Everything You Need to Know About the Petunia

Petunias are among the most popular plants for gardeners and landscapers who want to add a splash of color to their beds. They’re most often grown as annuals. Although they are believed to be one of the easiest flowers to grow, in order to get the very best results, there are a few things that you need to know about their care. The petunia is such a versatile flower that there is a lot to learn about the different types, their maintenance requirements and what you can do with them. If you’re a petunia enthusiast then you’re in the right place. Here is your official petunia guide that will tell you everything you need to know about the petunia.

What is a petunia and how many kinds are there?

There are four main groups of petunias. There are Grandiflora petunias, Multiflora, Milliflora and Spreading or Wave petunias. You can probably tell from the descriptive names that the Grandiflora varieties have larger blooms which make them popular choices for hanging baskets or container growth. Multiflora petunias are the plant type that is covered with smaller flowers, but there are usually many more of them. They are more frequently used for mixed borders and as color accents in flower beds. The hardier of the two is the Multiflora which is more tolerant to rain and damp conditions while the Grandiflora does not tolerate rainy conditions as well.

More about the Grandiflora vs Multiflora

Grandifloras were developed in the 1950s and the blooms typically reach a size of 5 inches across. They do best when the weather is not excessively hot or humid. In extreme heat or rainy conditions, the plant becomes tired and by the middle of summer, they tend to become spindly with less spectacular blooms. Multiflora petunias feature smaller plants which produce abundant small blooms. This type is a better choice for windy environments because the stronger stems make them heartier and the blooms tend to last longer.

Milliflora Petunias

Spreading/Wave Petunias vs Milliflora Petunias

Spreading or Wave petunias were developed by the Ball Seed Company and they are known to be fast growing, producing multiple blossoms. This special hybrid petunia starts blooming in early spring and they continue through the end of the fall growing season. They are an exceptionally hardy petunia type that tolerates wet weather, heat, humidity and cold better than the other three varieties. They’re low maintenance plants which are popular among gardeners who love a lot of color but prefer the low maintenance hearty type. The cascading type of wave petunias are also used as a ground cover because they spread out and bloom profusely. They also makek nice additions to flower baskets because they tend to trail down.

Milliflora Petunia plants produce the smallest blooms but they make up for the small one inch across size with abundant quantities. They’re excellent border plants and if you’re looking for variety, they offer a great way to diversify a planting basket or flower bed. This versatile petunia type can be used in containers or in flower beds as borders and they can be planted close together for an even more dramatic effect.

Limitless choices for diversity

Petunias provide a great way to diversify a flower bed or basket because there are so many different types and varieties available under the four major groups of petunias. You can create accents using petunias or create a petunia flower garden that features a variety of sizes, colors and patterns. The number of hybridized varieties which have been created is almost limitless and each has their own distinct set of characteristics in colors and color combinations, bloom size, plant height, growth habit and environmental tolerances. Now that we’ve discussed the versatility of this amazing plant, let’s move on to the propagation, planting and maintenance.

How to grow petunias

Petunias are most commonly grown as annuals, but they could be grown as perennials if you live in the nine through eleven planting zones. You have a couple of choices for starting your petunia garden. You can either start with seeds or you can purchase them from a professional grower such as a nursery. The plants obtained from reputable nurseries are the better choice because they’ve already been nurtured, in most cases, to the blooming stage and it saves a lot of time, but we’ve included directions for growing them from seed if you enjoy the excitement of starting from scratch.

Planting Petunias from seed

Start with the seeds of varieties that you want to grow for your garden and buy the seeds from a reputable vendor. The seeds should be planted 10-12 weeks prior to outdoor planting, which ideally is after the last frost in spring. The date varies in accordance with your location. It’s best to use small peat pots because they are made of organic materials that will disintegrate into the ground over the summer. Fill the peat pots with high quality potting soil, sprinkle the seeds on top of the soil without covering them and expose to sunlight or a grow light. They’ll need plenty of light. Water them by putting water under the pots in a water proof tray so it is absorbed through the bottom. Keep the plants in a warm and sunny spot until they germinate. it could take between 5 to 15 days so be patient. Water as needed to keep soil moist but avoid over-watering. When your plants have reached the three leaf stage, they are ready to transplant outdoors in an area that gets full sun preferably, or partial sun in holes that are 6 to 8 inches deep and 12 inches apart, and fertilize with a water soluble product following recommendations on the label.

