All in a day's work

When I started making plans to start my seeds indoors again and decided to sterilize (bake) the seed starting medium I already had on hand, visions of this scene popped in my head – an old fifties ad with a put-together woman in pumps and an apron, single-handedly managing to keep a clean house, cook a balanced meal for her family, and prepare soil for the seeds she'll cultivate for her family's future meals. An ad that convinces housewives everywhere that sterilizing their own soil is a snap. You can have dinner on the stove and your soil in the oven and both will be ready in a jiffy!

Actually, it was a pretty easy process and since I'm trying to use as many sustainable gardening practices as possible, re-using soil I already have makes a lot of sense. Using sterile soil is critical for healthy seedlings. Most garden supply stores or nurseries sell sterile seed-starting medium, so if you're starting out with that, you're already good to go.

To sterilize used seed-starting medium:

1. Spread the soil on a baking sheet. The soil should be moist, but not too wet. I moistened the soil and mixed it around a bit to make sure that it was moist throughout and not just on the surface.

2. Cover the baking sheet with foil and put in a preheated oven set at 200 degrees. I have an oven thermometer in my oven so I was sure that my oven wasn't hotter than what I set it at. Gauging temperature during this process is pretty important because over-heating the soil can produce plant toxins.

Here is the slightly tricky part. According to my Master Gardener handbook, the goal is to get the soil to a temperature of 140 degrees and keep it there for thirty minutes. In other resources, I read that it should be 180 degrees, but no higher than 200 degrees. I set the timer for 10 minutes, then pulled it out and checked the soil temperature by inserting a meat thermometer in the center of the pan, right through the foil. I found that I had to do this several times before the soil temperature registered 140 degrees. Once I got the soil to 140 degrees, I set the time for 30 minutes. When I checked the temperature after 30 minutes, it was registering 170 degrees, but since it was still below the 200 degree range, I think I'm OK.

3. After 30 minutes at 140 degrees, take the pan out of the oven and let it cool. Keep the foil in place – the smell of fresh baked soil is not nearly as appetizing as bread. Trust me on this.

4. Finally, make sure you sterilize the container you're going to use as well. I used a very diluted bleach and water solution to clean out the flat that I use to start my seeds.

That's all there is to it. Just a few simple steps and you're on your way to a bountiful harvest. Now isn't that swell?