Penstemon Seeds - Palmers120 days. Growing Palmer's penstemon seeds this season is an effortless and vibrant way to splash some familiar summer color and fragrance into your home or garden. Palmer's seeds grow elegant 36 48 tall penstemons bursting with perfuming floreted snapdragon like stalks ideal for indoor planters or as an eye catching border around any flower bed. Palmer's penstemon seeds grow bold and brilliant flowers promising butterflies and important pollinators