Using straw or alfalfa bales to build coldframe!

I bought a large bale of alfalfa today for $9.00. I will use it this winter to mix into my beds and add to my compost pile.

I was wondering how well straw or alfalfa bales laid on black plastic with two on the sides and one bale on each end would work for a cold frame. Clear plastic could be laid over the top held down by boards or rocks. I think the bales would provide adequate insulation to protect the plants from cold nights but not from an extended cold spell. You could stick a shop light on an extension cord under the plastic cover if you feel added heat is needed.

If you want it at an angle to face the sun, you could lay the bales on a sheet of plywood and raise and support the sheet of plywood on one side.

The bales of straw could be used as mulch after the plants are growing and simply replace them each year for the cold frame. The bales would be cheaper than buying lumber to build a cold frame.

I've never done it, but I'm curious if it would work.

Ted

[RinTinTin]

Hay/straw bales are great insulators...much better than 1"x or 2"x lumber. Poultrymen often bank bales around their hen houses for winter protection, then use them in spring/summer/autumn for floor litter, which later gets used as N rich compost. Three distinct uses from a "throw away" item.

[tjcnok]

We have done this ourselves with some good results. Only drawback we experianced is limited amount of sunlight directly over head to warm the plants as the sun just doesn't get high enough in the sky in winter. I think using the clean wheat straw for mulch after the garden got started in spring contributed more.

[ddsack]

Perhaps digging a six inch to one foot deep trench to set the hay bales in would lower the sides of the bales and allow more sun in?

Or use hay bales on three sides, and a shorter styrofoam panel on the south side, or leave the south side open, maybe putting in some chicken wire or a bar across the hay bales, something to keep the plastic from sinking too close to the plants on that side. Then use loose sections of hay over the plastic flap to insulate that side at night.