I didn't realize how long it's been since I posted an update, there are a few updates to share.
Based on how thing were warming up this spring, I decided to starting growing on March 15th this year. That's 10 weeks earlier than my last frost date outside. The week before that I ran the climate battery fan only on warm days to bank some heat. After March 15, I set it up to run at night to keep things from freezing. Here's what I have growing at the moment:
- overwintered seedlings that will go outside later (kept inside to ensure no winterkill):
- sedum
- thyme
-gayfeather
-caragana
-chives
-6 black locust (an experiment, I have another 20 that I moved outside, so I'll see this fall what kind of advantage this 6 gained)
- new seedlings:
-2 50 cell trays of coneflower
- 1 50 cell tray of hyssop
- half a tray of gayfeather
- brussel sprouts and kale for outdoor planting
-vegetables in raised beds:
-broccoli
-tomatoes
-bell peppers
-melons
In terms of building/construction, it's done yet but as my hobby continues, progress has been made.
The ceiling, north wall, and half the side walls are now insulated, sealed, and covered.
I have ready many tips saying NOT to use OSB inside a greenhouse (due to the humidity). I'm going to try it anyway; I could not find any other material that seemed as cost effective. All edges will be sealed with caulking and the surfaces sealed with white latex paint.
While the walls needed a durable cover, the ceiling does not. So I capped the fiberglass insulation with 1" XPS styrofoam insulation. It was cheaper than wood AND adds another R5 to the insulation value (for a total of R32 in the ceiling). So far just one coat of paint, I'll add more after everything is taped and sealed.
I setup an automated misting system for humidity/cooling. I used an patio misting system + a solenoid valve. It's activated by a relay controlled by a "mini computer" (ESP8266). I had some creative fun coming up with a good misting cycle. Intuitively I knew that I wanted to mist more often when it was hot or dry (low relative humidity) or both. That's when I learned about "Vapour Pressure Deficit", basically a calculated number that determines exactly how comfortable any RH/Temp combo is for plants. The misting system and the climate battery fan controller both communicate wireless with temperature sensors I added, and report there statuses to an online dashboard. I could post a whole separate thread about this system so won't get into it further here other than share a screenshot. I don't aspire to have "tech" in my greenhouse, but at least this is setup is all open source and self-maintainable. To date, I have discovered that generally my greenhouse is too dry instead of too humid.
I built another raised bed and filled with a soil mix. Mainly two year old compost from our horse manure pile + lime + clay top soil + peat moss. I also added 8 gallons of biochar that I made.
Oh, and I started the task of covering the floor with woodchips. This winter showed me that a bare dirt floor is NOT going to work. I would walk accross the clean snow to the greenhouse, and once I stepped inside the greenhouse the snow would melt, with the floor and turn into mud, then I had to deal with mud everytime I came back into the house. I chose to go with woodchips because it drains well, it's free, and I don't have to worry about trying to keep it tidy. If I put in gravel, how do I clean up a spill of soil? Either soils ends staying in the gravel or gravel ends up getting added to the beds. Woodchips seemed more compatible. It's pleasure to walk on. On hot days I intentionally spray water on the chips to give a little boost to the humidity and cooling.
