These are my absolute favourite flower. The electric blue shades are stunning (they flower in other colours too - white, pink and more but why bother when the blue is so gorgeous?). I'm also very happy that my experiment planting them on the north side of a fence where they get about 2 hours of sun a day worked!! Delphiniums supposedly love sun but I've always grown them in partial shade - they flower just fine and require less water this way.
Unfortunately, staking them is a bit of an art. There are several ways to do it:
1. The fairly easy way. Since you need to stake them long before they flower, put tall stakes in early. Loop some garden twine around the stakes, making a circle around the plant, just under the top of the plant. As it grows, add more loops of twine higher up the stake. One problem with this method is that you have tall stakes sticking up way above the plant before it gets tall enough to hide the stakes. Also, if you don't stake each individual stem, you still risk them flopping over within the area of the twine if the flowers get too heavy. Sometimes I just cut the flopped ones and bring them inside in a vase.
2. The perfectionist's way. Place several stakes around the plant before it gets too tall. Use small loops of twine around each stem, and tie each stem to the nearest stake. Repeat this higher and higher up the stake as the plant grows. If you're really anal, you can even replace the stakes with taller ones as required, so you don't have bare stakes sticking up way above the plant early in the season. Nobody ever said perfect delphiniums were easy.