How Is a Greenhouse Different From a Cold Frame or Hoop House?

Quick Answer

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.

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.

What makes a greenhouse different from a cold frame, hoop house, or polytunnel?

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.

What sets a greenhouse apart

Climate Control

Roof vents, side vents, circulation fans, heaters, and shade work together so you can hold a steady temperature. Automatic vent openers open and close on their own as the temperature changes, so you don't have to run outside on every warm afternoon

Year-Round Growing

With the right glazing and a little heat, a greenhouse can be a cool house for overwintering, a warmhouse for citrus and orchids, or a hot house for tropical plants.

Strength you can count on

Every BC Greenhouse starts with an 85 mph wind rating and a 32 psf snow load rating. For tougher climates, upgrades handle winds up to 140 mph and snow loads over 100 psf.

Built to your space

BC Greenhouses come in 2-foot increments, with thousands of size combinations, freestanding or attached, and a choice of glass or polycarbonate glazing.

Made to last

Our aluminum frames won't rot or rust, and they're backed by a lifetime warranty. Each one is designed and manufactured by certified journeyman glaziers, with permit drawings available in every state and province.

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.

You're ready for a greenhouse if:

• You want to keep growing after the first hard frost.
• You have tender plants, like citrus, figs or orchids, that need to come through winter.
• You're tired of replacing film or rebuilding after a windstorm.
• You want a space you'll enjoy spending time in, not just a cover for your plants.
• You're planning to stay in your home for a while and want something that adds to your property.

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.

What is a cold frame, and what is it best for?

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.

A cold frame is a great fit when:

• You want to harden off seedlings. A week or two in a cold frame helps young plants adjust to outdoor conditions before they go into the garden.
• You're growing hardy greens. Spinach, kale, lettuce, and arugula can keep producing long after the open garden has slowed down.
• You want to start seeds early. A cold frame warms the soil faster in spring.
• You're working with a small space. A patio, balcony, or side yard can easily fit one.

Things to watch for

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.

Victory Upright Cold Frame

$1,199.00

From our sister company, Charley’s Greenhouse & Garden Supply, the Victory Upright Cold Frame is part cold frame and part potting bench. It’s handcrafted from Western Red Cedar in Charley’s own woodshop, with 8mm twinwall polycarbonate panels to hold in warmth. The magnetized front doors open wide for fresh air on sunny days, and the whole unit sits at working height, so there’s no kneeling in the dirt.

Learn more

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. 

What is a hoop house, and what is it best for?

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.

A hoop house is a great fit when:

• You want a lot of growing room. Hoop houses can run long and wide for rows of crops.
• You’re comfortable with DIY. Most kits include the hardware and film, but you’ll source the pipe or lumber locally and build it yourself.
• You mostly grow from spring through fall. Hoop houses do their best work in the shoulder seasons.

Trade-offs to know

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.

Greenhouse Poly Cover, 6 mil UVI - 18' x 25'

$99.00

Charley’s Greenhouse Poly Cover is a durable 6 mil film that lets in over 90 percent of sunlight while holding in heat. It’s UV protected and comes in multiple widths and lengths. Pair it with Charley’s Snap Clamps to secure film to PVC hoops, or add an Inflation Blower to keep an insulating air gap between two layers.

Learn more

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. 

Is a polytunnel the same thing as a hoop house?

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.

How do they compare side by side?

Which one is right for your garden?

Start with what you want to grow and how long you want to grow it.

• “I want to grow year-round, overwinter tender plants, or have a space I enjoy spending time in.” A greenhouse is your best fit.
• “I want to harden off seedlings and grow a few winter greens in a small space.” A cold frame will do the job.
• “I want lots of growing room for a few seasons, and I don’t mind upkeep.” A hoop house or polytunnel makes sense.
• “I want both.” Plenty of our customers keep a cold frame next to their greenhouse for hardening off. The two work well together.

Choosing the cover that grows with you

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.