Keep this in mind and always buy your house with a back yard to the west of the house. Read the package for the specific time for the variety you acquire. If you have a choice, sandy soils are not recommended as they are easily uprooted in loose soil. Rich soil is always helpful, but not an absolute requirement for the big and strong plant. Contrary to it's name, we found they will tolerate some shade as we put them against an east wall of our house every year.
Deep roots help sunflowers to withstand most droughts.
They will benefit from a douse of fertilizer when you apply it to the rest of your garden. Apply a little extra phosphorus and potassium when the flower bud begins to develop to promote bigger blooms. One or two will not seriously shade the vines. Make sure not to plant them near their tap roots for the vines. Pull out a seed and open it to see if it is full.