How Long Do Dianthus Take to Flower from Seed?. 16-18°C. Alba is a white flowered variety of Thrift. Sea Thrift likes a well-drained soil in full sun. Quick Growing and Care Guide. as it can tolerate windy conditions and salty air. Thrift or Sea Pink grows in any kind of well drained soil. The best type of soil for this plant is sandy and it does not need to be overly fertile. How to Grow Thrift - Armeria. Dianthus is a genus of about 300 species of mostly low-growing plants, including annuals, biennials and perennials, that are native to Europe and Asia. Buy a cheap copy of Gardening from Seed: The Keys to Success... book . Cosmos are half-hardy annuals that grow, flower, set seed and die all in one year, but unlike hardy annuals, they can’t withstand low temperatures.. They’re quick and easy to grow from seed, flowering in as little as 12 weeks, and can be added to borders and pots for a burst of showy colour. I had the job of growing them on to become useful plants for the garden. Plant trees.