Past Articles Library | How to Grow and Care for an Annual Favorite-Petunia
Petunias are a wonderful and colorful annual that is easy to grow. This plant produces blooms during the spring, summer and fall months, which makes it a good value when watching your landscaping dollar. While many nurseries only cover one or two different groups of petunias, there are actually four different types of petunias, which includes the grandiflora, multiflora, milliflora, and ground or spreading petunias. All of these varieties can be found in numerous colors, which includes pink, red, white, purple, and yellow.
Grandiflora is the most popular petunia in the annual flower market. This plant produces large blooms that can span three to four inches across. Some produce single blooms while others produced double blooms that have ruffled edges. Their growth pattern can be in a mound shape that can reach 12 to 15 inches in height while other grandiflora varieties have a tendency to cascade down. When using this type of petunia though, one will need to plant it in a container or hanging basket regardless of the growth habit. Why, you may ask. The reason is that while the grandiflora petunia is extremely beautiful, it is sensitive to rain, which causes damage to the leaves and flowers alike. To avoid Mother Nature’s damage, plant this variety in a movable container.
Multiflora petunias, as the name indicates, produce a lot of blooms but they are smaller compared to the grandiflora. Their blooms can be single or double but more commonly are found to produce single blooms. To get the most out of this variety, plant in mass groupings.
Milliflora petunias produce large amounts of blooms that are only one inch to an inch and a half in diameter. Due to their small size, this type of petunia works well as an edging plant and in a container garden.
The ground or spreading petunia is one that has many uses. First, this variety only reaches about six inches in height and if watered and fertilized properly will cover a large area in one season. They can be grown in hanging baskets or window boxes, which will enhance their two to three foot spreading habit. Another option for this variety is to plant it along a hillside or on top of a retaining wall. Again, both planting locations will allow the spreading petunia to grow uninhibited.
While petunias only really have one soil requirement and that is it needs to be well-drained, they do require a sunny location that receives at least six to eight hours of sunlight. If this sunlight requirement is not met, the petunia will bloom less.
Once the proper location has been found, the next step in this process is to improve the soil’s drainage ability regardless of what type you may have in your site. To do this, add two to three inches of organic material to the soil, which includes peat moss, manure and/or seasoned compost. Mix this organic material into the soil to a depth of 8 to 10 inches. Once this has been completed, add a balanced fertilizer such as 8-8-8 to the soil surface at a rate of one pound per 50 square feet and rake in.
Now, you are ready to plant your petunias. To begin this process, one will first need to dig the hole. When doing this step, make sure to dig the hole twice the width of the container that the petunia is in and at the same depth. Prior to removing your petunia from its container, make sure to do a dry run. This can be done by simply placing the container in the hole to check the depth and width. Once the hole is the correct size, it is time to plant the petunia but do not just yank the plant out of the pot. You can remove it in one of two ways. The first way requires you to tip the plant upside down in your hand. When performing this step, make sure not to break the plant off by crushing it in your hand instead allow the flower to fall between your fingers while you hold the container. Next, gently squeeze the sides of the pot and gently tap the bottom. At this point the pot should release from the root mass.
The other approach is to just cut slits down the side of the container and then remove the plant by the root ball and not the foliage.
Once the plant has been removed from its container, place in the hole, fill in, and continue until all the petunias have been planted. Make sure when doing this process that you space out your petunias so that they are a foot apart. After all the planting is done water in the garden space completely.
If you plan to plant your petunias in a container the process is much the same but instead of using a potting soil mix, choose a soilless medium. While you can purchase a soilless mix, it is just as easy to make one. To do this, combine four to six parts peat moss to one part each vermiculite and perlite. Add to this mixture a slow-release fertilizer that is designed for blooming plants.
Once that is done, pick the container you would like to use but make sure it has a drainage hole in the bottom. After you have your container, clean and sterilize it. Place drainage material in the bottom of the pot and fill ¼ to ½ of the way full with the soilless medium described above. Arrange the petunias and any additional flowers in the container prior to planting. Once you are satisfied with the arrangement, plant as you would in the ground.
While petunias are normally purchased as transplants, you can grow your own from seed. This allows the gardener to have a wider variety of types and colors of petunias then what can be found at the local nursery. But prior to ordering your seed, keep in mind that propagating petunias in this fashion can be a challenge even for the seasoned gardener.
To begin this process, one will first need to know their local frost-free date. This information can be obtained from your local extension office. After you have the date, count back eight to 12 weeks. This date will be your planting date. Next prepare your flats for your seeds, which means to clean and sterilize them prior to filling. Once that is done, fill with a soilless potting medium and water in.
Petunia seeds are small and if possible order pelleted seed, which is seed that has been coated with a material that makes them easier to handle. Next, sprinkle your seed on the soil surface and gently push down. Continue to plant your seeds and label each flat as you go. Once all the seed has been planted, gently water in again with a watering hose that has a fine mist nozzle on it.
The next step in this process is to cover the flat with a sheet of glass or clear plastic wrap. Place the flat in a location that is kept around 70 to 85 degrees Fahrenheit and in a sunny location that is away from direct sunlight.
In about 7 to 10 days, you should begin to see sprouts appear. Once that happens, remove the covering and place in a sunny location. Make sure the room temperature is kept at 65 degrees Fahrenheit during the day and 55 to 65 degrees Fahrenheit at night.
Once the petunias have three sets of true leaves, it is time to transplant them into individual pots. Place them back in a sunny location and feed with a diluted form of liquid fertilizer every two weeks.
Prior to planting outside, make sure to harden them off by slowly exposing them to warm, sunny days and moving them back in at night. This process should continue for 2 weeks before you leave them out all day and night.