Why are my flowers wilting already?

I just recently moved into our house and the flowerbed in the front was disgusting. We ripped out the old bushes and replaced the rotted mulch and clay with garden soil. I planted a bunch of flowers and covered the open ground in mulch as I was told by my neighbor, but its been 4 days and they are all wilted. I planted petunias, delphiniums, foxglove, and dusty miller. I water them every morning- is that too much/too little? The first time I watered them I used that starter feeding liquid. Where am I going wrong? Its hot & humid during the day, kinda chilly at night- and that flowerbed gets sun all day long.