Step 5 - Greenhouses
Greenhouse vs High Tunnel
One is a building with a floor plan; the other is a cover over the ground. That difference drives everything else.
Janet H. - the hands-on owner behind Janet Media Group.
Published - last updated
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A high tunnel -- also called a polytunnel or hoop house -- is a film cover over hoops, and it covers far more ground per dollar than a rigid greenhouse. A greenhouse holds heat better, lasts longer and works as a building. For a home garden the choice usually comes down to whether you want area or permanence.
| High tunnel | Rigid greenhouse | |
|---|---|---|
| Cost per square foot | Much lower | Higher |
| Covered area for the money | Large | Small |
| Overnight heat retention | Poor -- single film skin | Better, especially twin-wall |
| Cover life | A consumable, replaced periodically | Panels last many years |
| Growing style | Crops in the ground, in rows | Benches, pots, staging, and in-ground |
| Wind and snow | Vulnerable unless well built | Better, if anchored and rated |
| Permanence | Semi-permanent | Permanent |
Quick picks
| # | Product | Best for | Score | Price |
|---|---|---|---|---|
| 1 |  Top pickQuictent Portable Walk-In GreenhouseSteel tube frame with reinforced PE cover | The cheapest usable start | 7.8 | Check price on Amazon |
| 2 |  Palram Canopia Mythos GreenhouseAluminum frame, 4 mm twin-wall polycarbonate | A first real greenhouse | 9.0 | Check price on Amazon |
| 3 |  Palram Canopia Glory Greenhouse10 mm twin-wall polycarbonate throughout | Cold climates and winter growing | 8.9 | Check price on Amazon |
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Scores are our own editorial judgment, formed from published specifications and independent sources. They are not aggregated customer ratings, and they are not the result of hands-on testing, which we do not currently do. See how we choose.
Where a tunnel wins
Area. If your goal is to cover several beds and grow in the ground under protection, a tunnel does it for a fraction of what the equivalent glazed footprint would cost. For anyone growing at volume, that is decisive.
It also goes up faster, needs less site preparation, and can be moved -- some growers rotate a tunnel between plots across seasons.
Where a greenhouse wins
Heat retention, durability and working comfort. A single film skin loses heat quickly overnight, so a tunnel runs closer to outside temperature than a twin-wall greenhouse does. For seed starting and shoulder-season protection, that difference matters.
A greenhouse is also a building: shelves, benches, potting space, somewhere to store tools and stay dry. A tunnel is a covered piece of ground.
The film is a consumable
Greenhouse film degrades under UV and is replaced periodically -- a recurring cost and a recurring job that rigid panels do not have. Budget for it, and buy proper UV-stabilized horticultural film rather than generic sheeting, which fails far sooner.
For a home garden
Most home gardens are better served by a greenhouse. The areas involved are small enough that a tunnel's cost advantage does not dominate, and the greenhouse's heat retention and working comfort matter more at that scale.
A tunnel makes sense when you are covering several beds of in-ground crops, or when you want a large covered area cheaply and accept replacing the cover. A walk-in tunnel cover is the small-scale version of the same idea.
The picks in full
Top pick
Quictent Portable Walk-In Greenhouse
Quictent
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A tunnel, not a building -- but the cheapest way to find out whether you will actually use a greenhouse before spending real money.
This is the honest entry point. A lot of people buy a greenhouse and discover they do not have the habit to use one, and finding that out cheaply is worth something.
It does real work in spring: hardening off seedlings, protecting young plants from a late frost, and giving you somewhere dry to pot up. Those are the jobs a first greenhouse actually does.
Treat the cover as a consumable and stake it properly. Every bad review of a tunnel greenhouse is a wind story, and almost all of them start with skipped guy ropes.
What works
- A fraction of the cost of a rigid kit
- Goes up in an hour with no special tools
- Packs away out of season
- Mesh windows give usable ventilation
What does not
- The cover degrades in UV and is a replaceable part
- Poor in wind unless properly staked and guyed
- Not a snow-load structure
Skip it if: you are in a windy or snowy spot. A covered frame is not a structure, and covers are a consumable.
| Frame | Powder-coated steel tube |
|---|---|
| Cover | Reinforced PE with mesh windows |
| Sizes | Several walk-in footprints |
| Ventilation | Roll-up door and mesh side windows |
| Anchoring | Ground stakes and guy ropes supplied |
A first real greenhouse
Palram Canopia Mythos Greenhouse
Palram Canopia
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The sensible first greenhouse: an aluminum frame with twin-wall panels, sized to fit a normal backyard rather than a nursery.
