On the subject of winter interest, one unusual conifer demands attention this time of year. During warmer months, the upright Japanese plum yew selection Cephalotaxus harringtoniana ‘Korean Gold’ leaves observers wondering why a dark green plant has such a name. Only after a few late fall cold snaps will the show really start, when the outer foliage is gilded with bright yellow highlights and contrasts sharply with the dark green inner needles. This winter coloration is produced through an interesting process called “photoinhibition”. During winter when the plants are dormant and physiological functions are slowed down, they undergo a temporary change that allows them to deal with excessive sunlight that would normally be utilized for photosynthesis during the warmer months of the year. This change of color is not to be confused with fall color on deciduous trees, as these colored needles will not fall off.  On the subject of winter interest, one unusual conifer demands attention this time of year. During warmer months, the upright Japanese plum yew selection Cephalotaxus harringtoniana ‘Korean Gold’ leaves observers wondering why a dark green plant has such a name. Korean-GoldOnly after a few late fall cold snaps will the show really start, when the outer foliage is gilded with bright yellow highlights and contrasts sharply with the dark green inner needles. This winter coloration is produced through an interesting process called “photoinhibition”. During winter when the plants are dormant and physiological functions are slowed down, they undergo a temporary change that allows them to deal with excessive sunlight that would normally be utilized for photosynthesis during the warmer months of the year. This change of color is not to be confused with fall color on deciduous trees, as these colored needles will not fall off.

Many conifers will show photoinhibition to a slight degree if conditions are consistently cold, appearing in winter as light green to slightly golden, or in some specie bronze, brown or reddish purple. Even loblolly pines will have a slight, barely noticeable light green to gold hue after some cold weather. However, certain rare individuals will display photoinhibition to an excessive degree, visually appearing a bright shocking gold, and these notable examples become popular winter garden subjects. Korean-Gold-(2)There are several cultivars of pines, hemlocks, firs and spruces that are as yellow as a school bus in winter, then revert back to normal green in summer.

Unfortunately there are few of these selections that are adaptable to southeast Texas, or they will thrive but simply don’t receive enough chilling to attain the coloration in USDA zones 8-9. Cephalotaxus harringtoniana ‘Korean Gold’ is one of the few that will develop color in winter in this area, most prominently in the inland sections away from the warming influence of the gulf. Though plum yews are most often utilized in shady garden settings, most will also happily take nearly full sun but might require a little more irrigation. In order for ‘Korean Gold’ to attain the best winter color it will require this sort of open exposed conditions. In sheltered areas it will remain plain green, no different than the regular form of upright (fastigiate) C. harringtoniana.

 

-Adam Black