Sadly no running water other than getting a longer hose that could reach from the spigot on the house, but I do have some spare rain barrels I was planning to put next to the greenhouse as a source of water.
Electricity is good, I’ve got an electrical box already in the garage that allegedly is a 30 amp circuit, but sadly the home inspector when we bought the house said the wire that’s run out from the house really maxes out around 20 amps, but that still should be plenty.
For humidity, I have an 800w warm mist humidifier, but that thing is expensive to run regularly on anything but the lowest setting. Luckily for us, humidity in winter isn’t a problem usually… ambient is usually 80-90% relative humidity all winter. Summer gets bone dry, though. As an example, here’s the nearest public weather station to my house over the last 7 days, humidity is the green line:
water holding capacity of air goes way up with temperature. so 90% humidity air at 50 degrees F, when you take that same air and heat it up to 90 F without adding or removing water, will be maybe 30% humidity
Mike,
How hot does it get inside the greenhouse in July/Aug? How about the humidity? Do you have any fruit trees in your greenhouse? How do they respond to the summer heat?
Put them inside, not outside. Make a hose going through the wall so you can fill them up. Been inside they will warm up on a sunny day and work as small heater at night. And even if that is not significant, you don’t want to use cold(if not freezing!) water for watering and don’t want to open the door during winter to bring water in.
Humidifier for what? I run the humidity in mine as low as possible all yr long. In spring it’s regularly below 10%. I’ve seen 1% outside and the greenhouse is drier than outside during the daytime. Never has that caused an issue with anything. It just makes sweeter fruit. Low humidity is a huge plus for disease management both on the fruit and the tree. Disease is non existent in mine.
Also my greenhouse wasn’t over 95 more than briefly all last year. And we had nonstop sun and heat to 103F. I don’t know why people build greenhouses that aren’t functional. Mine at 1725 sqft has three 36 inch exhaust fans but only needs two running to hold low 90s when it’s 100 outside. That’s in conjunction with a wet wall for evaporative cooling. The fans don’t cost much to run as they only have 1/4 hp motors. The fans don’t cost more than $20 a month to run and my greenhouse has ideal temperatures 24/7/365.
On a 320 sqft greenhouse the proper fans and a wet wall shouldn’t cost but $5-10 per month to operate and you’d be set. They run automatically. No forgetting and ending up at 130F when you least need it.
My next greenhouse, if there is one, will be setup the same way but with the addition of solar panels and batteries. Fully automatic and I can be gone for a month with no freezes or over heating.
I’m guessing that in winter the greenhouse roof will easily capture enough to keep them full, the ones attached to 1/4 of my house roof fill up after the first few rainy days of fall. Perhaps one of the greatest benefits of that infamous Seattle rain is how it comes slow and steady all winter.
I’ll probably have to supplement with tap water during the summer months (dry season), but many of the plants will be out on the patio near the hose by that time.
Do you know of a good guide or design for building the type you have? I could just google it, but I’m sure there are many ways to do it and yours sounds effective.
edit: Also, what kind of trees do you grow? My understanding is some tropicals need pretty high humidity for healthy leaf growth, and I’ve read studies about greatly increased pollination rates for avocados with high humidity vs dry climates (flowers dry out quickly and cease being receptive to pollen). Though avocados do prefer dry air for most of the rest of the year, I gather.
The critical part is the water reservoir. That’s the weak link on mine. At 28ft long it came in sections and the joints soon leaked. On a 320 ft GH you’d only need about a 5ft wet wall and that tank should be one piece. There are other systems using stock water tanks as the reservoir.
Call a good supplier and they could get you set up with the right sizes for your greenhouse, climate, and temperature needs.
The wet wall is on one end and the exhaust fan/s on the other end. Exhaust fans are efficient because you are removing the hottest air and replacing it with the coolest which is thru the wet wall. Even here in Texas the wet wall is mostly for when it’s 70F or warmer outside and sunny. Otherwise just the fans do well enough. Right now with fruit trees in full bloom I’m holding 80F my day and 40s at night.
Humidifier for my vegetables and citrus and whatever I’m cloning at the time. I empty my greenhouse sometime in May- drag all my potted citrus and figs outside as well as the window boxes I overwinter. It’s a bit of a relief honestly to get a break from all the watering. I don’t know that I want to run it in the summer as I need my spare time for my garden and outdoor fruit trees. I only grow in pots and I sell off 90% of what’s in my greenhouse in March and April so it’s easy to shut down.
The garage-to-greenhouse conversion is underway. We’ve reached the end of demolition, next up construction begins. I say “we” but after my last home improvement project gifted me with neck surgery I’m letting the professionals handle this one.
That looks like progress.
I think that will make you a nice greenhouse.
I would recommend putting in diagonal braces ,
These could be steel straps , cables , etc.
I take it you’ve spotted the temporary/makeshift braces they put on after things got a little wobbly during demo
They picked up a big stack of lumber today for framing the rear wall & reinforcing the existing walls & roof. I’m optimistic that it’ll be pretty sound by the time they finish that part, and the 8mm twin-wall panels will likely add a bit of stability to the walls as well once they are screwed in place…
They sell flat steel strapping like a inch wide and ~ 20ft long for bracing, hurricane straps . Can do a X with it on the walls,nailing it to the top and bottom plates and studs.
Or strong strapping can be sourced from a dumpster at a brick / block company for free. Need a good heavy punch to make holes in it for nails.
These straps will really stiffen up a building , cheep. Not much material to create shade, will help with wind load too.
I would want it to be very ridged before putting polycarbonate panels on .
