When it comes to hydrangeas, I’m certifiably loony. Or, at least, I used to be. The source of my obsession was a variegated hydrangea. I bought it in full flower, and the azure, lacecap blooms were simply stunning against the backdrop of broad, spade-shaped leaves edged with creamy white. Then winter hit and it died to the ground. New shoots burst forth in spring, adorned with luscious foliage, but no blooms appeared. Ditto the next spring. And the next. Apparently the plant was root-hardy here, but its stems and flower buds—which form on year-old growth—were not. In my USDA Hardiness Zone 6 Connecticut garden, Old Man Winter prevailed.
But it got me thinking that if I kept my variegated hydrangea (Hydrangea macrophylla‘Tricolor’) warmer, its stems and buds might survive. So I decided to cover the plant in winter. I bought one of those homely-looking Styrofoam cones sold to protect tea roses in winter, capped the hydrangea, and covered that with a layer of shredded leaf mulch and pine boughs. Then I waited until the next summer when—lo and behold—the hydrangea flowered.
Emboldened by success, I started experimenting with other marginally hardy plants, using everything from small glass domes to homemade, doghouse-sized plastic greenhouses. I soon realized winter cover-ups could provide an extra zone or more of warmth. I’ve used these devices to help late-season transplants get established, protect recently transplanted evergreens, and coddle a few choice perennials that would otherwise never survive winters in my garden. There’s nothing complicated about it. I rarely spend more than 15 minutes prepping a plant for winter, and unveiling it for spring takes even less time. My methods aren’t foolproof. There’s still a casualty or two every season. But even with occasional losses, my efforts are repaid several times over each year.