Rose flowers drooping?

Too little water, too young a roses, extreme hot weather, chemical poisoning, and behavior specific to the variety can all cause blooms to nod. It's one of the features that David Austin breeds into many of his roses and is how many antique roses appear, so first be sure that you don't have a variety that nodding is normal. Ortho is overpriced junk, especially if it's the crap with the systemic insecticide included, which can also build up in your roses and cause all kinds of problems, including the weak necks that you describe. Improve the soil with lots of organic matter, manure, and alfalfa, and your roses won't need but the occasional snack in early spring before the microbes are warm enough to start breaking down the organic matter to feed them. Roses like a LOT of water. It's the most important "secret ingredient". Unless you have very heavy unimproved clay soil or garden in a bog, it's almost impossible to overwater them. Roses like full sun conditions, but this can be trying to them when temperatures soar into the upper 90's and above. Then, watering and more watering and more watering is key to keeping them hydrated and happy. Young roses also often improve in many respects as they age, including increased bloom production, better disease resistance, and thicker stems that hold their heads up better. If your roses are less than 3 years old, then perhaps you are a bit impatient in wanting a toddler to behave like an adult.