| There are approximately 40-60 species of Grindelia native to temperate, mostly arid and semiarid regions of North and South America. Grindelia species include annuals, biennials, herbaceous perennials, and shrubs. Some of the more common names include gum weed, tarweed and sticky-heads. All plants are cultivated for their attractive ray-like flowers; some are grown commercially for their resin content. Seeds require light to germinate and a pre-soak prior to sowing. Optimum germination occurs at temperatures of 10-20C. Pretreat by soaking in water, then sow on the surface of moistened seed starting mix. Seeds should germinate in 8-14 days. |
