The best advice is to transplant annuals to the garden as soon as possible after bringing them home. Once they start blooming, most annuals will flower all season long, until cold temperatures or frost put an end to their display. However, to keep them flowering and looking good, you will need to perform some simple but easy maintenance. Deadheading is the most important task, and it involves pinching off old flowers just as they begin to fade. The reason for doing this is simple.
Annuals live to flower quickly, produce seed and die.
Pinching off spent blooms is quick and easy, and it ensures season-long bloom. If you ve fertilized at planting time as recommended with an organic or slow-release fertilizer, you shouldn t have to fertilize annuals again during the season. With annuals, the flowers are the thing, and overfertilizing can lead to lush foliage growth, which is really beside the point. The primary exception is container-grown plants, which usually need to be fertilized every couple of weeks to maintain a colorful show. Annuals have small, shallow root systems and so require a regular supply of water.