1. Deadhead 

After the first and second bloom cycles, begin removing blossoms that are spent. Deadheaded plants will rebloom more quickly, are likely to grow stronger stems, and generally look more attractive. Cut the spent blossom back to the nearest five leaflets where the stem is about as thick as a pencil. Make sure the swollen eye (on which the new flower stem will grow) points to the outside of the bush. Leave as much foliage on the bush as possible. After deadheading, the leaflet at the cut may turn yellow and fall off. Don’t worry, this is normal. 

Deadheading allows the plant to channel its energy into producing more blooms instead of seed. 

2. Disbud roses.

 If you’re growing grandifloras and floribundas, a practice called disbudding can produce spectacular results. These roses normally bloom in clusters; the central flower blooms first, followed by the secondary buds. The central flower inhibits the development of the lower side buds. Remove it and the surrounding buds burst into a larger display. The summer months are an ideal time to open up the central area of each bush to improve air circulation and suppress fungal diseases.

Cutting off some buds will allow more room for remaining buds to grow larger. 

3. Mulch roses
Besides helping to retain moisture, mulching is also an effective weed control and reduces the need for cultivation, which, if done too deeply (more than 1 to 1-1/2 inches), can damage feeder roots. You can apply mulch to single plants or over a whole bed. Organic mulches, such as bark, grass clippings, rotted manure, straw, and shredded leaves, break down and improve the soil. Landscape fabric blocks light that weeds need for germination, but lets water through. Mulch after planting 2 to 4 inches, but don’t mound mulch around the base of the plants. If you experience problems with fungal diseases, remove the mulch in the fall each year. In cold winter regions, wait until the soil warms to replace it. 

Mulching roses also helps with weed control.