Straw bale insulation around raised beds

Stacking straw bales around the exterior of raised beds in late fall creates additional insulation that moderates temperature swings and protects root zones from deep freezes. Straw is an excellent insulator (used in building construction for centuries) with an R-value of approximately 1.5 per inch. A standard straw bale (14x18x36 inches) placed against a bed wall adds roughly R-20 to R-27 of insulation. Position bales tightly against all four sides of the bed, then cover the bed with a cold frame lid or row cover for a complete insulation envelope. The bales also block cold wind from desiccating plants. This technique can extend the growing season by 3-4 additional weeks in fall and protect overwintering crops like garlic, strawberries, and perennial herbs. Straw bales cost $5-10 each; a standard 4x8 bed requires 6-8 bales. In spring, the bales can be broken apart and used as mulch on the bed, so nothing is wasted. Use straw (hollow stems), not hay (contains seeds that will sprout as weeds). This method works best in zones 4-7 where winter temperatures regularly drop below 20 degrees F.