Monday, October 29, 2018

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

Characteristics Supports Must Have:

  • Sun proof (no PVC)
  • Lightweight
  • Inexpensive
  • Easy to acquire
  • Easy to shape (no metal conduit)
  • Doesn't snag the frost cover cloth (no rebar)
  • Makes an arc high enough to let lettuce grow under it (2 feet)

Calculating the Support Length

This handy "arc calculator" told me that with my bed width of 6 feet and arc height of 2 feet, I needed about an 8-foot support.  To use the calculator, enter the width of your planting bed as "Width of Arc" and the height you need as "Height of Arc".  The "Length of Arc" is how long your support needs to be, and then add whatever length you will lose anchoring it in the soil.

Picking a Material

The requirements suggest that wire is the best material. I could have cut lengths from heavy wire but they need lateral support to keep them from flopping sideways.  I could have used welded wire cattle panels or remesh but they are big and unwieldy.

That led me to the concrete block and stucco supply aisle for a product called "ladder mesh" (also known as masonry ladder, or ladder wire).  It is used to reinforce concrete block walls.  The 2-wire mesh is widely available, comes in 10-foot lengths, and costs about $4. The ladders are - confusingly - named by the size of the concrete block they are used with. So, "8-inch" ladders are really only 6 inches wide.

Stabbed into the dirt, the ladder is stabilized by the legs and makes nice arches. Ideally, I would have 10-foot frost cover, but it is only 6 feet wide and I need 2 pieces.

Wire Ladder Arches Installed

For lateral stability, and to better support the frost cover if we get snow, I added one ladder across the top of the arches.  If you are in an area with heavy snow fall, place the arches closer together and use more ladders across the arches. 

Top Reinforcement: Another Ladder
The bok choi seedlings I started in soil blocks a couple of weeks ago are already planted out and growing.  I topped off the raised bed with several inches of compost and thoroughly watered it before setting out the seedlings.
Bok Choi Seedlings

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