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How to Grow Petunias in Containers

By Sarah Terry ; Updated September 21, 2017
Blooming petunias in a hanging container.

The petunia is a popular annual flowers, blooming readily and profusely throughout the summer months. Petunias are easy to grow in flower beds or in containers. They're often grown in window planters and hanging baskets, but they can grow in most containers. Petunias have trumpet-shaped flowers that come in many colors and are divided into two main categories: grandiflora and multiflora. Multiflora petunias have many small flower blossoms and grow in a more compact form, while grandiflora types are trailing, cascading petunias with larger blooms.

Choose a container that accommodates petunias spaced 6 to 8 inches apart. The container should have drainage holes in the bottom.

Plant petunias in well-draining, lightweight potting soil mixed with some bonemeal or superphosphate, according to the recommended dosage on the package. If the potting soil is heavier, mix in some sand or peat moss. Plant the petunias at the same depth as the nursery containers or flats.

Place petunias in full to partial sun where the plants will receive at least four to six hours per day of sunlight. You can set the petunias outdoors during summer in a sunny location or keep them indoors beside a south-facing, sunny window.

Water your petunias when the topmost layer of the potting soil feels dry to the touch, providing water until it begins to drain from the bottom of the container. Don’t allow the potting soil to dry out completely or the petunias to wilt. Take care, though, to not saturate the potting soil.

Feed your container petunias with a high-phosphorous fertilizer, such as a water-soluble 5-10-5 NPK (nitrogen, phosphorus and potassium) formula. Apply the fertilizer once every three to four weeks at a rate of 1 teaspoon diluted in 1 gallon of water.

Pick off the petunia flowers after they begin to fade and finish blooming. Deadheading the blossoms at least two or three times per week will prevent the petunia from forming seeds and keep the plant tidy.

 

Things You Will Need

  • Planter containers
  • Petunias
  • Lightweight potting soil
  • Bonemeal or superphosphate
  • Sand or peat moss (optional)
  • Watering can or garden hose
  • Water-soluble 5-10-5 NPK fertilizer

Tips

  • Pinch off the first flower blossoms on your petunias to encourage more profuse blooming. Also pinch back the stem tips when the petunias are 3 to 4 inches tall to promote a more compact form and healthier branching.
  • If your container petunias become "leggy," you can cut the stems back to about half their length during mid-summer. Water and fertilize the petunias after cutting them back, and they'll quickly develop new, healthier growth.

Warning

  • Don't wet the petunia flowers and leaves too much when you're watering the plants, because this can cause the foliage and petals to become spotted. If you're keeping the container petunias outdoors, move them to a sheltered spot during heavy rains.

About the Author

 

Sarah Terry brings over 10 years of experience writing novels, business-to-business newsletters and a plethora of how-to articles. Terry has written articles and publications for a wide range of markets and subject matters, including Medicine & Health, Eli Financial, Dartnell Publications and Eli Journals.