On our farm, projects start with internet research and often use odd pieces of “junk” we’ve got hanging around.
One winter’s projects was a germination chamber.
Some of our seeds require light to germinate but most vegetable seeds don’t. They do need consistent moisture though.
Many growers use a germination (or sweat) chamber to reduce:
- space that seedling trays take up before the baby plants emerge (when they all need light)
- frequency of watering (which also relates to algae growth)
Since we moved to this farm, we’ve started our transplants many different ways. In the 1st few years, we made some kind of germination chamber that always looked a bit different. In our 1st year, we stacked bread trays by our wood stove and wrapped the stack with plastic to keep humidity in.
Once seedlings emerged, over the years, we’ve moved them to hot beds, our sun porch, and now to electrically heated benches in tunnels.
A germination chamber is an enclosed area, where the temperature and humidity can be regulated. There is often some sort of tray stacking system where it is easy to see which trays have germinated and be able to easily insert and remove trays.
Some people have used old chest freezers, but as our only free chest freezer was a little too small for our purposes, we used an old wire rack and former project leftovers. Farm Hack was a good online resource for helping us design our germination chamber.
It all started like this:
A 3 foot wide by 5 foot tall wire rack (sans shelves) and a stainless steel sink.
Ideally I would have taken this to someone to weld a piece into the bottom of the sink to seal it up (might still do at some point), but opted for the cheaper option of silicone and a sink stopper.
Fortunately, the spacing of the supports for the shelves worked with most of the trays that we use (the 50 cell Winstrips are our tallest trays).
For the shelving I used ½” EMT, (galvanized electrical conduit), and then made a little notch with an angle grinder at both ends to fit over the wire supports. We can easily remove them so the shelf spacing can be bigger for the Winstrip 50 cell trays, or to add more than 3 bars per shelf (4 is better for the flimsier trays).
I decided to recess the sink and slope the sides because of comments other builders had made about water pooling on the bottom.
Copious tuck tape to ensure the water finds its way back to the sink and not through to the floor.
Originally, I was planning on using the Durostat prewired thermostat, purchased online from Farmtek/Growers Supply, but procrastinated a little and needed one faster than what ordering one online would bring. Luckily enough, our nearby plumbing and electrical supply place, Eddy Group, carried this dandy cooling/heating thermostat that mostly gets used for chicken barn applications. It ended up being about $20 cheaper (plus no shipping costs), and pretty simple to wire up.
So here is the beast.
Germination chambers are also called sweat boxes…for good reason. It’s quite moist in there, and there’s a lot of dripping.
My design wasn’t perfect. The water droplets on the door leaked out and onto the floor. A quick improvement was to use some tuck tape to create a little baffle so the drips go further into the box where they run into the sink.
We tried covering the water pan with metal sheeting to see if it would limit the sweating effect while still radiating heat into the box, but removed it because it seemed it would use more power to heat the box.
Although we don’t add water to the pan too often, a water line and float valve would be good. You don’t want to forget to refill it.
It’s not professional-looking but it works pretty well, saves space, and removes worry over trays drying out pre-germ.
Here’s a re-cap in pictures of how we built it: