Leucanthemum seed requires light for germination so should not be covered; rather just lightly press them into the soil and keep consistently moist until germination takes place. Leucanthemum generally will not germinate with soil temperatures above 65°F, so sow seeds early in the spring or late in the fall. Cooler nighttime temperatures, down to 50°F, will yield the very best results. These hybrids will not readily self-sow, but will spread through underground rhizomes, though not aggressively so. Plants can be divided in order to keep them in check, if "in-check" is what you want, and dividing every 2 to 4 years will keep them vigorous and healthy for years to come.