Portable Cold Frame Experiment

 I recently read an article about starting seeds in containers (milk jug, yogurt containers, and the like). The idea is to plant the seeds in the containers, wrap them in plastic, and stick them outside for natural light. When it comes time for planting, the plants will already be "hardened." Seemed like a cool idea.

Plastic Bin "Cold Frame"

Instead of many small containers, I purchased a plastic bin and some seed trays. It's Maine in March (Zone 5a), and I wasn't 100% sure it would be warm enough yet to keep seedlings outside. The bin makes moving the seedlings very easy.

Week One Seedlings

The trick is to keep the temperature inside the bin somewhere between 60-75 degrees Fahrenheit and to give the seedlings enough sunlight to thrive. My south-facing porch seems to be working so far.

I bought a $3 thermostat to keep inside the bin. That helps me track the temperature. Sometimes, despite the 30 degree (or below) temperatures outside, the inside of the bin reaches 85-100 degrees. When this happens, I just prop the cover open to let things cool down a bit.

As soon as the sun starts going fading, the temperature inside the (uninsulated) bin drops quickly. I've just been bringing the bin inside for now. Hopefully, in a week or two, I'll be able to leave the bin outside even at night.

After a week, the kale, shallots, and basil have decided to show themselves. I'm still waiting for the peppers and parsley. Still a long way to go before these babies can be planted, but I'll keep you posted!