Cold frame conundrum

I have four cold frames that I made using plastic storage bins and two more that use glass with the thermal mass of bricks and stone. These are experimental and so far I’m seeing some clear differences in the results.

The seeds started in the thermal mass cold frames are thriving and growing much more quickly than the others. While not the exact same varieties, there are tomatoes and peppers started in both the plastic frames and the glass-brick frames.

There is one cold frame in particular (Cold Frame 4) where the seeds are ESPECIALLY slow coming up. I have only spotted one seedling in here so far:

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Cold Frame 4

Compare with Cold Frame 3, started on the same day:

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Cold Frame 3

And the big difference is with Cold Frames 5 & 6 which have the advantage of thermal mass keeping them warm at night. These were started a couple of weeks AFTER Cold Frame 4 but are growing much faster:

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Cold Frame 5

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Cold Frame 6

I have a couple of ideas about why the seeds in Cold Frame 4 aren’t coming up, or aren’t coming up as fast as all of the others.

The thermal mass surrounding Cold Frame 5 and 6 are certainly helping keep the seeds and seedlings in there warmer at night. In the desert environment here it gets a lot colder at night than it is during the day. (Why? Humidity in the air keeps the temperature more stable. You’re welcome.)

But the other  plastic cold frames are also doing better than poor Cold Frame 4, which is the lower container below:

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I’m guessing that perhaps the height on the other bins is somehow allowing for more warm air to accumulate, keeping those seedlings warmer at night too.

Or, perhaps when the plastic cold frames were next to the house #4 took on too much water one night and washed all the seeds out of the pots. It’s possible!

In any case, it’s a good learning experience. Next time I will go with thermal mass all the way. And perhaps for the time being I’ll go out and pile up some bricks next to Cold Frame 4 and see if that helps.

This episode of geeking out in the garden has come to a close! More garden geekery next time!

New cold frame

Me and my sweetie went a little crazy ordering seeds a couple of weeks ago. When we combined households last year our seed collections expanded dramatically! I added a lot of perennials, herbs and flowers to the mix, he brought a ton of tomatoes, peppers and squash. But somehow, it seemed we still needed more seeds.

And so now we need a new cold frame! My four DIY jobbies aren’t quite enough. After starting all those seeds, I still have 28 additional seed packs to start. And so, honey bunny and I wandered out into the yard looking at options for an additional cold frame system. We had several panes of glass, a bunch of big rocks and some bricks. Drawing inspiration from an article in Mother Earth News on Chinese Greenhouses, we decided to use the thermal mass from the rocks and bricks to form 3 sides of the cold frame. They should hold heat from our sunny days to keep the starts warm during cold nights. The top and front will be glass.

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We, or should I say, he, got a good start on this over the weekend and both of us are psyched. The finished project will be a combo cold frame and garden bed which we’ll use to plant a few things like lettuce that would be useful a bit closer to the house. Which is an important principle of permaculture – keep the things you need to access more often closer to the house. The cold frame and raised bed will be in our zone 1, a few steps outside our front door.

Cheerio and until next time!