Saturday, January 7, 2017

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
Buy real frost cover fabric, some rebar stakes and some rebar caps. The rebar supports can be left between frost episodes, the cloth can be rolled up to let the plants get sun, or left in place.  Unlike plastic, the plants won't overheat under the frost cloth.   Plastic caps on the rebar protect the frost cloth from snagging and the gardener from scratches. 

  • A pack of a dozen or more of rebar caps (also called "mushroom caps")
    Buy the inexpensive ones, not the OSHA approved ones.
  • Suitable lengths of 3/8" or 1/2" rebar.
    The rebar should be 18-24 inches longer than the plants are tall (6 to 12 inches clearance, 1 foot in the ground.  You can usually find them pre-cut in a building supply store, or have them cut for you.
  • Frost cloth, large enough to cover your plants. 
    The common sizes are 84 inches and 10 feet for rolls.  Measure over the top of the foliage and buy the size you need.  You can overlap the frost cloth if you need to, as long as you clip it to keep the coverage complete.

Pound a line of supports down the middle of the area, about 3 feet apart, and along the edge of the planting.  The supports should be 6 inches or more above the foliage. You'll have to use your imagination, because this is not tropical shrubbery, it's my vegetable bed.

Stick a plastic cap firmly onto each support.
Rebar Supports with Caps
Drape the frost cloth over the supports, completely covering the plants to ground level.  Make sure you have several inches on each side to anchor the cloth, and no gaps to let wind or cold air in.

Variation: Staple a sleeve or hem in one or both ends, or tape the fabric, insert pvc pipe and roll it up to store, unroll to apply over the supports, leaving the pipes in the hems as anchors.  This is more manageable than a strip of cloth for the wider widths, but it might need 2 people to unroll it.


My original plan was to tie the frost cloth around each mushroom in the center and the edge to hold it in place, but the cloth started ripping at the ties.  Then I resorted to bricks around the edge, which you see here. Smooth rocks, jugs of water, even canned food will work.

The tent is surprisingly wind resistant. We've had long periods of 20MPH sustained winds and days with gusts over 40MPH and it's still there. It flutters, but doesn't get airborne. The only rips are where the stress from the ties ripped the cloth.

This style does not work as well for winter vegetable beds as a cover supported on hoops would because it's not as easy to work with the plants under the tent, but if you won't be weeding or harvesting very often, it's better than nothing.

My recently set out leafy green vegetables are surviving, even though the top inch or two of the bed freezes solid, the bits of coarse compost are frosted, and the leaves are rimmed with frost every morning.  By mid-morning the frost is gone and they look normal. 

Frost on Lettuce in Early Morning

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