Their flowers fall cleanly from the plant after fading and do not need to be manually removed. Others, such as marigolds, geraniums, zinnias, calendula and dahlias will need to have faded flowers removed. Deadheading can be done with pruning shears or sometimes with the fingers. A few annuals, primarily petunias, snapdragons and pansies, may need to be pinched back after planting or after the first flush of bloom to keep them compact and freely flowering. As new hybrids are created, this is becoming less of a maintenance requirement.
Annuals are generally trouble free under proper cultural conditions.
However, there are some common pests to be on the lookout for. When this can't be done, fungicide treatment may be necessary. The most common are aphids, white fly or spider mites which are easily controlled by various pesticides. Mites and white fly are less of a problem when plants are frequently watered. High temperatures increase insect populations necessitating more frequent pesticide treatment.