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Due to the multiple varieties of Sweet William and the different methods of growing them, you may hear conflicting information on when your flowers will grow and how long they will last. Biennial varieties bloom in their second year, and then die. Perennial varieties are supposed to regrow flowers year after year, but Sweet William perennials usually take two years to bloom and often die before they bloom a second time. Correct care of Sweet William perennials increases the chance of reseeding, as described in the section on caring for Sweet William. If you want your Sweet William to flower reliably within a year, acquire seedlings or adult plants in fall or spring. Confirm with the previous owner that the plant will bloom this year before you take it home, since some seedlings may not flower until their second year. Seeds that claim to be annuals (flowering and dying within one year) may or may not live up to the promise, depending on the variety and how it reacts to your local climate. Sweet William seeds are tough enough to survive most winters, and can be planted in fall or late spring to bloom 12 to 18 months later. If the plants have already started growing, or if you are concerned about a harsh winter, you may keep the plants in indoor pots, then transplant them outdoors in early spring. Once the seedlings are six to eight weeks old, they will transplant easily, with low risk of causing damage. Sweet Williams grow fastest in full sun, but are best suited for cool climates. Ideally, they should receive four to five hours of direct sunlight a day, but planting them in light shade is a wise option if you live in a hot climate (USDA zone 8 and above). Sweet William prefers loose, rich soil that is well draining. Water should drain quickly through the soil, and never pool on top of compact, hard soil. Optionally, you may churn up the existing soil and supplement it with potting soil to provide more nutrients. While you do not need to test the pH of your soil to successfully grow Sweet William, you may adjust the pH to slightly alkaline (approximately 6.75) if you already have a pH garden kit. Garden soil pH kits are available at garden supply stores or online. Again, this is not a mandatory tool for growing Sweet William, which are fairly adaptable when it comes to soil pH. Plant Sweet William in winter (hot climates only), spring, or summer (cool climates only). Place them on the surface and lightly cover them with 1/8 inch (0.6 cm) of soil, or dig a trench to this depth and refill after planting the seeds. Space the seeds 6 inches (15 cm) apart in ideal circumstances to reduce the chance of rot and disease transmission. If you do not have room to give them this much space, you may bunch them closer together, but take special care not to overwater in this case. If you are transplanting seedlings, simply transfer the soil around the roots into a hole twice as wide as the soil ball, then refill. Take care not to bury any part of the seedling's stem; the plant should be buried to the same level it was before. Sweet William seeds and seedlings benefit from an immediate watering after transplanting, but take care not to soak them with more water than can drain from the soil. Transplanted seedlings should be kept in moist but not soggy soil for a few days. Once they are established and recover from any withering that may occur, care for them as described in the care section.
Find out when your Sweet William will bloom. Acquire a growing plant if you want to see flowers within a year. Decide when to plant. Find an area with good sunlight but cool temperature. Check your soil. Sow your seeds. Water after planting.