AAS Winning Petunias

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.

Maintenance

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.