The Sunrich series of hybrid sunflowers was bred with the florist trade in mind. These are highly uniform annuals that mature in 60 to 70 days from direct sowing, producing a single, upright stem, about 1.2-1.5m (4-5') tall. The flowers are very round with dense numbers of petals, but the flowers produce no pollen, so they won't make a mess when they're cut and brought indoors. They make really excellent, long-lasting cut flowers, with blooms 10-15cm (4-6") across.
Sunrich Lime sunflower seeds are a good choice for florists and wedding planners. Their striking flowers have tightly packed lemon yellow petals around a lime green centre. The combination of colours is sensational.
Sunflowers will grow in just about any well-drained soil, and they are drought tolerant. To grow sunflowers from seed, to grow really big plants with really big flowers, enrich the soil with organic matter and incorporate 2 cups of complete 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 big seeds and flower heads. Do not apply boron to other garden plants. Annual flowers that can grow to incredible heights in just one season.
Season & Zone
Exposure: Full sun
Direct sow mid-April to late May. 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.
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.
When the back of the flower head turns yellow, it is ready to be cut from the plant.
Sunflowers planted near rows of corn are said to increase yields. Aphids may be herded by ants onto sunflowers without causing the plants any harm. Sunflowers can be used to draw heavy metals, toxins, and even radiation from soil, but should be burned at the end of the season if grown for this purpose.
More on Companion Planting.