Sunflower seeds are best grown outdoors sown directly into a prepared seed bed. In truth, they will germinate with very little help, but to get the best out of them they will need to be planted into a nutrient rich soil, so add plenty of well rotted farm manure to the ground a few weeks prior to sowing, digging it in deeply. Try to avoid planting into light sandy soils – especially for the taller specimens – as they can be prone to blowing over in strong winds. After planting, it’s worth covering the newly sown seed with some kind of an open mesh, as birds, squirrels and other animals are more than capable of digging them up for a quick and easy meal. Depending upon your average day temperatures you can expect to see your germinating seedlings to appear anytime between 14 and 21 days
If you want to get a head start on the year then begin by planting your sunflowers indoors. This will need to be done about 6 weeks before the threat of late frosts are over – for most places that will be from mid to late February. Use individual pots containing a good quality seed compost, planting two seeds per pot. Cover the seed with ½ an inch of compost and water so that the compost is damp throughout. Now cover with clear plastic to help keep the compost moist and humid. As soon as the seeds begin to germinate the plastic will need to be removed in order to prevent fungal rots. A week or so later the seedlings can be thinned out to strongest specimen as they begin to show through the compost.
When planting them in the garden perhaps the most important thing to be aware off is the plants sensitivity to light and its ability to ‘track’ the sun as it travels across the sky. It is this ability that the plant has to do this – and of course its resemblance to the sun and its rays - which is why in English speaking cultures it has been given the name the sunflower. With this in mind make sure that you plant your sunflower seed in that part of the garden that is facing the sun, otherwise you will spend that year looking at the back of those outrageous flower heads instead of being able to get the full frontal effect- as it were!
Experience has shown that sunflowers can tolerate a certain amount of shade such as an east facing border, however they will grow their best in full sun.