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Selecting the best type of petunia

Petunias are one of the most popular annual flowers, and with good reason. There is an endless variety of colors from which to choose, and petunias bloom from mid-spring until frost in the fall. In the days ahead, many of us will be choosing some type of petunia to put in our beds, gardens or containers.

There are four main types of petunias:

Grandiflora petunias are the most popular because they produce large flowers 3 to 4 inches across, and may be singles or doubles. They also work in hanging baskets and are more suitable as upright plants, which develop into large mounds of flowers that are 12 to 15 inches tall throughout the summer. If you carefully space grandiflora petunias this distance apart when planting, the result is a continuous sea of color. Also, grandiflora petunias need to be deadheaded (pinch off the blossom when it fads, so no seed head forms) if you want them to bloom all season.

Multiflora petunias are more compact, and their flowers are a little smaller. However, they have many more flowers than the grandiflora varieties. Multiflora petunias are available in single and double blossoms, and will produce a mass of color. Like the grandiflora, they need to be deadheaded if they are going to continue to produce flowers.

In addition, milliflora petunias are more compact, and have abundant small 1 1/2 inch single flowers. They make excellent edging plants and work well as a filler plant in container gardens. Milliflora petunias also grow upright, as well as spill down over the edges of containers, while filling in and around other flowers and plants. Another outstanding characteristic of milliflora is they do not produce a seed, and therefore do not need deadheading to continue to bloom.

Groundcover, or spreading petunias, reach only about 6 inches in height, but spread over a huge area in one season when watered and fertilized. These are known as wave petunias, which will scramble down a hillside or spill over a retaining wall. Ultimately, they work wonderfully in hanging baskets. Also, groundcover petunias will drape 2 to 3 feet during one season, and will be so covered with flowers that their foliage almost appears hidden. They will also produce more flowers if they are deadheaded.

All these petunias are hybrids, which means their DNA has been genetically engineered to produce certain improved characteristics. You can buy seeds and start your own petunias, but they need to be deadheaded because they form seed heads. As soon as a plant forms a seed head, it senses it has accomplished its purpose and begins to shut down for the season. If it is deadheaded, the plant also continues to produce blossoms and a seed head in order to survive. If the plant is a hybrid, and you take a dry seed head, take the seeds and plant them. This will either produce a flower from some parent of the plant's past genetics, or it may not grow at all.

There are also petunia plants which are sold as individual plants by certain companies. These are more expensive than other hybrid petunias. Also, these plants have been genetically engineered to grow larger, have beautiful flowers like the multiflora and be disease resistant. They do not need to be deadheaded because they are sterile and do not produce seed. Additionally, these plants are grown after you cut from a plant that has been specially developed with certain desired characteristics. This requires more work to propagate, so these plants are also patented. If you have not tried one of them, do so and compare it to some of your other plants to see how they perform.

Petunias thrive in the hot sun and wind, and can withstand quite a beating. To produce a large, healthy-looking petunia plant, it will need fertilizer and water. Those plants in window boxes, hanging baskets and containers need a half solution of a fertilizer in water once a week. They also need to be planted in containers that hold a good amount of a soil mixture. Petunias are also lovely as a picked flower. Just be sure to remove any foliage that is below the water line of the vase. Petunia leaf foliage rots quickly in water, which causes the whole arrangement to die.

Kyle Schulz is a Wadena County Master Gardener from Sebeka, and the regular gardening columnist for the Wadena Pioneer Journal.