Last Fall we purchased a geodesic dome greenhouse from some friends who were moving (they have a series of write ups about it on their blog, including how to make one of your own). They were very generous in selling it to us, and we have really enjoyed owning it.
The dome is 5.4 meters (18 feet) across, and about 3 m (10 feet) high in the centre of the dome with a 3v frequency design. It is very strong, and can easily support my weight on top, and will shed snow and support the snow load in the winter. We live in a 3a hardiness zone, and this close to the mountains we can get very late frosts in the Spring or early ones in Fall, and theoretically could get a freak snow fall at any time. Hail storms are also a problem around here during the summer. All this makes a greenhouse a very valuable addition to our gardening as it can really expand a very short growing season.
Before we could move it, the greenhouse had to be carefully taken apart, cleaned, and re-stained. We prepared the ground for it on October 26 by taking up the sod and tilling the earth.
The next day it snowed… and that snow stayed until April.
We kept the wood framing inside all winter, waiting for some nice weather to come. Once the snow melted, the base was levelled to prepare for the dome. We put concrete blocks under it to keep the wood off the ground.
This is a time lapse video that I made of the construction back in May. Don’t be fooled by it. Despite the four seasons seen in it, this was done over the course of an evening and a Saturday in mid-May.
Greenhouse Time Lapse from Troy Johnstone on Vimeo.
Putting the skin on – a special greenhouse quality, UV resistant poly.
Digging the hole for the water tank. The tank is on the north side of the greenhouse, right next to the door (just off the right side of the picture). By burying the bottom of the tank, it gives it the strength to hold in the immense water pressure. The purpose of the water tank is to provide some thermal inertia, if you will. It absorbs heat during the day, and helps keep the greenhouse warm at night. I have some water hoses that circulate water around the base of the plants. In the spring, that water hose can be more than 10C warmer than the air around it at night.
Painting the water tank. Ellie made her own old-timey bonnet.
To keep the greenhouse from overheating, there are four self-opening windows, two down low and two near the top of the dome. As the openers get warm, the hydraulic cylinder pushes the window out. We mounted a fan that is controlled by a timer on one of the top windows to force more hot air out the top. Once the sun shines on the greenhouse for awhile, the windows start opening up like petals on a flower.
Greenhouse set up and first plants in the ground! This photo was taken on May 22, 2014 – a bit of a late start because of the construction of the dome. The tomatoes were planted a bit too close together… live and learn.
The greenhouse fits in nicely in the back half of the backyard. The house had some large perennial flower beds when we bought it, and we have tried to keep them up, but we are slowing changing some of the landscaping over to foodscaping – landscaping with a purpose.
We had the greenhouse set up for about a month before we left on a 3.5 week trip to Ontario and New Brunswick! Thankfully, Naomi’s parents were able to keep an eye on the greenhouse in our absence. Here is how it looked when we left (June 23). The milk jugs are there to absorb heat during the day and radiate it back to the plants at night, which can get pretty cool this close to the mountains (between 7 and 13C, or 44F to 55F), even in July and August.
And when we got back on July 17:
We hung up some frost cloth on the south side to block a bit of sun and help cut down on heat a bit. On a cool day it can still get over 30C (86F) in there, and a hot (for here) day of 30 C it gets around 37C (97F) inside.
When we left for our trip we had one plant coming up that we didn’t recognize. It just had two big leaves, and looked similar to the broccoli that we had growing in there. We figured we would leave it there and see what it was when we got back. Well, we were surprised to return the next month to discover a giant canola plant! Not sure how that seed got in there…
The greenhouse is an important part of our gardening. Inside we have:
Lots and lots of tomatoes. The ones above are roma tomatoes.
Garden fresh herbs – rosemary, oregano, 2 types of sage, 2 types of basil, and thyme.
We are very thankful to have it to protect the crop from nasty weather as the greenhouse has already withstood many rain and hail storms. The plastic isn’t really tight and has enough give in it to bounce off most hail, but if it gets extreme it will probably get shredded. I have seen hail around here strip the vinyl siding off of a house..
It is too hot right now, but later we will try planting some lettuce in the greenhouse so we can hopefully have fresh greens, hopefully right into mid to late fall.
We have already been enjoying eating quite a bit of fresh food from our green house, and are looking forward to the harvest to come. Along with the rest of the gardens, we have had some very tasty and nutritious home grown food!
Update: Yes, it can handle the snow.
Update 2: Check out our Subterranean Heating and Cooling System!
Love your greenhouse! You did a great job!
where can I find the window openers?
Thanks and love your green house!
Thanks! We purchased the Ventguard Auto Vent Greenhouse Window Opener on ebay: http://www.ebay.ca/itm/Ventguard-Auto-Vent-Greenhouse-Window-Opener-2-Springs-Type-QH320-/221437415582?ssPageName=ADME:L:OC:CA:3160
Do you heat the greenhouse in the winter? Can you share some temperature comparisons(inside vs outside)?
I forgot to ask, approximately how much did your project cost?
Unfortunately, we can’t heat the greenhouse in the winter, it just isn’t worth it. We live in a 3a hardiness zone, with winter temperatures regularly in the -15 to -30 C ( 5 to -22 F). But even in the winter it is usually about 5 to 10 degrees warmer, depending on the snow cover of the dome. I usually don’t bother to brush the snow off. Today is a cool April day, and the outside temp is about 2 C or 35 F, and it is 29 C or 84 F in the greenhouse.
We purchased the greenhouse from friends for only $300, but have sunk a few hundred more into it for our subterranean heating and cooling system, stone walkway and a few other pieces. I’m not sure how much they spent on the materials originally.