Early this month, pinch or cut back sedum (Autumn Joy type, not the groundcover type) to about 4 inches to reduce flopping. You can also pinch or cut back asters and Shasta daisies to produce compact plants that don’t require staking.
Fertilize your roses each month during the summer. Deadhead regularly and keep an eye out for mildew, aphid, black-spot or other problems.
Deadhead annuals to keep them flowering. Deadhead perennials to encourage a rebloom and to discourage heavy seeding.
If your spring bulb foliage has completely dried up, clear it away.
Deadleaf yellowing foliage from spring-flowering perennials.
Weed!
Remember to water – especially your containers. Push your finger deep into the soil to check for dryness. Try to water early in the morning so that there is less water loss due to evaporation and also so that the leaves can dry off a bit before the hot sun hits them.
If you have a bird bath, rinse it and refill it every day. Standing water can breed mosquitoes.
Take pictures!