Jesus was a carpenter. I’m no Jesus (even if I have a Rod complex). My carpentry is terrible. (Or maybe Jesus became the Messiah because His carpentry sucked, too). What I mean to be plumb, level and square usually turns out askew*, aslant and abysmal. While I take no pride in this disability, I am very grateful that at least I’m not building an ark. Recently I produced a cubic cubit of sawdust trying to get a length of 2X2 to fit. I kept cutting and cutting and it was still too short (with thanks to Dad for that joke; apologies to everyone else).
The current project is a bottom-heated grow box inside the propagation tunnel. Last year’s propane campstove-heated version was finicky and expensive. The flame was either too hot or tended to blow out overnight. And the heat didn’t distribute very well amongst the bottoms of all the trays.
I’m trying to scale up a version that Harry Burton built from scrap materials. Mine will hold 24 standard trays, about 4 times the size of his. Below the trays will be an 18″ cavity insulated on the floor and walls, forcing 98%** of the heat to escape upwards. It will be powered by a 900W/1500W thermostatically-controlled space heater. I’ll probably keep it at 900W so that the breaker doesn’t trip (I share this circuit with the farm house tenant’s workshop). Hopefully this will be enough juice to warm the potting mix. I have no plan B for replacing all this capacity, except hoping for more and faster global warming. Fingers crossed for new Tar Sands pipelines.
The top of the unit will have a 3/8″ hardware cloth floor and a 3.5″ plywood lip to hold the trays. Importantly, the floor and sides will be lined with polyethylene. This will allow me to top-water without worrying about soaking the heating cavity below. Better yet, I can simply fill the 3.5″ deep soaking tray with, say, kelp-water and saturate the soil.
If it works, I can see this unit speeding up the watering process 63%*** by exchanging 24 trays at a time. We spent an inordinate amount of time last year watering trays individually.
But this would require a reasonably plumb structure. And, so far, it has just not happened that way. Perhaps a prayer is in order?
* If your OS is linux-based, google has a clever result for this search term
** This is complete fabrication.
*** I’m on a roll.