Kumson Forsythia Forsythia intermedia 'Kumson' Description Blooms yellow flowers. White foliage with dark green speckles.Bloom Period: Early SpringGrowth Habit: Upright and roundMature Height: 4' to 5' (122 cm to 152 cm)Mature Spread: 4' to 6' (122 cm to 183 cm)Growth Rate: Moderate More Details Sun Exposure: Full sun to partial shadeCold Hardiness Zone: 5Cut flowerLandscape Use: Garden accent