| Popis: |
Five structureless overwintering systems were evaluated for temperature moderation and protection of 18 container-grown herbaceous perennials from low-temperature injury. Two light-excluding treatments; 30-cm (1-ft) of straw between two layers of 4-mil white polyethylene, and 18-cm (7-in) deep, in-ground beds protected with one layer of 4-mil white polyethylene and 30-cm (1-ft) of woodchips, provided the greatest moderation of winter low and early spring high temperatures, but also resulted in severe etiolation. A bonded white polyethylene/microfoam overwintering blanket (thermoblanket) with translucent properties provided comparable plant survival percentages despite dramatic temperature extremes recorded beneath this cover and, in late winter, created an environment conducive to moderate plant growth without formation of etiolated tissue. Additional index words. Achillea taygetea xmillefolium L. "The Beacon', Coreopsis lanceolata L. "Goldfink', Coreopsis vertidllata L. "Moonbeam' and "Zagreb', Delphinium elatum L. "Giant Pacific Hybrid', Gaillardia xgrandiflora Van Houtte. "Goblin', Geum quellyon Sweet. "Mrs. Bradshaw', Heuchera sanguinea Engehn. "Bressingham Hybrids' and "Splendens', Physostegia virginiana (L.) Benth. "Pink Bouquet' and "Summer Snow', Platycodon grandiflorus (Jacq.) A. DC. "Fuji Blue', Salvia xsuperba Stapf. "Stratford Blue', Sedum spectaUle x-telephium L. "Autumn Joy', Sedum spectabile Boreau. "Brilliant', Tanacetum coccineum WUld. "Robinson's Mix', Veronica repens Loisel., Veronica spicata L. "Icicle', etiolation, temperature monitoring, thermocouple, winter protection |
