Again this spring, two twenty degree nights slightly damaged newly emerging leaves of ‘Twombly’s Red Sentinel’ Japanese maple (Acer palmatum ‘Twombly’s Red Sentinel’, below). Happily, other maples show minimal or no damage, and all (including Twombly’s) will be fine with no evidence of damage by late spring. ‘Twombly’s’ suffered similar browned leaves a year ago,…