I'm new to this group, so I thought I'd get my feet wet by making an observation and posing a question. All of the Japanese maples in our area (Cedarburg, Wisconsin) have retained their leaves this winter. However, 'Arctic Jade,' a hybrid of Acer palmatum, dropped its leaves. Has anyone seen this before? Any problems once spring and new leaves arrive? I only have one pure Japanese Maple ('Skeeter's Broom') because of hardiness issues here. Other than 'Bloodgood,' from which 'Skeeter's Broom' originated, are there other cultivars with exceptional hardiness? I am successfully growing A. griseum and its hybrids 'Gingerbread' and 'Purple Haze,' 'Arctic Jade,' 'Northern Glow,' A. shirasawanum 'Autumn Moon' and 'Mr. Sun,' A. spicatum, A. triflorum, and A. tegmentosum 'Joe Witt' and 'White Tigress.'