Robust and compact, Heuchera 'Citronelle' features showy, citron yellow leaves adorned with silver undersides that retain their luminous color throughout the growing season. If planted in a shady area, the foliage becomes more chartreuse. In mid-summer, panicles of small, bell-shaped, creamy flowers bloom on slender stems rising up to 14 in. (35 cm), just above the semi-evergreen foliage. A terrific choice for adding a touch of color in the rock garden, perennial border, along paths or in…