Greenhouse advice sought from SoCal, Southwestern folks
 

Hi all:

I've been growing a handful of cattleyas under shade cloth for 10+ years now. I always intended to build a greenhouse (probably a kit, possibly the Harbor Freight one) but never felt I could swing the cost...but...I'm giving it serious thought now, especially after seeing a thread here on the board about Orchidbyte's 6'x8' backyard greenhouse, which looks great to me (I can't seem to add a link without the board rejecting my post, though?).

I'm in Los Angeles, so the problem is high summer heat and low humidity. Could anyone who has a hobby greenhouse in a hot, dry environment comment or give advice on their preferred cooling systems, misters/foggers, reflective shadecloth, etc? I know people do have orchid greenhouses here, I'm just having trouble finding info specific to this environment.

Also: can you comment on the monthly costs of running those systems? I'm under the impression that the cost of building the greenhouse itself will be a lot less than running all of the equipment...

Thanks, I appreciate it.

Consider a trial period with a hoop house built from 1" or thicker PVC irrigation pipe and landscape plastic. If you like it you can build something more permanent. Your weather is mild, so something like this will be fine. It might not require a building permit.

Evaporative coolers work well when humidity is low. Check your weather forecast. When the dew point is below 55 F they work well. They use water so rationing may be an issue.

Shade cloth will be mandatory. Not many orchids grow in full sun in habitat. Here in Phoenix many people use Aluminet, saying it helps reflect heat as well as light.

An electric space heater should suffice on cool winter nights. A fan running constantly is mandatory. Spring for a high quality temperature and humidity sensor.

^^ What he said...

I am in texas, hot and dry summers....I run a mister (jaybird 700) set on a humidistat, and an evaporative cooler....I had an extra humidistat so I put it on that as well...I think that it should actually be on a thermostat...that's in the works for next summer....lots of fans, and an exhaust fan larger than required working with passive intake shutters.....its a delicate balance here, as the summers can stay at over 100 degrees for days on end....evap coolers are inexpensive, and work great!

Ok, thanks for the responses. If anyone else has any thoughts/input I'd be grateful to hear them.

Can't help with the question, but to post links you need minimum 5 posts. One more post and you're good to go!

Ah, I see. Thanks!

hi darby, hows the plan coming?....I built my last couple greenhouses with cedar and polycarbonate....both lean-to designs I just made as I went, lol....I grabbed all the space I was allowed on our lots!
my bf is understanding what I used to say all the time, no matter how big it is, IT IS NEVER BIG ENOUGH! lol....
I had a couple in florida too, with double plastic, and that was always a mess....one with that corrugated stuff...the polycarb is definitely the way to go!
cedar wood is good to work with, for me anyway...it smells nice, and is easy to cut...I like screwing things together as it is more secure...
if you bide your time and wait for sales, the polycarb isn't that expensive....
good luck and let us see photos of your job!

I cool my little GH (was a kit, put it up about 10 years ago) with an Aquafog 700 fogger on a thermostat. (I live in Costa Mesa) It works beautifully - temperature rarely goes much above 85-90 deg F. (Our relatively low humidity makes it quite efficient) I also use a direct-vent gas heater (costs more than an electric one but costs A LOT less to operate) I did that after fighting to maintain temperature in the great freeze of 2006-2007, where I found that the most efficient 1500W 110v heater could not keep up when temps dropped to the low 30's F. Fans are the cheapies from Home Depot that are Vornado copies (cost about 1/3 as much) They last 2-3 years, the expensive ones don't last much longer. So go cheap.

Hi, thanks for checking in--well, the plan's coming very slowly, between various projects/life/etc. But now I'm trying to make some progress.

I've also been trying to figure out if a small greenhouse or an indoor orchidarium makes more sense, though I'm still leaning towards a greenhouse. This is all complicated by the fact that the only space I have to build on is on a 6" thick concrete slab (that can't be easily/cheaply removed without a jackhammer) and so I won't be able to bury water/power lines and have to bring in water via hose from a distant spigot. I'm not sure if that qualifies as a 'problem' or not.

