Shastas grow best in full sun; be sure that your plants get at least 5 or 6 hours of full sun each day (in hot climates, part sun in afternoon is helpful). Soil should be well-drained and moist but not waterlogged.
Also, check that the plants are not receiving too much nitrogen, which promotes leaf growth over flowers.
Some gardeners pinch back stems of taller varieties in early spring, when growth gets to about 6 inches long but before buds develop, to encourage bushiness; this may delay flowering, so you might hold off on this technique until the flowering issue is resolved. If your plants do flower, remove the spent blossoms to encourage more to develop. In cold climates, prune the plant back to 1 or 3 inches tall in fall, after flowering.
Shastas grow best in full sun; be sure that your plants get at least 5 or 6 hours of full sun each day (in hot climates, part sun in afternoon is helpful). Soil should be well-drained and moist but not waterlogged.
Also, check that the plants are not receiving too much nitrogen, which promotes leaf growth over flowers.
Some gardeners pinch back stems of taller varieties in early spring, when growth gets to about 6 inches long but before buds develop, to encourage bushiness; this may delay flowering, so you might hold off on this technique until the flowering issue is resolved. If your plants do flower, remove the spent blossoms to encourage more to develop. In cold climates, prune the plant back to 1 or 3 inches tall in fall, after flowering.