HOW TO GROW SWEET WILLIAM (DIANTHUS) FROM SEED How to Plant Herald of Spring Mix Sweet William Seeds WHEN TO PLANT SWEET WILLIAM SEEDS Sweet Williams are biennials and can be planted in late Spring after danger of frost has passed or Fall. You will get blooms during the second year after planting. WHERE TO PLANT SWEET WILLIAM SEEDS Sweet Williams do best in 4-5 hours of full sun each day. They can be directly sown or started indoors. Plant in well-draining soil that is slightly alkaline (pH 6.75). HOW TO GROW SWEET WILLIAM SEEDS Place seeds 1/8" under soil ideally 6" apart. You can plant them closer together so long as the seeds are not overwatered. If transplanting, make sure the hole is twice as big for the root system. Make sure that only the roots are covered with the new soil. If started indoors, they can be easily transplanted after 6 weeks growth. HOW TO CARE FOR SWEET WILLIAM They do not need a lot of water- except in hot months. Soaker hoses are best. Do not over water as this can cause yellow foliage.