RT Journal Article SR Electronic T1 Root Hardiness of Green Ash Seedlings From Different Provenances JF Arboriculture & Urban Forestry (AUF) JO JOA FD International Society of Arboriculture SP 276 OP 279 DO 10.48044/jauf.1979.067 VO 5 IS 12 A1 Frank S. Santamour, Jr. YR 1979 UL http://auf.isa-arbor.com/content/5/12/276.abstract AB Container-grown seedlings of green ash from different provenances were subjected to temperatures of −9°C and −15°C for 1 week. Roots of seedlings from areas where the average January temperature was above freezing were completely killed by both treatments and no shoot growth was produced. Root tips and young roots of seedlings from areas with average January temperatures between 0.1 °C and 24.2°C were killed by the −9°C treatment but new roots developed and stem growth, although retarded, was resumed. The −15 ° C treatment killed all roots of all seedlings, but a few plants from the coldest origin initiated new roots from the root collar zone and the plants resumed shoot growth from lateral buds. It is recommended that landscape trees planted in above-ground containers in northern areas be selected from the coldest origins or, when cultivars of unknown geographic origin are so used, that they be budded or grafted on potentially cold-hardy rootstocks.