Riga greenhouses?

Does anyone have experience with Riga greenhouse kits? We are looking at the XL, which has triple wall polycarbonate and based on my calculations won’t be too dear to heat. Costco has them on sale right now with an accessory package that works out to be a great deal.


looks like a nice setup. Im not sure any greenhouse is going to be less than dear- they lose heat so quickly. Our high tunnel is 32 x 48. With solawrap, it cost about as much as the Riga XL. Its a nice amount of space, but then we have plenty of elbow room here. We were going to do a 32x80 and Im glad we didn’t. Material costs went up so much, the main reason we went smaller, but it really would have been more space than we need. Im stil hoping to build sn attached greenhouse someday for cool subtropicals. Id considered using a kit like the Riga in a 1/2 width /double length configuration, but most or all Iclve seen are just too skinny. 7 ft seems to shallow to be very useful


That’s a lot of money for a small space. And worst of all it doesn’t appear to have adequate heating and cooling. That’s where 90% of small greenhouses come up short. Then they resort to shade cloth for cooling. Then they become seasonal use, only spring and fall.

For comparison I helped a guy design a big greenhouse for central CA. It’s 30x70x18ft tall. It has a 23x6ft wet wall and three big exhaust fans. Two at 36 inch and one at 48 inch. Also two NG heaters of 150K BTU. That will assure adequate heating and cooling. It’s totally covered with 8 mm solarsoft polycarbonate. Total cost for materials, 60K.


Interesting, thank you. Yes, materials costs are pretty high these days. The spot I have in mind for this is limited as it is closer to our house and I don’t want to have to take long trips in the depths of winter. I think I could fill up any size, though! I have long wanted an attached conservatory…my citrus really needs babying in our sunroom with regard to humidity and light management because it’s just not an ideal environment. At the very least we have hydronic baseboard and not drying forced air. What are you growing in the high tunnel?

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The heater is definitely inadequate. I calculated I would need anywhere between 23-38k BTUs to keep it above freezing (*or at 60 min). We are on solar and natural gas so I would probably run a gas line. My only solution for cooling beside exhaust is that it would be situated to get winter sun and summer shade (there’s a larger tree to the south of it). I had not thought a lot about cooling besides that, so that is a good point.

As much as I’m sure I could find plants and trees for a very large greenhouse, in this specific spot I’m limited…I could maybe go 20x40 max, but really as much as it pains me to say, I don’t want a massive building in this spot. If I felt I could find a greenhouse builder in my area and get a quality, commercial style (by that I mean…not cheap or poorly designed like so many of these kits) building that was not huge, I would go for it, but I haven’t found that…it seems there is a big gap between the “kits,” the glass highly decorative models from places like Hartley Botanic, and enormous commercial buildings. Is the gentleman you consulted for building it himself, or contracting it out?

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He’s an engineer and serving as the general contractor. Building it will be expensive. I imagine he’ll have 100K in it total. That’s roughly $50 per sq ft. Yikes that sounds high. But gives an idea of cost on a bigger well built unit designed for all year use.

In 2005 I built mine for ~25K at 1725 sqft. So less than $20 per sqft. Mine is nearly as well built as his.

Here’s the good part a 25K pickup bought in 2005 is nearly worthless. My greenhouse is still in very good shape and would last the right person another lifetime of growing.

Repairs and upkeep haven’t been much. I’d say $400-500 a year. Heating and cooling: 1-2K a year depending on how much I heat. Growing the best fruit I can grow, stone fruit, is actually pretty cheap. Growing mango will be more expensive.

I built mine myself at age 60 with only a couple K of hired help. It’s 32x54x16 not small.

The cheapest way to get a good unit would be to build it yourself. Anything 12ft tall and under isn’t that difficult. 16ft tall is a lot more difficult but I did it.


I guess $100k for all of that isn’t surprising these days. I have a lot to think about. There are a lot of really questionable builds floating around that either don’t seem like they will hold up or are going to be difficult with regard to temperature control.