Twin-wall polycarbonate is the thing that separates a greenhouse from a plastic tent. Two skins with an air gap between them insulate, and the panel diffuses light rather than throwing hard shadows, which suits seedlings better than clear glass does.
The Mythos sits at the point in the range where you get a proper aluminum frame, a roof vent and a lockable door without paying for the heavy-duty glazing. For starting seeds, hardening off, and stretching the tomato season at both ends, that is the right specification.
Two warnings from the manual that people ignore. Anchor it -- every lightweight greenhouse that ends up in a neighbor's yard was not anchored. And build it with a second person; the panels flex and the frame is not square until the last bolt.
What works
- Twin-wall panels diffuse light and insulate better than single-skin plastic
- Aluminum frame will not rust or need painting
- Lengths let you match the run to the space you have
- Roof vent included rather than sold as an extra
What does not
- 4 mm glazing is thin for real winter use
- Assembly is a long afternoon and genuinely needs two people
- Must be anchored -- an unanchored kit is a sail
Skip it if: you live somewhere with heavy snow load. 4 mm panels are a three-season specification; the thicker-glazed models exist for a reason.
| Frame | Rust-resistant aluminum |
|---|---|
| Glazing | 4 mm twin-wall polycarbonate |
| Sizes | 6 ft wide, several lengths including 6 x 8 and 6 x 10 |
| Ventilation | Roof vent, lockable door handle |
| Base | Integrated base rail, anchoring required |
Cold climates and winter growing
Palram Canopia Glory Greenhouse
Palram Canopia
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The heavy-glazed model in the range, and the one to buy if the plan is to keep growing through a real winter.
Glazing thickness is the whole argument for this kit. A 10 mm twin-wall panel holds substantially more heat overnight than a 4 mm one, and overnight is when a winter greenhouse either works or does not.
It is also the model to look at if you get real snow. Thin panels and light frames are a three-season specification; if you are in the Cascades or anywhere with a genuine snow load, buy the heavier structure rather than hoping.
None of that makes it heated. A greenhouse without a heat source holds a few degrees over outside, which is the difference between hardy greens surviving and not -- it is not a tropical house in January.
What works
- 10 mm glazing holds heat far better than 4 mm
- Rated for harder weather than the lighter kits
- Wider footprint gives room for benches down both sides
- Better vent provision as standard
What does not
- Substantially more expensive
- Thicker panels cut light transmission a little
- Heavy enough that assembly is a two-person, whole-day job
Skip it if: you only want a spring seed-starting space. You are paying a large premium for insulation you will use for three months of the year.
| Frame | Heavy-gauge aluminum |
|---|---|
| Glazing | 10 mm twin-wall polycarbonate |
| Sizes | 8 ft wide, several lengths |
| Ventilation | Roof vents, and a screened side vent on some models |
| Base | Integrated base, anchoring required |
Common questions
What is the difference between a greenhouse and a high tunnel?
A high tunnel is a film cover stretched over hoops, with crops grown in the ground beneath. A greenhouse is a rigid structure with glass or polycarbonate glazing. Tunnels cover far more ground per dollar; greenhouses hold heat better and work as buildings.
Are high tunnels warmer than greenhouses?
No. A single film skin loses heat quickly overnight, so a tunnel runs closer to outside temperature than a twin-wall greenhouse. Tunnels excel at covering area and keeping wind and rain off, not at retaining overnight warmth.
How long does high tunnel plastic last?
The cover is a consumable that degrades under UV and is replaced periodically. Proper UV-stabilized horticultural film lasts considerably longer than generic sheeting, and budgeting for replacement is part of the true cost of a tunnel.
Is a high tunnel worth it for a home garden?
Usually only if you are covering several beds of in-ground crops. At home-garden scale the cost advantage does not dominate, and a greenhouse's heat retention, staging and working comfort matter more. Tunnels come into their own at larger areas.
Sources
Factual claims on this page are backed by the published sources below, and product specifications are the manufacturers’ own. Where a figure is not published, we say so rather than estimating it.