Primroses (Primulas) bloom in early spring or late winter. Their sweet flowers last for a few weeks indoors, and after they fade, most gardeners toss them in the compost bin. The Victorians loved primroses, growing the plants in greenhouses and conservatories. They've never really gone out of favor, although it’s not easy to coax them back into bloom. For best results, keep their soil slightly moist, grow them in a cool room, and add humidity to the air by sitting them atop some gravel in a tray filled with a little water. To stimulate more blooms, move your primrose outside when the weather is reliably warm. Bring it back indoors before frost, let it go dormant for a month or two and cross your fingers--or just buy new plants to enjoy. ‘Sweet 16’ is a large-flowered variety that blooms in white and shades of pink.