Tips for growing sunflowers

Here are some basics on growing sunflowers:
Plant them in full sun.
Russian Giants, Kong and Mammoth varieties grow as tall as 15 feet and have flower heads as large as 20" in diameter. If using a container you'll need a pot at least 15" inches deep and 15" in diameter (or larger) to grow these giants.
Sunflower roots grow deep and spread wide if you are using a container make sure it is big enough
Tall plants may need staking.
Keep the soil moist and fertilize them with a 1/2 strength organic liquid fertilizer every two weeks.
Sunflowers need lots of water (plants 6 feet tall can consume 8 gallons per week), but over-watering them can cause deformed seed heads. Use well-drained soil and keep the soil evenly moist. Water seedling deeply once per week for the first month so they develop deep roots. After that, water your sunflowers lightly every day.
Sunflowers are called sunflowers for a reason. They need sun. Make sure that the location you choose for your sunflowers gets full sun.
You do not need to worry about soil too much. Sunflowers are not picky about the conditions of the soil, but they are plants. They will do better in better soil.
Sunflower seed shells do contain a substance that is toxic to grass. So, you will need to either harvest the sunflower heads before the seeds begin to fall out or you will need to plant your sunflowers in a location where you do not mind any nearby grass being killed.
Keep in mind the height of the sunflower variety you have chosen. A giant, twelve foot variety will end up acting very much like a small tree and may shade the surrounding flowers – we are growing Russian Giants.
Protect from slugs, ants and pigeons. Use crop rotation in your garden to avoid diseases like Sclerotina (white mould) which makes their stalk and head rot. Other diseases to watch out for are downy mildew and rust. Pesky insects like moths are attracted to the sunflower head at flowering time; their larvae feed by tunnelling through the seed. You can protect your sunflowers by covering the heads with plastic netting which should also deter birds. Sunflowers are ready to harvest when the back portion of the head turns brown.
As mentioned above, sunflowers can also help you to attract local birds to your garden. When the growing season is coming to a close, you can harvest your sunflower heads and use some of the seeds to feed the birds over the winter. You have two options when using sunflower seeds to feed the birds. The first is that you can simply leave the sunflower heads outside for the birds. This option is the easiest but be warned that the birds will make a mess when pulling the seeds out of the sunflower head. Your other option is to remove the seeds from the head and to put them in your bird feeder. This method is a little more work but will be neater in the long run. Also, putting the seeds in a birdfeed will also help to keep your feathered friends safe as the birdfeeder will be up off the ground and out of reach of many of the animals that eat birds.