Using Cold Frames for Early Spring Protection of Carnivorous Plants

A grower 90 miles north of NYC (Zone 5A) asks when to uncover plants in a PVC-and-frosted-plastic cold frame while nights still dip into the teens (°F).

Wait for Consistent Warmth

If nights are still in the teens, keep plants covered. Once emerging from dormancy, most temperate carnivorous plants tolerate only the upper 20s (°F). The most vulnerable early emergers are Drosera tracyi, D. filiformis “Florida Giant,” and sometimes Venus flytraps.

Ventilate on Sunny Days

On bright days, open the cold frame widely to prevent overheating, which forces premature emergence and subsequent damage when cold returns. Let plants wake at nature’s pace. We use clear plastic (Visqueen) mainly as a rain shield; it slightly accelerates growth, but we roll up sides whenever sun appears.