Brunnera macrophylla ‘Jack Frost’

Brunnera macrophylla 'Jack Frost' is the Perennial Plant Association's 2012 Perennial Plant of the Year. 'Jack Frost' is a sport of Brunnera macrophylla 'Langtrees' and was discovered in the greenhouses at Walters Gardens in Zeeland, Mich. It was introduced commercially in 2000.

'Jack Frost' produces distinctive silvery leaves with green primary and secondary veins and a thin green rim on the leaf edges. From mid- to late spring, plants produce clusters of baby blue flowers several inches above the foliage.

'Jack Frost' grows 12-15 inches tall and wide. It tolerates heat better than other Brunnera varieties. Plants are hardy to USDA Hardiness Zones 3-8.
 

• Plugs should be planted into finished containers filled with a growing medium that has a pH of 5.8-6.3 and electrical conductivity of 2.0-3.0 (pour-thru method).
   
• When rooting plants in spring, maintain a temperature of 65°F, then drop to 55-65°F to finish. When overwintering, do not let the soil drop below 35°F.
   
• Plants should be grown under 55 percent shade. High light intensities can cause leaf scorch.
   
• Plants have a fibrous root system so do not overwater or allow the growing medium to dry out.
   
• Fertilize plugs using a constant liquid feed of 100 parts per million nitrogen. For finished containers increase the rate to 125-150 ppm nitrogen. No plant growth regulators are needed.
   
• Production time for 20-cell plugs is six to eight weeks when finished in 1-gallon containers or 10 weeks in 2 gallons. The 72-cell plugs should be received in the fall to finish in 1-gallon containers for spring sales.