How to Grow Petunias in a Topsy Turvy Container

Wait until all danger of frost passes, and hang the upside-down planter in a sunny location that receives six to eight hours of direct sunlight each day. Although petunias perform best when exposed to full sun, they can tolerate several hours of shade -- preferably afternoon shade.

Water your petunias whenever their soil dries, adding water until it runs freely through the planter's bottom. The petunias may need watering twice per day during hot weather. Petunias use a lot of water while growing, and soil tends to dry quickly in an upside-down planter. Providing your petunias with some shade during the heat of the day may reduce drying of their soil and, therefore, reduce your petunias' watering needs.

Apply a water-soluble fertilizer designed for blooming plants. Mix it at a rate of 1 tablespoon of fertilizer per 1 gallon of water, and give it to your petunias on a seven- to 14-day cycle. Use a water-soluble fertilizer for blooming plants that is also a foliar feeder to gain double benefits from the fertilizer application. As the excess fertilizer drips through the container's bottom, it lands on the petunias' foliage, which absorbs it.

Remove the petunias' faded blooms by snapping them from the plants with your fingers. The task, called deadheading, keeps petunias looking good and encourages further blooming. Removing the old flowers sends a message to the plants that they have not produced enough flowers to set seed. They respond by producing new blooms. Petunia varieties labeled as self-cleaning do not require deadheading.

Pinch off the new leaves on branch ends if your petunia plants produce long vines with few blooms. Doing so forces new growth along the stems and creates dense foliage that will support blooms.

Prune long vines back by one-third to keep your petunias producing flowers all summer. By pruning a few vines each week, you can force new growth at the base of the plants without sacrificing the existing blooms on the longer vines. After several weeks, entire plants will be rejuvenated.