Rose Greenhouses/glass houses

I am thinking of building a greenhouse/glass house for some of my roses and seedlings. I was wondering if anyone had photos of their structures they could post and how/if such a structure, meant for roses and raising seedlings, would be different to other more general structures? The purpose of the structure would mainly be to get seedlings growing and away from late frosts, give me more room to do it, keep them away from animals, and protect them from the almost constant strong winds we get… Tasmania sits bang in the path of the Roaring Forties and we get hammered for most of the year… they are freezing in the winter and drying in the summer. The temperature here can get fairly high (low 30’s (Celcius)) and down to about -7 in winter and whilst I can put power into it I would be keeping it low tech.

I should add I have an area of about 5m x 10m I can use for it.

I’ve had a pseudo-solar greenhouse 9 x 12 ft for 25 years. It adjoins my house on a S-SE orientation (northern hemisphere). Kalwall for the roof, sliding glass patio doors for walls. Roof pitch 30 which is below what Kalwall recommends for their Al-framed 4 x 8 ft panels, but we have very little snow load here. A couple hundred gallon jugs of water on rear wall and under benches, circulating air into the subsoil through 4" drainage pipe with a computer fan on top, 1 inch rigid insulation panel to go in at night for cold. When temps are going below -7 C I use a 1500 W vornado brand heater for supplement, set to hold 40 F, (4 C). You might get away with nothing if you have sun every day and no long period overcast and cold together. Flexible insulation is easier than rigid. Air driven styro beads between layers of Kalwall are basically a failure, as shown by our local UFM.

There are a million variants on solar greenhouses out there. The water and rock or soil ballast is key to temperature control. You don’t say if this is free-standing or adjacent to a structure. Adjacency saves one wall, on the cold windy side if you’re lucky. Consult books, on-line or perhaps someone in your area doing solar for vegetable growing.

For benches I have old coldbox metal wire shelves on a wood frame (movable all together). Concrete reinforcement mesh works OK but tends to sag under load. In winter a wire shelf at 1 ft, over water jugs, and another at ~4 ft both are well illuminated. As days lengthen of course the upper shelf shades the lower.

Orientation is key to solar efficiency. A freestanding house ought to have the ridgepole point to solar mid-day line. A leanto wants the perpendicular of that.

The sliding doors are a good priced structural solution. IN summer I open wide, unless we are getting a full gale which is very common in KS (> 15 mph much of the time). Screens keep out bugs, but not determined creatures. In time the double-glazed doors will fog making diffused light. Not such a bad thing for most plants but too low light for good rose growing. Kalwall yellows over time and by 15-20 years loses its polyester surface unless you recoat. We never had the cool, cloudy day prescribed for that except one year in November, so I didn’t very well on that.

Thanks Larry,

I guess I should have been more specific… I have a design (well two actually…) in mind already but what I’m mostly after was whether there are any ideas or design considerations that work better than others for growing roses, as opposed to other crops, inside a greenhouse given roses are essentially an outdoor plant prone to fungal problems. I have designed and made all kinds of greenhouses before for plants but others here in Australia have had lots of trouble with fungal diseases in their greenhouses and I was wondering whether this kind of thing could be minimised with more effective design?


I work in several “poly hoop” greenhouses, most of which are 20 X 48 feet. After 10 years working in these environments I am convinced that it is impossible to simulate outdoor growing conditions in a greenhouse. Just the fact that the plants are sheltered under plastic influences their behavior. Roses often behave and LOOK quite different once you move them out of a greenhouse and into the open air garden. You have to provide extra air movement or Mildew may ruin ALL of your work; this is a BIG factor in maintaining rose health in an enclosed space.

A greenhouse (even mine, which are unheated) will extend your growing season by eight weeks or more per year, and this is a big advantage. Even without heating in the Winter the houses provide significant protection to tender plants.

The space you say you have for this structure is quite small (5 X 10 feet?) this will allow enough room only to germinate seeds and grow on a few seedlings up to the one gallon container size. A dozen three year old seedlings will eat up that much space pretty quickly!

I will take some photos of a couple of my houses for you next time we get a sunny day, or maybe upload a video to YouTube if you want.



Thanks for the reply Paul,

The space I have to work with is in metres, so that would work out to be about 16ft x 32ft.

