cold frame on the patio or a few hoops over a bed, and before long they want more space, more control, and more months in the garden. That’s usually when they call us.
When you’re ready, request a free catalog to see what’s possible, get a quick price with our online pricing tool, or reach out to our team at hello@bcgreenhouses.com or 1-888-391-4433. We’ll help you find the greenhouse that fits your space, your climate, and the way you love to grow.