98-112 days. Silver Shield plectranthus seeds are a simple and exotic Australian grow ideal for many hot and humid gardens. Silver Shield seeds promise 24-36" tall mounds of silvery green leaves with bluish white floret spikes perfect for highlighting walkways, borders, fences, or patios. Silver Shield plectranthus is native to eastern Australia's sweltering and rugged rainforests and will thrive all summer in similar climates. Silver Shield seeds mix well with lavenders and other soft blooms that last well into the season. 100 seeds.