I have two designs I am thinking of. The first, my preferred design, is a free standing structure running east-west, with the narrow ends facing east west. There are three reasons for this. The first is that the sun rises in the east and sets in the west and in winter is much lower in the sky towards the north so facing my largest area towards the north will allow me to capture as much sun as possible during the winter. The second is that the prevailing winds are very strong and come from the west. If I face the sides with the least area to the west then I’ll be able to reduce the impact of the wind on the structure. The third reason is linked to this. I’m thinking of putting a door (I like Larry’s idea of screened sliding doors) in the east and west side (the two narrow ends) so that during summer I can open them both up and because they face the prevailing winds I’ll get excellent through-flow of air through the greenhouse to cool it down and minimise humidity. I was thinking of having an inverted asymmetric ‘V’ shape roof with the half facing the north having a larger area than the half facing south so I can make the area facing the sun in the winter quite large. I was planning to make a simple box frame around the base about 30cm (nearly 12 inches) high and slightly larger than the perimetre of the greenhouse. I’d then build the greenhouse in this frame and fill it in later with black gravel to act as a heat sink during the winter. They call it blue-metal here… it’s not metal but is a basalt-type rock and in sizes of about 5mm it beds down nicely, drains well, and is soft to walk on. If the ends are left open (but screened) during the summer I should be ok as far as over heating goes but I’d put some vents or lourves in the top to allow for the exchange of hot air by convection. I think I will need to have some kind of shade cloth curtain to stretch across the top to cut down the sun during the summer. I think I’ll be using some kind of polycarbonate sheeting if I can find it for a reasonable price so I can put power in it for lighting though I like the look of those solar lights you can get that would work well in this location and mean I don’t need to hook power up to it. I have a very large spanish chestnut tree (deciduos) on the western side that will provide a little shade late in the afternoon and will act like a baffle and buffer the wind a bit.I was hoping to have two 5ft wide benches running up the middle of the greenhouse so there is a 2ft walkway right around each bench and so that when the doors are open the wind passes straight over the top of them.

The second design is a lean-to type greenhouse to go against the corrugated iron wall between my two chicken coups. It’s a fairly large wall about 4 metres long and a good 2-3 metres high with an area of ground about 8 metres in front of it… well I can remove the fencing and extend into the back paddock but it is not as level as the other site. The wall faces east and gets morning sun to about 12-1pm and then is shaded in the afternoon. This is great for summer but it would only get sun for half the day in winter compared to all day at the other site. It would be cheaper to build it here but not as warm in the winter.

I’ve had these two designs in my head for a while now and was even entertaing the thought of building both of them so I could use the first one to grow the parent plants and do pollinations in and the other to germinate and raise seedings in… that idea will have to wait for a while though. I thought I’d get on here first and run these by people more experienced than me (which is almost everyone :slight_smile: ) and see if these sound Ok for roses or if I’d need to make some changes to suit them better.

Another person I know here has problems with a black sooty mould and black spot on her greenhouse roses. I think the sooty mould is due to having an aphid problem and the honeydew they produce then coats the leaves and stems and provides a food source for this particular fungi and the aphids seem to thrive in closed environments. I was reading on your site Paul about the zip-lock bag method of propagration and have been using it with good success this year. On one set of cuttings of Felicite et Perpetue I must have missed an aphid because when I checked the bag a few weeks later the cuttings had a thriving population of aphids on it.

I was wondering, also, what’s the best kind of way to water roses in a greenhouse (both seedlings and larger plants)?

I just saw the offer of photos and a video and would LOVE to see this either way it is more convenient for you…

I was thinking of polytubes but am worried the wind here would shred it to pieces.


I live in a place that is often hammered with VERY strong afternoon winds most days of the Summer, but the poly greenhouses stand up to it very well. In fact, I usually get two years more life out of the poly than the manufacturer suggests!

I will work on a YouTube video today, if I can.


Our local school district just (last summer) installed five of the poly high tunnels at local schools. There are two others I know of in town, in use for years. Wind is not a problem, despite our location in the vicinity of the best wind power sites in the whole continent. The curvature of the tunnel lets the wind roll right over, even our routine (every week or so) 30-40 (up to-50) mph days. I don’t think you’ll need or want louvers. The sliding doors let you modulate the inflow, especially if one end faces the prevailing wind. The arching roof is a compromise for optimum solar inputs.

For winter of course you are better with a roof pitch to the altitude of the mid-day solstice sun. Polycarb is good but generally pricey compared to glass. Over time it solarizes & crazes, unlike glass. Hail breaks glass but puts defects into polycarb or Kalwall (fiberglass). Hail shreds polythene but usually only the outer layer in a double-glased high tunnel. The plastics are usually heavily dosed with UV absorbers/quenchers (typically compunds called benzotriazoles) to protect the polycarb etc. Depending on thickness and brand, they will filter little or much of the UV from your plants.