I'm interested in your cedar/polycarb greenhouse, do you happen to have any build pictures by any chance? I assumed a kit would be cheaper to build in the end...but I have built a shed that's still standing and I'm not afraid to try going DIY. I can screw things together with the best of them...

---------- Post added at 06:14 PM ---------- Previous post was at 06:02 PM ----------

Thanks for your note--does the Aquafog qualify as an evaporative cooler? I wasn't clear on that based on briefly looking at its description online. My impression from doing research on the forum here is that I'll need a combination of evaporative cooling and a fogging system. Do you use the Aquafog mainly for temperature control, or does it also help raise the humidity?

Heating, I haven't given it as much thought as I probably should. Since it usually doesn't freeze here I tend to be a bit complacent--but during the big 2006/07 freeze I happened to be out of town and overnight went from a collection of 40 orchids growing outdoors down to, I think, 4.

The upside of that was that I learned which ones are the hardiest.

PVC pipe on the top of the slab can be used for protecting an extension cord from the elements and from being stepped on. Also, PVC pipe can be used to bring water from your hose bib to the GH (again on top of the slab) My last home was a condo with a patio, and I managed to create a whole sprinkler system above the slab (tapping into one side of a Y connector on the hose bib, so I could still use it for a hose as well.) A bit mickey-mouse, but it worked. (My watering encouraged -horror of horrors- moss growing on the front steps, however, generating a nastygram from the association that convinced me that I needed a house with a yard...where I am now) For heat, you can also use a portable propane heater using a 20-lb cylinder that is used for barbecues. The only disadvantage of that solution (other than the need to keep track of gas usage so that you don't run out in the middle of the coldest night) is that you have to manually turn it on and off, where a built-in heater can use a thermostat.

---------- Post added at 06:22 PM ---------- Previous post was at 06:15 PM ----------

The Aquafog provides a fine mist which cools as it evaporates and raises the humidity at the same time. You can run it on a humidistat to maintain a particular humidity, or a thermostat to maintain a desired temperature. I find that the GH stays plenty humid from the fogger plus watering, so I don't pay much attention to that factor. I'd rather have it running longer (and maybe getting things pretty damp) to keep temperature down. Extra humidity when it's hot is no particular harm that I can see. You can run it from a 5 gallon bucket if you are able to stay on top of keeping it full, but I think it would be worth the trouble to run that pipe over the slab so that you can provide it continuous water (I use the benchtop version. It has a reservoir with a float valve to control water flow so then requires no attention to keep it supplied)

Got it. Ok, thanks, that's very helpful.

The PVC suggestion is good, too, I hadn't thought of that. This makes sense.

Side question: you mentioned that you built a kit GH, can I ask which one you went with? Do you like it?

I don't recall the name, but the company is no longer in business for some years. I have a friend who has a Harbor Freight GH and is quite happy with it.

Yeah, if I go with a kit, that's probably the one I'll use. Good to know it's worked out for your friend.

Sorry, stupid question, but is your Aquafog connected to an outside vent, or is it entirely inside your GH?

No question is stupid! The Aquafog is completely within the GH... here is a link http://neutronusa.com/prod.cfm/811771

This price is better... Jaybird didn't used to sell direct but apparently now it does
Products / Hydro SS Series / Bench Top | Jaybird Manufacturing

You may be able to find it for a better price... these things aren't cheap but then, neither are orchids. It just takes water from its reservoir, and pulls it through tiny holes in the propeller part, blowing a lovely cool fog. Totally self contained.

