Myosotis sylvatica, or forget-me-not flowers, are perennial, and rebloom year after year on the same root system. The plants grow less than 1 foot tall, with small blue flowers. The flowers bloom in early spring, and under normal circumstances and healthy growing conditions the blooms will appear for two to three months out of the year.
Forget-me-nots can be grown outdoors in USDA Plant Hardiness Zones 3 through 9. The flowers prefer moist soil. Forget-me-nots will grow and flower in full sunlight or full shade. They grow without cultivation and are very low-maintenance plants. The flowers reseed regularly, and as long as this cycle remains undisturbed they will return to the garden every spring.
Plant forget-me-not seeds directly in the garden after removing the site of all weeds. Water the soil the day before so it will be moist enough to receive seeds. Plant seeds from May to September, burying them just under the surface of the soil. Newly planted forget-me-not will not bloom until the second spring, but after they do bloom, they will do so annually.
Forget-me-nots are hardy to minus 30 degrees F, and do not survive well in extreme heat. When planted correctly in their ideal habitat, the blue flowers will bloom continuously in the spring for two to three months, from April to June. Once the heat of summer sets in, remaining flowers will wilt and new buds will fail to form.
Thin out forget-me-nots if they become overcrowded; the flowers need air circulation to stay healthy. In dry, hot conditions, the flowers may not bloom when expected or for as long as expected. Keep forget-me-not soil moist, and give them extra water when weather is hot. As long as flowers remain healthy, blooms will appear on schedule.