Our high mountain desert can be a challenging climate for the spring garden. It also makes growing your own starts difficult.
Germination is the first stage in starting the early garden. Our drastic climate, in the Treasure Valley, where, during winter, nights get as low as 0 degrees germinating can be tricky. There are as many methods as farmers for germinating as early as possible. This is how I do it and my thinking behind what I do.
The key to germination is not light, but soil temperature. Even light dependent seeds won’t germinate if you can’t get the soil up to temperature. I used to set up a “grow room” with a 1000 watt halogen light, heater and silver emergency blanket walls. This method is way too energy intensive. I abandoned the “grow room” for a germination table and germination room. No artificial light. I heat the bottom of the table and thus heat soil. For frost tolerant plants air tempaeture isn’t as important as soil temp. The room doesn’t need to reach 70 degrees, just the dirt.
For the first three years of this new method I simply used a tile-surfaced kitchen table up against the interior south facing wall of my trailer. I have three huge windows that face south so I positioned my table up against this wall and put my flats on the table. I placed a space heater under the tile table top. For hot crops I would put up fabric walls around the table legs. Everything is seeded in order of it’s resistance to the cold. I start with alliums first, next brassicas then lettuce and so on.
As soon as the flats show signs of green they are moved from the germination table to the germination room. The germination room is a greenhouse built onto the south facing wall of my house. It happens that my front porch faces south so the germination room is a glass house built onto the front porch. This room is not directly heated. The only heat besides the blazing daylight is the passive heat of the house. On very cold nights I leave the window open between the grow room and the house letting the heat from the house heat the germination room. Mostly this just cools the house down.
This is why every seeding is done according to tolerance to the cold. Alliums are the hardiest of the spring crops and can handle being frozen after germination so they are done first and are barely protected from the outside temperature.
Two key things: 1. South facing means direct sun all day. No shade at any time. Nor is the sun dappled. No other amount of sun will suffice. If there is a tree in the way cut it down, it’s that important. This is why most people use an artificial light source 2. Neither plastic, nor glass, can insulate against temperature in the low 20’s. In the Treasure Valley you must “heat” your greenhouse to keep hot crops alive. There are tricks, but just having a greenhouse doesn’t mean you can grow Meyer lemons or even keep peppers alive in April.
My germination table is a box measured to fit exactly 24 flats. The box has 4 galvanized steel sinks to capture water and channel it into a container where I collect the water. This water is then fed to my worm box. The sinks are covered by removable frames with wire mesh centers. All the exterior wood is cedar treated with linseed oil. I still put a space heater under the box to heat the soil.
Things you can do to help keep plants alive during cold nights is to use a greenhouse inside a greenhouse or cover plants with floating row cover at night. The next dangerous thing is that during the sunny winter days the germination room can get very very hot. Again, I open the windows between the house and glass room circulate cooler air from the house into the room. Sometimes I leave the outside door open. Constant monitoring is required. Check dampness of flats by touching soil not just by looking. So far so good! –Farmer Marty