I’ve not had mildew plague my roses, except very susceptible varieties in the greenhouse, but I keep heat off until near 4 C. Certainly though Paul is right that under cover roses are rather different than in natural sun. Partly I think it’s the loss of UV, so Rainbow’s End or other photoresponsive flowers have no red, just yellow. Also it’s well documented that vibration affects growth hormones in plants, affecting the extent of stem lignification, insect and spider mite resistance etc. Vigorous spraying daily with a hose (in time to dry before dark) is remarkably beneficial to roses compared to just watering the pots.

Quartz-halogen lamps such as Sunbrella have a fair amount of UV, depending on the shield in front of the lamp tube. So do fluorescent lights, which run poorly in the cold. The halogens are richer in red/far-red, more like tungsten lamps. These ratios (UV or R/FR) matter for optimum growth habit, flowering induction of day-length responsive plants, pigment production. For maximizing photosynthesis though you can’t beat the cheapest high efficiency fluorescents. Lots of trades to make.

“Also it’s well documented that vibration affects growth hormones in plants, affecting the extent of stem lignification, insect and spider mite resistance etc. Vigorous spraying daily with a hose (in time to dry before dark) is remarkably beneficial to roses compared to just watering the pots.”

Wow… that’s really interesting… makes sense too. Thanks for the input. I will look into poly tubes… Sure would be a lot cheaper than a solid structure. It does still worry me making a plastic film greenhouse and running power for fluoro lights in it though since you guys recommended the poly tubes I have found this stuff: that looks intersting.

I have a Sunshine greenhouse, cedar with polycarbonate greenhouse walls. Stood up to 160kph winds and large hail with no problem. I don’t know if you can get them all over the world, but I’m so happy with mine I’ll be getting another shortly.


Simon, I took at look at that site. The hi tunnels we have here are much like #9100cc being over 10 ft at center. You might find under cloches, some walk-in hi-tunnel, relocatable greenhouses that would do, but a lot lower head clearance. Seem pricey to me but I don’t know NZ$.

I guess a lot depends on whether you feel like doing construction work yourself. I built for $2500 what someone up the road spent $11,000 to purchase of all glass and bronze anodized Al. But he was nearly 30 yr older than me and had the $$.

There is a group called which describes what we call a high tunnel in the U.S. There are some very nice plans for constructing one of about your needed size on another site that pops up in the google search (happens to be from KS). They are used in New Hampshire, PA, many states, and worldwide including Mongolia, some of the stans etc. Estimate is that without heating it gains you two hardiness zones in winter. So in your case it ought to prevent frost. Lots of other info on siting, orientation etc. Cost is $1-3/sq ft or $10-30/m2. But you need new poly in maybe 4 yr.

Six or so of my breeders are pretty tender, so I’m wondering how to over-winter them. I don’t have an attached garage, which some people have suggested to me, so for this winter I was thinking of building a small shelter and mounting it against the house.

I am also thinking about building a hoop-house, both to protect these plants and their seedlings but also to generally extend the season especially at the end where a few weeks makes a lot of difference.

Does anyone have experience with hoop-houses in a zone 5-6 environment who can tell me what to expect. I’m especially concerned about whether it would provide a false sense of security for the coldest winter nights.


I have a hoophouse made from 4’ x 16’ cattlepanels and covered with plastic. It’s 8 feet wide and 20 feet long. I put five of them together for the 20 feet. As far a winter protection it really isn’t the type of structude I would use. It’s only six feet tall and the plastic offeres little protection from cold. There is just too much airspace inside. It does protect plants from allowing frost to settle in the Spring.

For cold protection I would build something three feet or less in height to try and gather as much heat from the ground as you can get. You could use 3/4 inch PVC to make the hoops and pull white plastic over it. For cold protection the small amount of air space is better so go closer to the ground.

I know a grower in Ohio that will lay trees down, pot and all, on the ground after they have gone dormant for the winter and then pull a sheet of white plastic over them. Stay away from clear plastic because that lets the Suns’s rays through and can raise the temperature enough to break dormancy.

I put a link to pictures of my unfinished hoop house. I had 10 inches of snow on it last winter and it came out just fine. I am going to put some 2x4 braces on the inside this winter for a little more snow load. Wind load is unknown. I live in a very wind protected area. It could act like a parachute in a big wind.