Great, thank you. This helps a lot.

building on a slab isn't impossible....and running a water pipe is really easy, if you can diy...trench it a bit tho....

polycarbonate is readily available in 4 foot widths...so you put your studs up to accommodate that....our building skills are pretty limited....so what we do is to set the corners in 4 x 4's...and with our heavy heavy winds, I used a 4 x 4 post 'every other one'...the rafters are 2 x 6...
cedar is more expensive, but the only option with wood is treated, and I hate that stuff....the sun exposure warps it awfully bad....
so, we set the corners, then put up one sheet of poly at a time, then fasten the stud down or rafter....one at a time! you don't want to mess one measurement up and have to detach and re-do....
I lay down the poly and dry fit it, then use a bead of silicone caulk to hold it...once I have two sections, I go over it with 1 x 4 cedar to 'trim' it, and screw that down. if you put a fresh bead of caulk down, and screw into that, it seals nice.
go back thru this greenhouse forum, and you will see how we did our last two...
with cement pads, you have to lay down a 'sill'...put a good bead of liquid nail down and use one of those things that fire a 'bullet' into cement to permanently fix it...
my greenhouses are pretty stout...I think the house will blow away before my greenhouses, lol...

Actually, the slab is a good foundation. And if you plumb in water and power, the pipe and conduit help hold the while thing down (those anchors suggested by dounoharm are also good idea) it isn't going anywhere in a wind. I do think that since electricity and water don't play nicely, that the power is worth getting an electrician to run.A separate circuit is worth the investment. (And you never have too many outlets... fans, fogger, electric heater all need them.) Water is easy - and pipe can easily sit on top of the slab.

actually, you could lay a row or two of cement block on the slab, and then put down a sill..then you could put some gravel over top of the slab for extra humidity....I like to run my water to the evap cooler and the mister thru copper pipe to avoid stepping over it, then cover that with gravel...keeps it from being stepped on and leaking...it is truly amazing how that gravel on the floor helps with humidity!

Ok, good, thanks for the tips. I need to take a look at some more greenhouse build threads, I'm sure it will clear up some of the things that still seem a bit abstract to me.

Read read read read read
Think think think think think
Plan plan plan plan plan

Planning, of course, yes. Although my problem tends to be that the more I ruminate on this kind of thing, the more likely I am to only see problems and talk myself out of the whole thing. It's probably better to just drink a lot of beer and solve problems as they arise...

A number of people here have very kindly offered to let me come tour their backyard greenhouses in the area--LA is very spread out, and various time constraints mean that I can't easily get to all of them, but I think this will answer a lot of my questions.

Hi, I tried all that stuff with my 6'x8' here in Los Angeles, the only way to grow with our hot and dry conditions is a swamp cooler, it will cost you 50.00 every two months of summer and it will do the job. Misters, foggers just keep things to wet, you have to have air flow, fans and a swamp cooler, under table misters that are linked to a irrigation valve to a multi program controller, can pick that up cheap at big box store.

I find that with my GH stuffed with 85 pots on table all in large chunk gravel, 135 mounted and normal plants in the ground under tables works great. i water entire GH once a week and feed all through year, will mist mounts every other day in heat.
I use 50% aluminet from Apr. - Oct., full sun no shading rest of year.

Installed a hot water line that I can mix with filtered water so I don't put freezing cold water on warm plants in morning. I just use a whole house filter system to water plants, seems to work fine, plants have excellent roots.

Below are pictures of GH when I cleaned it a few months ago, empty. with pots in and then with all mounts.

Beautiful greenhouse, and great advice.

X 2

I want to mention that Orchidbyte very kindly invited me and the family over to see his greenhouse last month, which was extremely helpful (to me). Before the visit I was going back and forth between building a greenhouse or an orchidarium and now I'm definitely going greenhouse.

I still have a ton of details to work out but now I feel like it's actually do-able, whereas before I wasn't sure. It also helped to bring the family along because now they're enthusiastic about a GH too, and actually want it to be bigger than I originally planned...so, again, thank you, it was a big help.

The axioms of greenhouse growing:

1) When erecting a greenhouse, always go bigger.
2) It's already not big enough.

Yeah, I can see that. Orchidbyte impressed on me that although his 6x8 obviously works well for his plants, it's not big enough for more than 1 person to squeeze inside at a time. I have enough room on my site to go 8-10' wide, 12' long.

