ISHS Acta Horticulturae 56: 105-114. Symposium on Juvenility in Woody Perennials
Accelerating Maturity in Picea Seedlings
E. Young, James W. Hanover

When several species and interspecific hybrids of spruce (Picea) were grown from seed under a 24-hour photoperiod with optimal temperature, moisture, and nutrient levels they did not enter dormancy, but exhibited a continuous and vigorous free growth. This "accelerated-optimal-growth" treatment shortened the juvenile period and promoted precocious flowering after out-planting. The seedlings also demonstrated a more rapid or mature growth rate after outplanting at an earlier age than naturally-grown spruce. Picea pungens seedlings grown initially under natural conditions did not respond to the extended photoperiod treatment after reaching three or more years of age.

Continuous Lighting