Step 1: Timing
Direct sow repeatedly after the last frost date. Starting indoors is possible, but does not gain much time. If sunflowers are allowed to get root-bound, they will lack stability at transplant time, and will require staking. Optimal soil temperature for germination: 21-30°C (70-85°F). Seeds should sprout in 10-14 days.
Step 2: Starting
Sow seeds 5mm-1cm (¼-½”) deep. Space dwarf varieties 15cm (6″) apart, but give the giants lots of room at 1m (3′) between plants.
Step 3: Growing
To grow really big plants with really big flowers, enrich the soil with organic matter and incorporate 2 cups of balanced organic fertilizer per 3m (10′) of row, and irrigate regularly. When the plants are 30cm (12) tall, dissolve 5ml (1 tsp) of borax (for boron) in 350 ml (12 fl oz) of water and spread the solution over 5m (15′) of row. Be careful not to over-apply this solution. This application of boron will produce bigger seeds and flower heads. Do not apply boron to other garden plants. When the back of the flower head turns yellow, it is ready to be cut from the plant.
Plant dwarf Sunspot sunflower seeds directly in the garden in late
spring or early summer when all danger of frost has passed. Sunflowers
need plenty of bright sunlight and moist, well-drained, neutral to
alkaline soil. Plant small batches of Sunspot sunflower seeds two or
three weeks apart for continual blooms until fall. You can also plant
seeds indoors for earlier blooms.
Watch for seeds to germinate in two to three weeks. Thin Sunspot
sunflowers to about 12 inches (31 cm.) apart when the seedlings are
large enough to handle.
Caring for Sunspot Sunflowers
Water newly planted Sunspot sunflower seeds frequently to keep the soil
moist but not soggy. Water seedlings frequently, directing the water to
the soil about 4 inches (10 cm.) from the plant. Once the sunflowers are
well established, water deeply but infrequently to encourage long,
Read more at Gardening Know How: Growing Sunspot Sunflowers – Information About Dwarf Sunspot Sunflower https://www.gardeningknowhow.com/ornamental/flowers/sunflower/growing-sunspot-sunflowers.htm