Also, go for height... give yourself room to hang things without needing to do gymnastics to get through the GH, because lots of things are especially happy when they can hang.

Yeah, I can see that too. I'll definitely keep that in mind.

At this point I'm looking at pros/cons of a kit versus building a wooden (I assume cedar) frame, DIY. Annnnd I still need to figure out a foundation for my building-on-top-of-a-concrete-slab situation. All of the kits/plans I've found so far assume that you're working with a patch of bare earth, which I'm not...

Another vote for height, but for a different set of reasons.

The lower the surface-to-volume ratio, the more stable the interior environment will be, year round. A cube is better than an elongated structure, but not as good as a geodesic dome.

With added height, you get significant differences in light levels, based upon the distance from the glazing, as the glazing is the "source" of the light, and inverse-square still holds true (although the size of the "light" is huge).

Concerning the slab, that really shouldn't be much of an issue. A decent carbide-tipped drill bit to make holes, and expanding anchor bolts to attach the base to the slab is really all you'll need.

I would use cinder blocks as base, build wall 3 to 5 high, fill holes with concreate, you might want to add some rebar, drill holes in slab and insert rebar, make sure you chip some of the cinder blocks to put a 2" or larger PVC pipe so you have drainage out. Paint wall with a waterproof paint, Put GH on that wall and there you go. I do know a great mason that is inexpensive if you need, also know electric and plumber guys as well, since I'm a landscaper, it all comes with the trade.

It will cost you more to build your own GH then to get a kit, the headaches with building from scratch are numerous. At least with a kit you get a warranty. Make sure you can get electrical and plumbing out there easy enough, make sure Electric is on its on circuit, since it will have to run fans, heaters and a swamp cooler or 2 depending on size of GH.

If you need any help I'm only a stones throw away.

Excellent, thanks. I have an electrician and plumber but they're not always available, so I may have to ask for your guys.

Yeah, a kit probably makes the most sense. I like the idea of building from scratch but the chances of screwing it up up seem high.

My last greenhouse (#5) was the only kit I've ever had. It looked nicer than the others, which were all made from pressure-treated lumber, by the way, but frankly, there's very little to "screw up", if you're reasonably handy with tools.

Hmmm. I'd say I'm reasonably handy, yes (I managed to build an 8x10' shed from a kit that's still standing) but I've heard more than one person say, like orchidbyte, that building from scratch would cost more in the long run than just going with a kit. What's your take on that?

I looked through the Roger Marshall "How To Build Your Own Greenhouse" book and it suggested using pressure-treated lumber coated with (I think) marine-grade epoxy and paint as an alternative to cedar/redwood--did you do something like that?

A consideration on DIY in southern California - termites. Pressure-treated wood is quite resistant, redwood pretty good, cedar not so good. Since we don't have hard frost, termites have a field day. (Essentially all houses need fumigation after 20 years or so, greenhouses are warm and wet and have issues sooner).

Good point...

Do-it-yourself has always been less-expensive for me. I'm not sure what might make it more, longer term. However, the Turner Greenhouse kit looked a great deal better than anything I constructed. Maybe if I had been concerned about covering up glazing joints and the like, it would have added up, but I was more concerned about function than appearance early on.

My use of lumber was always unpainted, treated lumber, I even used it for tiered benches, and it never hurt any of the plants. In fact, I ended up replacing the wooden benches with polymer ones, because the roots didn't "grab" the plastic as well, making them easier to separate without damage.

a commercial cut flower operation I worked for in California used a copper based 'paint on' treatment every couple years...I think that is no longer available (anything that really works gets changed, lol)....also, most of the houses there were up on a 'knee wall' of cement block....

I built a knee wall here in texas also, because I love to use cedar....the legs of my benches are treated, but the top is cedar....

its very satisfying to be able to say, 'we built it ourselves'....and I always have at least one 'mistake' bravely shown....lol...