How to care for petunias


Petunias have long been a popular garden flower. Now with hardy hybrids available in colors other than standard purple, the plant is more attractive than ever. Blooms can be found in a range of colors from light pink to red and pale blue to deep purple.

Flowers are trumpet shaped. They may have veins in a contrasting color, and may have edges that are smooth or fluted, ruffled, or fringed. A few types have a mild cinnamon scent. As an added bonus, you may find hummingbirds attracted to the petunia beds.

The plants are available either in the larger single grandiflora or the double multiflora. They may range from 6 inches to 2 feet tall. An even smaller spreading type is used as groundcover. A cascading variety works well in hanging containers or window boxes. The smaller multiflora withstands wind and hard rains better than its larger cousin.

Learning how to care for petunias is not difficult. The profusion of color they lend to your garden easily repays the effort.


Choose a plot of land that enjoys full sun, although petunias will bloom in partial shade. They should receive at least half a day of sunshine. Soil should be somewhat sandy, slightly acidic, and well drained.

Petunias will do better if the soil is enriched with organic matter. Spread the organic matter on 2-3 inches thick. Then work it carefully into soil to a depth of 8-10 inches. It's important to work it into the soil well.



Petunias can be raised from seed. Begin inside 4-6 weeks before planting season. Seeds are very tiny, so you may want to mix them with fine sand to spread them evenly. Use a starter soil and sow the seeds on top. Press them down, but do not cover. They need light to germinate.

Keep in a spot where they receive indirect sunlight. Artificial lighting can speed the process. Water from beneath or with a fine mist to avoid disturbing delicate seedlings. Keep moist but not soaked. They should germinate in 5-15 days.

Transfer to individual containers when they have two leaves. Handle by the leaves, not the stems. Keep moist and gently fertilized until the root system is developed. Give the young seedlings a chance to become acclimated before transplanting them. They can be “hardened off” by setting outside on pleasant days.

Choose an overcast day for moving them permanently to the outdoors. Transplanting is a traumatic event for the tender seedlings. Water thoroughly and provide protection from the elements. Purchasing seedlings can simplify the process.


Spacing of the plants will depend on the variety you have chosen. Larger plants should be planted 12 inches apart. Miniatures can be as close as 4-6 inches. A ground cover plant should be spaced 1 to 1 ½ feet apart.

Planting should be done when all danger of frost is past. Ground should be warm enough to work. Plants will appreciate a mulch to keep moisture in. When seedlings are tall enough, add a 2-3 inch layer of organic material such as grass clippings or bark. Add a slow release granular fertilizer to give them a good start.


Petunias will need some attention once they begin to blossom. Modern varieties need little care. You may want to pinch them back at the top to encourage bushy growth. Their main need at this point is water. Their roots are shallow and dry out quickly. Keep them well watered through the hottest part of the summer.

If the plants get leggy and produce fewer flowers, they can be cut back. Pruning them back as much as one-half can give them new vitality.

Perennial or annual?

While technically a perennial, they are generally grown as annuals. Some varieties may survive the winter in milder climates. Petunias will thrive from June until the first frost. If planted near a wall that retains heat, they may survive even longer. If you pot a few, you can bring them inside and extend the time you can enjoy the blooms.

When petunias die off in the fall, clear the plant material from the plot of ground. Then the spot will be ready to work next spring. Keep track of the varieties you liked. You may decide to look for hardier plants for next year, or experiment with new color combinations.


Use a commercial fertilizer as directed. They will need feeding about once a month during the growing season. Plants in hanging pots will need more fertilizer to support their quick growth.

Pests & disease

Watch your plants for pests such as aphids and cutworms. Healthy petunias generally have little risk of insect infestations. Damping off is the most common problem. This can be prevented by maintaining the proper moisture and temperature conditions. If plants become disfigured or discolored, remove the infected parts. This should be adequate to prevent the spread of any disease.

The payoff

For a profusion of color in your backyard, petunias fill the bill. Just a few pointers about how to care for petunias will make your task easier.