Step 5 - Greenhouses
Planta Greenhouses: An Honest Assessment
A heavier structure than the mass-market kits, sold on a different model. That changes the buying decision as much as the specification does.
Janet H. - the hands-on owner behind Janet Media Group.
Published - last updated
This page contains affiliate links. If you buy through them we may earn a commission at no cost to you, and it never decides what we recommend. How this site is funded.
Planta sits above the mass-market kits: heavier structures aimed at cold climates, sold direct by the manufacturer rather than through general retail. That distribution model is a real part of the decision, because it changes lead times, shipping and how you handle a problem.
Direct-sale versus retail
| Direct from manufacturer | General retail | |
|---|---|---|
| Lead time | Often longer, and seasonal | Usually in stock |
| Shipping | Freight, sometimes curbside only | Standard carrier or store pickup |
| Spares | From the manufacturer | Often also from the retailer |
| Returns | Manufacturer's policy | Retailer's policy, usually simpler |
| Price comparison | Harder -- fewer sellers | Easy |
None of that makes direct purchase worse. It does mean planning further ahead, checking what the freight arrangement actually includes, and understanding the returns position before ordering something that arrives on a pallet.
What heavier-duty buys you
In cold-climate greenhouses, weight is specification. Heavier-gauge framing and closer rafter spacing carry snow load; thicker glazing holds overnight heat. Those are exactly the attributes that separate a structure that survives a hard winter from one that is a three-season proposition.
If you are in a Cascades-type climate -- wet winters, real snow, long cool springs -- that is the specification to buy at, whichever brand supplies it.
The alternatives you can buy today
If you want a heavy-glazed structure available through normal retail channels, the 10 mm twin-wall models in the mainstream ranges are the closest equivalent. They are lighter than a premium direct-sale structure, and they are the practical answer for most buyers who need something this season.
Quick picks
| # | Product | Best for | Score | Price |
|---|---|---|---|---|
| 1 |  Top pickPalram Canopia Glory Greenhouse10 mm twin-wall polycarbonate throughout | Cold climates and winter growing | 8.9 | 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 |  Min/Max Greenhouse ThermometerRecords the high and low since last reset | Knowing what actually happened overnight | 8.6 | Check price on Amazon |
#ad We may earn a commission - prices are shown by Amazon, not by us
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.
Questions to ask before ordering any premium greenhouse
- What is the snow and wind rating, and does it match your location rather than an average?
- What does the freight include -- curbside drop, or placement? A pallet on the street is your problem to move.
- What is the lead time, and does it land before or after the season you want to use it?
- How are spare panels supplied, and what do they cost? Glazing is the part that gets damaged.
- What base does it require? Heavier structures often need a prepared base, which is a cost on top of the kit.
For the cold-climate specification generally, see greenhouse kits for winter. For the mainstream range, the Palram Canopia review.
The picks in full
Top pick
Palram Canopia Glory Greenhouse
Palram Canopia
#ad We may earn a commission - prices are shown by Amazon, not by us
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 |
A first real greenhouse
Palram Canopia Mythos Greenhouse
Palram Canopia
#ad We may earn a commission - prices are shown by Amazon, not by us
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 |
Knowing what actually happened overnight
Min/Max Greenhouse Thermometer
Various
#ad We may earn a commission - prices are shown by Amazon, not by us
The cheapest accessory that changes decisions: it tells you the overnight low and the midday high, not the temperature at the moment you happened to look.
Every greenhouse decision -- when to sow, when to vent, whether you need a heater, whether the frost cloth is doing anything -- depends on a number most owners never measure: the overnight low inside the structure.
A min/max thermometer records the high and low since you last reset it, so a morning glance tells you what happened while you slept. That turns guessing into knowing, for the price of a bag of compost.
Hang it at plant height and out of direct sun. A thermometer in a sunbeam reports the sunbeam, not the greenhouse.
What works
- Shows the overnight low, which is the number that kills plants
- Cheap enough to put one in the greenhouse and one in the cold frame
- Tells you whether venting is working
- No installation
What does not
- Reads wrong if hung in direct sun
- Digital versions need a battery
- It measures, it does not fix anything
Skip it if: nothing. If you own a greenhouse and not one of these, you are guessing about the only variable that matters.
| Type | Min/max recording thermometer |
|---|---|
| Reading | Current, plus high and low since reset |
| Mounting | Hangs at plant height, out of direct sun |
| Power | Digital models take a single cell |
Common questions
Are Planta greenhouses worth the price?
They are aimed at cold climates where heavier framing and thicker glazing genuinely matter -- snow load and overnight heat retention are structural questions, not preferences. Whether that premium is worth it depends on your winters; in a mild climate it buys capability you will not use.
Where do you buy Planta greenhouses?
Primarily direct from the manufacturer rather than through general retail. Plan for freight shipping, check whether delivery is curbside only, and confirm lead times against the season you intend to use the greenhouse in.
What is a good alternative to a premium direct-sale greenhouse?
The 10 mm twin-wall models in the mainstream retail ranges. They are lighter than a premium structure but carry the glazing thickness that matters for winter heat retention, and they are available through normal channels with simpler returns.
What should I check before buying a heavy-duty greenhouse?
The snow and wind rating against your actual location, what the freight delivery includes, the lead time against your growing season, the cost and availability of spare panels, and what base the structure requires -- a prepared base is a real cost on top of the kit.
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.