O Yashima Flowering Quince. This Japanese cultivar of our Flowering Quince is best known for its enormous double white flowers which bloom here in February and March, but further north will flower somewhat later. A unique aspect of this cultivar is that the flowers will open as a soft green color which then slowly turns white. It is quite vigorous and will reach about 6' with time with an equal spread. As with all quince, they flower best in full sun to part shade with well drained soil. An occasional shot of lime and fertilizer is about all they will ask of you.