Pulse watering is worth looking into if you are growing in zone 10. Basically, it's less water more frequently, allowing the plants to take sips to stay hydrated through the day. Check out the link describing it... Great info on the site about other topics, too.

Winkie Dahlia is in a very hot part of Australia, and John has figured out how to get dahlias to thrive in extreme heat. Heard him speak at the national show this year, and got to known him a bit. He has a wit about him that'd make your eyes cross... Laughed so hard my sides hurt!

Here is a link that might be useful: Pulse watering from Winkie Dahlias