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Where are you located? That is part of the equation with regards to temperature control.

what about light? we have weeks at a time with no direct sun many a late fall / early winter. March and April are pretty overcast too, except that when the sun DOES come out in April, it’s scorching hot since the sun is as high then as it is in August. Getting the right balance of temp, humidity, and light to actually get anything to grow through the depths of winter is no small feat. Unless that thing is a cole crop or leafy green, you have so much stacked against you, at least in my climate. @fruitnut, I expect your climate is A LOT more conducive to winter growing of tender crops. What are your HDD in youre locale? Ignoring cloud cover, the difference between our longest day and shortest day is almost 7 hrs. By comparison, central Texas seems to have about 4 1/2 hrs difference. Naturally, that corresponds with a much lower winter sun angle here as well.


I’m 95/65 in summer and 60/30 in winter with 75% sunshine all year long. This is a great climate for a greenhouse. I can achieve 900 Utah chill hours December thru mid January. The rest of the year is 90-95 for a high in the greenhouse nearly every day. It’s a rare day when my greenhouse doesn’t hit 90.

I have very good temperature control using two 150K heaters and a large wet wall plus three 36 inch exhaust fans for cooling. The wet wall even comes into play to achieve the chilling. I can get twice as much chilling in the GH as outside.

People should invest in heating and cooling systems if they want a fully functional GH.

But a greenhouse is nothing without sunshine. And heating only carries you so far if you don’t have light for the plants. The sun in winter is actually warm here with 10-11 hrs days. I often look for shade even in winter.

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Northeast Ohio, although not far north enough to get lake microclimate, the bulk of lake effect precipitation, or their worst cloud cover. Zone 6a.

That’s not the best climate for a GH. But I have seen guys in Ontario who seem to like theirs. There are videos on Youtube about their efforts.

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Im guessing you mean btu/hrs. That seems like a decent ballpark figure. Heat loss is difficult to model, especially when you include conduction to the ground as well as convection and radiation. Weve only had our high tunnel for about a year, and our only experience heating it was in mid-May, when hard frost struck this region. An 8,000 btu/hr propane heater heated held the space adequately at about 36 degrees while the mercury outside dropped to around 26. The regulator wound up frosting up, and within an hr the temp dropped to within a couple of degrees of ambient. Based on that, Im guessing your heat load is a little optimistic for your coldest night, but then most farms here that heat their greenhouses seem to use large modine type heaters or in some cases house furnaces, which cycle on/off with outputs of 100,000 or more btu/hr. Assuming your figure is good on average, what do you figure heating will cost you @Buckeye ?

Greenhouses make sense nearly anywhere, but few of us are as lucky as @fruitnut when it comes to growing through the winter. My goal for a winter greenhouse would be to have trees planted in the ground and to be able to keep the 1. alive and 2. reasonably happy during their inevitable winter dormancy. The high tunnel os great for serious season extension, and makes a great environment for growing container stuff through the (extra long, extra GDD) growing season. Long term, Id like to build an attached walipini style sunken greenhouse in which to plant kumquats, tamarillo, and some other cool season subtropicals. Id heat to keep the temp to maybe 36 minimum, and the earth berming and thermal interface with the house proper should go a long way toward stabilizing the temp swinga that are otherwise inevitable. The earth tube concept of annual thermal storage is very appealing in its simplicity, but the cost of plastic pipe is so absurd anymore that such a system is way more of a financial hurdle even then it used to be, and even then it was substantial.


Yes, hot dawg seems to be a popular heater brand. I have looked at GAHT systems and went as far as to inquire about plans from a couple places. It’s an interesting concept. The soil in this specific space is pretty crummy, which is a concern for those systems if it’s very clay. It is tempting given what people have been able to do with them, if the cost works out to an eventual savings. Cost is pretty crazy these days. The cost of natural gas isn’t too bad here right now, but of course that is also unpredictable, so it’s possible not putting in a climate battery would be a huge regret in 5 years if things change.

I would love a real attached conservatory, but our house is very old and I am mindful of how humidity would need to be mitigated to avoid causing issues. I think if we ever build a home it will be a must have, even if we have to axe something else to do it.