Using Well Water and Overwintering Carnivorous Plants in a Greenhouse

Question: I'm a newbie who bought your e-book and a lot of plants. I'm shocked at the video showing plants outside in the snow! My questions: Can I use well water? And which plants can be kept in an unheated 8' x 6' x 7' greenhouse (green cover, wire shelves, wood floor) during snowy, cold winters with ice storms in Missouri? I know I'll keep my Cephalotus and Cobra Lilies inside, but what about Nepenthes? Should they all come inside?

Answer

Hi Judy,

That type of greenhouse functions as a simple cold frame. It's suitable for Sarracenia and Venus flytraps when temperatures dip into the 20s or upper teens for short periods. However, when winter brings extended periods in the single digits (like I experienced in St. Louis), you'll need extra protection. For a small collection, an ice chest works well during the coldest snaps. Alternatively, a small space heater can keep the greenhouse in the 20s and 30s, and adding an extra layer of plastic outside improves insulation.

Here in Oregon, winters are mostly rainy with temperatures in the 30s and 40s, plus overnight freezes during clear spells. We occasionally get snow and teens temperatures, but these cold snaps rarely last more than 4–5 days. Your cold snaps are much longer, so potted plants need more protection.

All your Nepenthes should come inside well before the first frost.

Regarding well water: most of Missouri sits on limestone bedrock, making the water very hard (high in calcium). It's unsuitable for regular use—only okay in an occasional pinch. Use rainwater, distilled water, or reverse osmosis filtered water. Other filters or softeners don't remove minerals.

Good Growing!
Jeff Dallas
Sarracenia Northwest
www.cobraplant.com