Care and maintenance for flowers and roses depends on the type of flower, with annual flowers generally needing less care than perennial plants. Try to make sure that your flowers are getting enough water and trim perennials like Knock Out roses often enough to keep them under control.
The type of flower is an important factor relative to the amount of care and maintenance that you might need to perform. In many cases you can just plant your flowers or flower bulbs in the fall or spring and let Mother Nature do the work, especially for annual flowers. Most annual flowers don't really need any fertilizer because you are not trying to grow a long term plant by definition. For perennial flowers and roses, you can add some fertilizer each spring for the first few years, although usually adding some manure and compost when planting them will give them a sufficient amount of longer term nutrients.
Obviously it is important to make sure all of your flowers and roses have a sufficient amount of water. Make sure that you always have mulch around all flowers and roses, as this will help them retain moisture. To check if your plants need watering, brush back some of the mulch around one or two of the plants in the area and see if the ground beneath the mulch feels dry or moist. If it is moist, you are usually okay but if it feels dry, then you probably should water, especially if there is no precipitation in the near term forecast. Also be sure to do this same type of checking in the winter for perennial roses and flowers, as you really don't want plant roots to ever become "freeze dried", as this can kill even an established plant. When you do water the plant, do so at a slow rate so that the ground can absorb the water and not just run off. Observe the ground around the plant when you are watering - if the water is absorbed rather quickly then continue watering, but if the water starts to puddle, then stop watering the plant.
You can trim or prune most flowers just about anytime, but of course if you trim new buds you won't get to enjoy those flowers. For plants like Knock Out roses, you sometimes have to just go ahead and trim off buds to keep the rose plants from getting out of control. If you plant Knock Out roses adjacent to your house, then you will probably want to trim them so that the rose plants don't reach your siding as the wind can cause them to scratch the siding on your house. I have to trim my Knock Out roses about every 2 weeks during the peak growing season to keep them from reaching the house and to maintain the right height and shape of the plants.
