Thanks! I use 90 liter containers to grow this kind of flowers, and I put them in hot place. Seems to that it need airy, sandy compost and plenty of calsiumstone.
I noticed also that there are some varietes whic are pollen free. No use for bees:
"Butterflies are attracted to `Russian Mammoth' and `Lemon Queen' as well. " Gardeners now have new choices of sunflowers perfect for cutting -- smaller-headed varieties such as `Italian White' (H. cucumerifolius) and pollen-free hybrids like `Del Sol,' `Sunbeam' and `Moonshadow.'