Stepping Up Our Seed Starting Game
Starting seeds can be a tricky business. A seed will only germinate if it stays at the proper temperature and humidity for the right length of time. Get it wrong, and the seeds could come up unevenly, succumb to mold or disease, or never even come up at all!
There are several ways to keep seeds happy while they germinate. Many people use an electric heat mat underneath their seed trays, which radiates heat upwards and maintains the correct soil temperature. This method can be quite expensive if you are starting a large number of seeds. For the last few years we have started seeds indoors under fluorescent lamps, and kept the furnace cranking to keep the air temperature warm enough. This method used a lot of heating oil, and even with the lights on we had problems with leggy plants and mold.
This year we decided to build a germination chamber inside our greenhouse. A germination chamber is basically an insulated box with a pan of heated water in the bottom. The hot water serves the dual purpose of maintaining the correct air temperature and keeping humidity very high. Lights are not necessary in the chamber, because the plants are taken out as soon as they emerge from the soil.
A germination chamber can be very simple, and farmers have come up with several creative ways to build their own versions. One method is to put a crock pot connected to a thermostat in the bottom of an old refrigerator. I decided to build our chamber out of a set of metal shelves and some foam insulation left over from building our walk in cooler. I spent less than $100 total on this project, and so far it has worked perfectly this season.
The chamber itself is 3' wide x 3' deep x 4' tall, and is constructed of 2" rigid foam insulation reinforced with wooden boards. The foam and boards are screwed directly to the sides of the metal shelving unit. I bought a 1000 watt heating element for a water heater and mounted it through the side of a 6" deep stainless steel catering pan from a restaurant supply store. The heating element is controlled by an 1800 watt Inkbird probe temperature controller, which is basically just a power outlet with a built in thermostat. The temperature probe from the Inkbird goes into the chamber through a small hole drilled in the foam. When the temperature inside the chamber falls below a certain set temperature, the Inkbird turns the water heating element on.
So far, our germination rates (the percentage of seeds that sprout) and speed (time from planting to germination) have been far better than in past years. One of the best tips we got for using our germination chamber was to write average germination times and temperature ranges for each plant variety on the side of the chamber, as well as the planting dates of each tray inside. This helps us remember that there are plants inside, so we don't leave them in too long and end up with leggy starts!
A few more tips: remove the trays from the germination chamber as soon as the first few plants start to emerge. The rest will be close behind. Also, be sure to check the water in the pan every day, so the heating element doesn't run dry!
For our local customers: Thanks to the new germination chamber, we have been able to start a LOT more plants this year! We will have vegetable plants and flowers for sale at the farm stand in May. Stay tuned for more information!
Have you tried building a germination chamber? We would love to hear stories or advice on how to make ours even better. And if you want to build our own, feel free to reach out with any questions.