Petunia Care

Petunia (Petunia spp.) is a genus of 20 species of flowering plants of South American origin. The popular flower of the same name derived its epithet from the French, which took the word petun, meaning "tobacco," from the Tupi–Guarani language. An annual, most of the varieties seen in gardens are hybrids. Typically 6-24 inch tall and up to 36 inches wide, this flower grows hardy in USDA zones 10-11. Petunias have wide, trumpet shaped flowers and branching foliage that is fuzzy and sticky. Bloom colors include pink, orange, purple, white, yellow, red, and bi-colored. Appreciating full sun, Petunias are great in borders, groundcover, containers and hanging baskets.


Planting Petunias

Petunias can be planted outdoors as soon as the threat of frost is over. Choose a site that will get full sun, as this plant does not flower well in the shade. Petunias are not picky about soil as long as it is well-draining and not soggy. If you wish, you can mix in some organic matter upon planting. Space Petunias 12 inches apart. Regular watering and plenty of sun will encourage abundant blooms.

Watering Petunias

Petunias are fairly heat tolerant and thrive in full sun. Because of this, regular watering is a must. Regular watering will ensure that this plant is in constant bloom. Unless it is extremely hot, weekly deep watering should be sufficient. Container grown Petunias dry out quicker in full sun; thus, they will require more frequent waterings. Do not allow the plant to sit in water as it can cause root rot.


Fertilizing Petunias

Petunias are known for their bushy colorful blooms. To keep your Petunia blooming strong throughout the growing season, it will require consistent feeding. This flower should be fertilized lightly every 7-10 days. A balanced water soluble fertilizer such as a 10-10-10 or 12-12-12 will satisfy this heavy feeding plant. You can also use fertilizers that specifically promote flower blooming. Water well after each application of fertilizer.

Pruning Petunias

Typically by midsummer, Petunia plants become very leggy. They will produce blossoms at the end of long leafless stems. To encourage more branching and better flowering, prune the shoots back to about half their length. Deadheading (removing old, dead blossoms) can be done as needed to improve the look of the plant and encourage more blooms. This will also prevent the seed pods from unnecessarily using the food supply. After pruning, fertilize and water well to promote more blooming.


Caring For Petunias in Pots

When planting Petunias in containers, it is important not to crowd them. Plant 3 plants per 12 inches of pot. Use a container that has good drainage holes. Because this plant likes heat and full sun, container grown Petunias will need frequent watering. Every few days, give them a long slow drink of water at the base of the plant. Petunias are heavy feeders. They will need to be fertilized weekly throughout the growing season.

Winter Care for Petunias

Petunias are typically grown as an annual and die off with the first frost. With a little effort, it is possible to overwinter Petunias and bring them back out in the spring. One option is to gather the seeds from the spent flowers and allow them to dry out over winter. Sow the seeds in the spring after the weather warms up. You can also store a container grown plant in a sunny area with temperatures around 50 degrees. In the spring, cut the plant back and return to the outdoor space.

Common Petunias Care Questions

How Do You Keep Petunias Blooming?

Deadheading petunias every couple of weeks will help to keep them full of blooms all summer long. If you find your petunias getting spindly and leggy, trimming the stems back by 1/4-1/2 will help encourage additional branching and new growth, creating a fuller-looking specimen!

What Temperatures Can Petunias Tolerate?

Petunias can tolerate pretty cold temperatures, as cold as 40 degrees but really they prefer nighttime temperatures around 55-65 degrees. If temperatures are going to be around the freezing mark, and you're not done enjoying them yet, you can save them by covering them with frost cloth, a sheet, or blanket, or simply bring them indoors. 

Do Petunias Spread?

If deadheading is stopped near the end of the bloom season, seed pods can form and the petunias may self-seed and reward you with new plants next season, though the flowers will likely not be as large, or the same color and the parent plant.

Are Petunias Annual Or Perennial?

Petunias are classified as tender perennials, and they will not survive a frost, even a light one. They are grown as annuals in most climates.

Do Petunias Like Sun Or Shade?

Petunias love the sun! The more sunlight, the more blooms!

How Long Do Petunias Last?

Petunias will last and bloom all summer long and into fall, until the first frost  However, they are technically tender perennials, you can bring them indoors and keep them through the winter as houseplants in a sunny window where they'll get at least 6 hours of sunlight. 

Are Petunias Drought Tolerant?

Petunias love the sun and the heat and most varieties (except those that are designed to spread) are drought and heat tolerant. Petunias in hangings baskets and containers are a little less tolerant, as their soil dries out more quickly. 

Why Do Petunia Leaves Turn Yellow?

Petunia leaves turning yellow is most often a nutrient deficiency in the soil. Nitrogen is the most common, or potassium, sulfur, iron, manganese, and/or magnesium.

Why Do Petunia Leaves Turn Brown?

Browning leaves on petunias is generally because they've been too long between watering but it can also be caused by water from the top and the leaves getting wet. It is best to water petunias at ground level to avoid getting the leaves wet. 

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Author Chris Link - Published 09-08-2021