Frost Cover Failure: Did They Live?

It's Flat and It's Freezing. Are they Frozen?

First there was this. Snow I should have prepared for, but didn't, flattened my frost cover. Then there was a spell of unusually cold weather for here, with the days at or barely above freezing and the nights well below freezing.

Left: Before
Right: After

I abandoned the leafy greens to their fate in the frozen wasteland and hoped the snow would be enough insulation to keep them from dying. I sat inside, sipping hot tea and snuggled with my cats, and waited.

Finally, after more than a week, the daytime weather warmed up a bit. The arches began to spring back up as the snow melted. It was looking like a snow snake's spine and I could see greens, although I couldn't tell if they were frozen dead greens or live greens.

Starting to Thaw, 10 Days Later

To see the thrilling finale of this cliffhanger ...
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Snow Is Heavy, Frost Shelter is Flat!

Engineering Failure: Will the Plants Survive?

We had several inches of snow overnight in late December. Light fluffy powder snow that squashed my frost cover!  More snow and sub-freezing daytime temperatures are forecast so I am going to wait until that is over before I dig down to see if the plants are alive.

It's flat.

 It's clear that I need some vertical support for the arches. I wasn't even thinking of possible snow weight, because high winds were the immediate threat. 

This on-line snow load calculator says there were 50 to 60 pounds of snow being held up by slender wires and some frost cloth.

Will the Plants Survive?

I hope so. I'll post when I find out. Read more!

How Do Frost Cloth Covers Trap Heat?

Garden Science

The leafy greens in the raised bed are thriving under the frost cloth tent. They've been planted out about a month and I am harvesting leaves. Harvest one leaf per plant and I can decorate a sandwich. Salads will come later.

One Month's Growth of Bok Choi

I always assumed that frost cloth worked by trapping heat under it, with stored heat from the ground keeping the air temperature above freezing. But I got curious and when I had the plants uncovered to water and weed them, I put a wireless remote thermometer under the tent.

Temperature? I recorded the temperature under the cloth and from an online personal weather station a block away periodically from 2PM until about 1PM the next day.
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Frost Cover Support: Rev 3.0 "Ladder Mesh"

The best version yet!

My first version of a frost cover support for winter vegetables was cobbled together in a hurry from available material with a cold front roaring down from Canada.  It was fast and effective but not convenient. The so-called "improved version" was not much better. This winter I took the time to think through the requirements for the supports before the freezes get here. Planning!  It works!

Improved Frost Cloth Support

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Improved Frost Cover Support

The frost cloth was working, but rain made it sag and I was afraid the weight of the wet cloth would rip itself.  I added support lines between stakes to support the cloth in more places. It worked well after a moderate rain and a light snowstorm.

Support lines shown in yellow

It's easier to put on and off, and the cloth doesn't snag around the support posts.

The lines use clove hitches around the base of the mushroom cap on each support - it's an easy knot to make and unmake, easy to adjust in the middle of the line, and one of the few that can be made in the middle of a line without untying one end.

Supports with the added guy lines (orange garden twine)

 Possible Variations and Improvements

I don't have time to try these, but they would work.

• Alternate supports ... use PVC pipe with end caps.  PVC pipe can be cut at home, is not as rough and is less likely to snag the frost cloth than rebar.
• For a removable but convenient support system, pound in pipe big enough to hold the supports so you can drop them in quickly. Plug the pipe holes with something between uses to keep dirt, dead leaves, and critters out.

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The problem with USDA Plant Hardiness Zones

Any system that puts Phoenix, Arizona and Orlando, Florida together has a serious flaw.  But they are both USDA Hardiness Zone 10.

"USDA Plant Hardiness Zone Map is the standard by which gardeners and growers can determine which plants are most likely to thrive at a location. The map is based on the average annual minimum winter temperature, divided into 10-degree F zones."

What it really means:  The USDA Plant Hardiness Zone Map helps determine which plants are unlikely to die of cold weather at a location, not thrive.   There are many other reasons your location will kill unsuitable plants.  The picture below shows part of the problem.

Both city parks are in USDA Hardiness Zone 10

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No-Tool Frost Cover Supports for Tender Landscape Plants

We joke that the the classiest house in the Phoenix area looks like a low-class Victorian washerwoman's house when a freeze is coming, because Phoenicians grab anything at hand to cover plants (Check the images. The Superman sheets are fab!) when one of the rare freezes is coming.  King size sheets and muslin curtains are popular, propped up with anything from saw horses to dining chairs to keep the covers off the plants.  Plastic drop cloths are popular, but you can cook your plants under the plastic if you forget to take it off.

If you have a bit more time to prepare, or live where frost protection is needed several times a winter, try this inexpensive solution that won't leave you sitting on the floor with no sheets on the bed. It looks like an old-fashioned circus tent.

Frost Cloth and Rebar Tent

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