My soil is sand based (as opposed to clay) and it dries out very quickly so I add tonnes (literally) of horse manure. Also in this weather there is no alternative to daily watering. I do mine after the sun has gone down but you could do it first thing in the morning!

Humus and more humus and then add some more. We had a sand garden and as Ian says , we added tons of manure every year. Sadly it is not a one off thing either, if the soil is well drained then you will be adding humus every year.

I have this very same type of garden/soil too and echo everything that Ian and Owdboggy say.
If you want an ornamental/flower garden grow plants that like that situation and accept that there'll be a lot that you probably won't be able to grow.