Gilbert Fritz

I've discussed in past posts that there is a lot of vacant land near Denver that could be used for urban farms, but most of it does not have water access and getting water installed is prohibitively expensive. With only 15 inches of rain a year, there is a very limited range of vegetable crops that can be grown without irrigation.

What if a farm was laid out in alternate rows on contour 8 feet wide, and every other row was a plastic covered low tunnel. However, the plants would not be growing in the low tunnels, but in the open rows. On the long sides of the tunnels the plastic would be buried in the bottom of shallow mulched trenches.

This would give the uncovered plots the equivalent of 30 inches of rainfall. Furthermore, light rains that would have merely evaporated off open ground would be concentrated into the trenches and sink into the soil, thus boosting efficiency of water usage.

Would this set-up work to grow standard vegetable crops? (Combined, of course, with mulching, varietal choice, etc.)

I know lots of people say pill bugs are harmless . . . but I've found them to be a problem. It seems that if plants are stressed by harsh conditions, they will happily eat them. I've lost lots and lots of plants, particularly beans, to pill bugs, particularly in growing seasons with harsh weather. Pill bugs really like mulch. It may be a good idea to pull mulch away from tender young plants. Also, I've heard that spreading pulled up weeds around the garden might help; it gives the pill bugs some other stressed greenery to munch on. But I've never tried it.

It has got some dramatic scenery, any way!

Would heavy rain/ melting snow on nearby peaks lead to flash flooding along that torrent? Has it happened before?

Any thoughts?

There are relatively new herbicides out there based on iron chelate. I'd like to get some thoughts on them. As far as I can tell, they contain iron in an organic, easily absorbed form, thus giving sprayed plants a fatal, systemic overdose.

What would the fate of this herbicide be in the soil? I assume that it would quickly become part of the 100,000 pounds of unavailable iron already in the average soil, particularly if the soil is alkaline?

What do you all think about the safety/ permie compatibility of this herbicide? It sounds like it would work better than the organic acetic acid herbicides available, since it is systemic. What would be the downsides?

I'm interested in this because to my mind one of the big problems in permaculture is removing spreading perennial weeds from established landscapes. Once a complicated landscape is in place, sheet mulches are not an option and hoeing/ hand pulling may be ineffective, particularly if the weeds are emerging from rock or masonry elements in the landscape, or near woody plants.

Mike: thanks for the advice. I'd much rather use 100 feet of PEX than 30 feet of copper.

Do you think the baseboard radiator in a tube idea would transfer the heat well? I was wondering if the air would just flow around and past the whole assembly instead of between the fins, thus minimizing heat transfer. But it is something to think about.

Unlike in the video at the top of the thread, I'm planning to have a heat exchange coil in the tank so that I can run a propylene glycol mixture through the radiator. I'd like to use PEX instead of copper. How long of a PEX tube would I need to get the maximum heat exchange?

Or would this be just too hard on the pump? Should I just run the tank water through? Buying enough propylene glycol to fill the tank is prohibitively expensive.

Thanks for all the discussion!

I really like the idea of ductwork; I'd been trying to think up ways to get the fan and radiator suspended up near the peak, and how that would work with headroom, vents, etc. Ducting the air to a fan at ground level would create much better airflow.

I may install one with a temporary tank to get the sizing worked out before finalizing anything.

I have (finally!) got my high tunnel greenhouse built and covered. It is a plastic, uninsulated structure, partially sunk in the earth, 16 feet long and 10 feet wide, with the aboveground height being 5 feet. I don't want to heat it through the winter, but instead want it to moderate the large daily and seasonal temperature fluctuations in Colorado. To this end, a scrap radiator connected to a tank of water sounds like a good idea: see here: https://northernhomestead.com/car-radiator-for-heating-and-cooling-a-greenhouse/

The big difference is that I plan to use water in the tank, but Polyethylene glycol antifreeze in the radiator, circulated through a coil of pex pipe in the tank.

I realize that you can't give me exact answers, but I'd like to get a ballpark idea on the following:

How big should the tank be to keep the greenhouse at 25 F when the outside temp is at 0 F? 150 cubic feet? 50 cubic feet? 300 cubic feet?

No, I'm out. Sorry about that.