What’s not to like about petunias?
These incredibly versatile plants come in an abundance of bold colors, are widely adaptable, and largely pest and disease-free. They are low maintenance and drought tolerant, available nation-wide, are a great value, sport a variety of forms and colors, and some even exhibit a light, sweet fragrance. Additionally, these fail-proof, tried-and-true beauties have the largest number of AAS Winners in any one class-almost 70 different varieties!
Though generally treated as annuals by most gardeners, technically they are tender perennials and are members of the potato family. Today’s feisty hybrids are the descendants of two lanky, tiny-flowered South American species. First discovered in the late 1700s these wild varieties quickly captured the imaginations of European breeders who began crossing them in search of the perfect petunia – a plant with large, beautiful flowers in a variety of colors.
After World War II, better quality petunias came with the development of the F1 hybrids. Some of the first F1 petunias to win the AAS award were Silver Medal and Ballerina. As breeders developed new hybrids, it was now possible to regulate the growth from an open, floppy form to a bushier type with better weather resistance, an increasing range of colors, and a far superior ability to weather the rigors of summer.
As changes and improvements continued, plants started to be categorized as grandifloras or multifloras. The first truly red petunia, a multiflora called Comanche won the AAS award in 1953.
Then, a class of spreading petunias was achieved by Kirin Brewery in Japan with the 1995 introduction of AAS Winner Purple Wave. The original Wave series of petunias are easy to care for, flower freely, offers a thick, ground-hugging sea of color, need no deadheading, are incredibly weather resistant standing up well to rain and wind, and are virtually disease-free, making the “delicate” landscape petunia a thing of the past.
The original ‘Purple Wave’ has been joined by Easy Wave®, Double Wave® and Shock Wave® – each series sporting either larger, smaller or double blooms and more mounding or spreading habits. Another series, Tidal Wave®, is in an enviable class of its own. Referred by some as a Hedgiflora, it is the biggest of the Waves spreading to a whopping 5-foot diameter.
Additional Notable AAS Petunia Winners
Grandiflora: large-flowered blossoms (4-5”) of both single- and double-flowering cultivars form mounds of colorful solid, striped, deeply veined, variegated, or edged in a contrasting shade called picotee. Best is a cool, dry sunny environment in protected areas and dislike hot, wet, or windy conditions; work well in both containers and beds.
Multiflora: compact plants with smaller (1.5-2”) flowers that bloom prolifically and freely all season long. These plants have single or double flowers and are available in a rainbow of colors, often with contrasting centers or stripes. Best for wetter climates and perform admirably in adverse weather conditions.
Milliflora: petite, (1-1½”) blossoms produced with wild abundance that cover the plant with beautiful vibrant colors. Perfectly suited to containers, hanging baskets, miniature gardens and as edging plants.
Spreading: low-growing(4-6”) plants that can spread up to 5 feet across. These are fast-growing plants with excellent heat and drought tolerance, require very little maintenance, and make excellent flowering ground covers.
Floribunda: an improved multiflora petunia bred to have larger single- and double-flowered varieties that bloom earlier while producing an abundance of flowers. Like the grandifloras, they flower earlier, yet tolerate both hot and wet periods, perking up quickly after every rain shower.
Growing from Seed:
The petunia seed is tiny, so starting from seed may seem daunting; but it really isn’t that difficult. The advantage of starting from seed is cost-effective and brings lots of new and different varieties to your garden. Keep in mind that many of the newer cultivars are vegetatively propagated so are not available by seed.
- Start indoors 10 to 12 weeks before the average last frost date in your area.
- Use a prepared soilless mix for starting seeds. Shallow containers are best and should be clean with good drainage holes. Previously used containers should be washed in soapy water and then disinfected by dipping in a solution containing one-part bleach and nine parts water.
- Fill the container with the mix and press lightly to firm. If the mix is dry, moisten before filling the container. Spread the seeds sparingly on top of the damp potting mix. Do not cover the seeds as they need light to germinate. Water with a fine mist. Cover the container with clear plastic wrap or place it in a plastic bag closed with a twist tie to keep the mix from drying out while the seeds are germinating.
- Store the container in a bright, warm (70 to 80 degrees F) place, but not in direct sun, until seeds begin to sprout. When seedlings emerge, remove the plastic cover and place the container under fluorescent lights or in a bright, but cooler area of the home. Grow lights should be no more than 4 to 6 inches above the growing plants and should be left on for 14 to 16 hours daily.
- When seedlings have two sets of true leaves, transplant into 2-3” pots. To keep the plants from getting leggy, keep them under fluorescent lights or in a sunny window. Allow the potting soil to dry between waterings and fertilize every two weeks with a dilute fertilizer solution. Harden off the seedlings by placing plants in a shady, protected location outdoors; gradually exposing them to longer periods of direct sun. Bring plants indoors if freezing temperatures are predicted.
Purchasing and planting Petunias
- Look for healthy plants with clean, green foliage. Avoid those with water-logged or dried out soil or any with pests and diseases like powdery mildew.
- Wait until the soil warms to about 60 degrees F and the danger of frost has passed before transplanting. If possible, transplant petunias on a cloudy, breezeless day. If the weather is hot or windy with few or no clouds, provide some protection from the midday sun for a few days.
- Petunias perform best in full sun but can handle partial shade in the hotter parts of the country. They require moderately fertile, well-drained soil. Poorly draining soils can be improved by incorporating compost, peat, or well-rotted manure.
- Always check tags for planting instructions.
Petunias don’t require much care, but they do benefit from a little attention.
- During dry weather, water deeply once a week for petunias in beds and borders.
- Plants in containers, hanging baskets and window boxes will need watering when the soil becomes dry – that could be daily – and fertilized every couple of weeks with a dilute fertilizer solution.
- Many of the new cultivars are bred for compactness or mounding and require no pinching back or deadheading. But as a general rule, to encourage additional blooms and improve plant appearance, remove the spent flowers on grandiflora and double petunias. The smaller flowering types are self-cleaning and don’t require deadheading.
- After pruning, fertilize and water the plants to promote new growth.
“This post is provided as an education/inspirational service of All-America Selections. Please credit and link to All-America Selections when using all or parts of this article.”