Good luck
The contractor has been paid, and now it’s my turn to focus on all the final details like sealing up all the drafty bits, furniture selection, lighting/heating/humidifier, flooring (gravel and maybe a few pavers), and of course plant placement.
As you can see, there were some X braces added (thanks for the suggestion @Hillbillyhort), though he ran out of the strapping without doing 100% of the walls, and none of the local big boxes had more in stock, so we decided this was enough, at least for now. They were installed on the inside of the frame to allow me to add more later in the same style if I notice any swaying/instability, without needing to remove panels to do so.
QUESTIONS
What would be the least-ugly but still effective method of sealing up the bottom edges where the panels meet the structure and around windows/doors?
The contractor attached the U-brackets to the bottom of some of the panels (not all ) and H-brackets between them, but there are many areas with small gaps where those meet the concrete foundation or wooden frame, or where the H connector was cut slightly too short () leaving gaps where you can feel the air coming in at the bottom of the panels when the wind gusts. Some examples:
I have quite a few extra panels, so one thought I had was to cut horizontal strips and then adhere those along the outside base with silicone so that they seal up the entire bottom.
I know some people use those cans of expanding foam, but I’m worried those will look bad and I’ve already been told by the guardian of household aesthetics that the greenhouse is too ugly from the contractor’s bad paint job and excessive use of foil tape. (More foil tape is maybe another option, though?)
Does anyone have recommendations for a durable, affordable thermostat that I can use for both heating and cooling?
I don’t plan to have any heavy duty heating, maybe just a small electric heater (500w max, likely less) and I’ll have the grow lights wired to turn on with low temperatures as well to add a little more heat (500w max, likely less).
For cooling I have an auto-open roof vent, two doors and two windows I can manually open, but no active cooling at this time. I still would like a thermostat that would let me add an exhaust fan later if needed.
There seem to be a number of different options with a pretty wide range of prices. For example, here’s what I believe is a known brand that seems durable, but expensive and requires some wiring:
Here’s another option, seems less known and maybe less durable but much quicker to set up and a lot cheaper:
And there are many others, too.
What’s the easiest way to set up some degree of automated watering during vacations/travel?
I’m worried about automating watering for a 3 week trip we have planned later this year. In the past for small indoor gardens I’ve used small pond pumps like this one in a large reservoir hooked up to a timer that waters once or twice a week for a few minutes with small sprayers along the tubing, and that’s my tentative plan here with a rain barrel that I’ll be putting in the greenhouse soon. However, I’d love to hear any other suggestions!
Thanks again to everyone who’s helped me figure out the best way to do this!
Regarding watering, I might suggest looking into the ‘wicking tub’ concept. I’ll toss in a link to one of ‘Gardening with Leon’s’ videos, specifically on fruit trees, since you mention avacados. Far as I can tell he’s the OG when it comes to wicking tubs. I haven’t tried one of these for fruit trees myself, but am preparing to this year. Last year I grew tomatoes in one, and it seemed to work well. You could have the same pump on a timer fill the tub a couple times while you’re gone.
Regarding the auto-open roof vent (I’m assuming it’s of the ‘wax-filled piston’ type that uses heat expansion to open it) you may possibly find it to not be effective enough if you don’t also have an equivalent intake vent that opens at the same time. I don’t have a greenhouse myself, but have been researching to build one, and my understanding is that natural ventilation such as through a high vent like that will work much better if it has an equal opening low to let in air to replace the vented air.
For sealing the gaps, I’d say silicon. It’ll be the closest to matching your clear panels, I’d think. For the gap like above the door, where it’s not bordering on a panel, you might consider expansion foam, trimmed down after it dries. The stuff cuts very easy with a knife after it has cured. You could smooth off the rough edges, and cover it with foil tape or something else to hide the yellow foam. Or you could just get some of the painted foam quarter-round trim from a big box store, in white, silicon and tack nail it up there.
I have a similar greenhouse in its first season and I found I needed fans to keep it cool enough. vents need to be enormous (like whole roll-up sides) to be enough on their own. I ended up with about 500 watts of fans in addition to huge vent openings on the opposite side, for a 380sqft greenhouse to keep it within 10 degrees F over ambient. it’ll get easier/cheaper once I set up intake misting. same idea as a swamp cooler except you directly mist into the air. I forget the industry term for this but it’s a common enough method. we have relatively low humidity here on warm days so it should work great
my thermostats are esphome/home assistant which is a DIY programmable system. I can’t recommend it unless you already like to fiddle with toy electronics like arduino/raspberry pi stuff
for watering I did ordinary drip irrigation with a couple zones and various emitters (mostly micro sprayers, some overheard spinners, and mist heads for propagation). same idea as an outdoor drip system
I might have two pi zero w’s (with camera modules, hardwired together for a binocular vision experiment), an OG raspberry pi (collecting dust on the shelf), a raspberry pi 3 (old school video game emulator for the kids), and a raspberry pi 4 (waiting to be used). I was planning to use a pi with two sensors (this one and this one) wired to the GPIO headers to keep a log of temperatures, maybe the pi 4 or one of the zeroes. I’ve never messed with arduino, but been on my list of things I’d like to try.
I was afraid that might be the case, but I did also get doors with screen panels I can swap out in the summer, so I’m hoping one exhaust fan up in the gable will be enough with screen doors and open windows, but I understand that might not be the case.
I was assuming that I’d be around to open it up or just leave windows open during the summer, but you’re right that ideally I want it to be more automated. An intake fan instead of exhaust maybe?
I do this for seedlings in small trays sometimes, but never thought to try it for larger trees. Thank you for the suggestion!
) and H-brackets between them, but there are many areas with small gaps where those meet the concrete foundation or wooden frame, or where the H connector was cut slightly too short (