Caring for your petunias

Petunias are an easy plant to grow and maintain but they do require some care. It’s important to water these plants as needed. it’s a good idea to let them become a little dry, but not for extended periods of time. For the best results, water as needed but be careful not to over-water and use a method that does not soak the blooms because an excess of water on the flowers can cause them to deteriorate. A drip system works well. Also, too much watering can cause your plants to form long thin stems with fewer blooms. If you plant them in containers and the conditions of the environment are dry and hot you may need to water them daily.

Most common problems with petunias

Even though some varieties of petunia plants are resistant to harsh environmental conditions, there are problems which commonly arise that may require your attention. One of the biggest problems that requires troubleshooting is pest infestations followed by diseases in petunias. If you notice that your plants are failing to thrive, then it’s a good idea to get to the bottom of the problem right away before it gets out of hand.

Pest damage

There are several types of garden pests that can damage petunias and even kill the plants if not taken care of. The most common are caterpillars, followed by thrips, spider mites and mites. Caterpillars like to chew off the foliage and if you have an infestation they can decimate your plants in a short period of time. Caterpillars are the easiest pest to identify because you can see them on the plants. If you’re against the use of pesticides, simply go out a few times a day and remove them from the plants, placing them in a hot water filled bucket and throw them away. If this doesn’t get them all, an insecticide is the only remaining course of action. other pests which are harder to see such as microscopic pests can be diagnosed by small webs on the plants or if your plants begin to lose leaves or change colors. Neem oil is a common solution that is effective and you just need to spray it on the plants. This remedy works for thrips, mites and spider mites, which are also known to introduce viruses into the plants.

Powdery mildew

If you notice a powdery substance on your petunia plants near the stem and the root, or if there are yellow spots or patterns on the leaves, it could be because of overcrowding the plants or from over watering. Thinning or re-planting is the best solution to give the plants better air flow.

Most fragrant types of petunias

It’s been difficult to predict which types of petunias will deliver the most pleasing fragrance, if any, and you won’t usually find this characteristic in the description of a catalog or website selling them, but there are some types that have a tendency to produce scent. one of them is the Tumbelina mixed perfume Collection. It hails from Britain and also features double flowers. Another is the P. axillaris species and you can grow them from seed. The Old Fashioned Climbing petunia is a hybrid of an heirloom variety which is reported to have a delightful fragrance in the evenings. The flower colors are white, purple, pinks and shades of lavender. The plant blooms through the summer and the fall seasons a an annual that is self seeding so new plants will come up the following year if they are allowed to remain on top of the soil. The blooms range from three to five inches across and it’s available at Select Seeds.


Most gardeners don’t take the time to prune their petunias simply because they are an annual that will need to be replanted the following year, but they are a plant that requires pruning to get the very best results in terms of bloom yield and plant healthy. It’s not difficult to do and it only takes a few moments of your time, but there are a few things that you need to know in order to do it the right way. The process is also called “cutting back.” It is recommended that you trim a few stems off each week, cutting just above a node on the stem. This practice encourages blooming in plants with spent blooms. The result from pruning will be healthier plants and a longer blooming season. It’s recommended that you check the plants at least once a week and remove all of the withering brown flowers that are spent simply by pinching them off and removing the deadhead from the plant completely. If you can’t get the entire part of the spent flower off with your fingers, it’s okay to use pruning shears. Also, if your plants get too leggy with long stems and few blooms, it’s a good idea to prune the long stems in half, being careful to take them off at a node, but make sure that there are still leaves left on the stem.


Petunias are a wonderfully diverse plant and most varieties are easy to grow and maintain. Some of the newer hybrids require even less care and are more highly resistant to extreme weather temperatures and conditions, but it’s always a good idea to do a little research on the precise varieties that you choose to grow in your garden as some have slightly different care requirements that can make a difference in how well they produce and the health of the plants. They offer several different colors, patterns and sizes that they’re fun to work with if you like diversification in your flower beds. Now that you know everything there is to know about the basic types and care that is required, you can grow petunias like an expert horticulturist.

Similar Posts

Leave a Reply