I just spent an afternoon with Jamie Quinn (from ferme la Terre Blue) staring at a thermometer, twisting a dial to the left and then a little to the right, trying to keep the temperature constant. We were heat treating seeds to sterilize any diseases hanging out on the seed coats of some tomato seeds.
This hot water treatment was a preparation step for a trial of different certified organic sprays against bacterial speck and spot in tomatoes. We wanted to make sure the seed wasn’t the source of any disease we’ll see this summer in the field. The 2 year trial is run by Club Bio-Action (an agroenvironmental club that provides extension to member farmers).
Let’s get this photo essay going
Step 1: Count seeds. I counted out enough seeds for a 75 rowfeet of each variety.
Step 2a: Place seeds on cheesecloth.
Step 2b: Wrap the cheesecloth up and close it with an elastic. Jamie marked each of these action packs with a secret series of dashes and slashes. He also marked the the seed envelopes with the same code.
Step 3: Preheat seedballs to 37.5C for 10 minutes.
Step 4: Heat seedballs at 50C for 25 minutes.
We used a waterbath provided by Club Bio-Action and a long graduated temperature. I kept my eye on the temperature for the length of the treatment slightly turning the dial up and down to keep the temperature as close to target as possible. Jamie kept me entertained with witty conversation.
You don’t need a waterbath for this hot water treatment but it sure made it easy.
Step 5: Times up! Spread the seed on paper towels to dry. We made sure to label the varieties on each sheet.
In a couple of weeks, we’ll start these seeds in the greenhouse. According to the literature, hot water treating seeds can affect long term seed germination – use them within the year!
We followed the Ohio State University Extension directions to do all the above.