Double Pink Lilac Petunia. Picture courtesy Ball Horticultural CompanyDescription, History & Interesting Facts:
Petunias are popular low-growing annuals that originate in South America. Thousands of hybrids have been bred throughout the years and the flower sizes and shapes vary greatly.
Some varieties have darker veins in the flowers, stripes or frilly edges. Others have small single flowers in profusion and then you get the huge frilly, double varieties.
They are available in an outstanding array of colours varying from fiery reds, burgundy and purples, to all shades of pink, lilac, blue, yellow and white.
In the Garden:
Petunias bloom continuously all season with little maintenance and make perfect centre pieces to mixed plantings in pots, hanging baskets and window boxes. They are excellent border plants and if planted in mass, will provide brilliant colour for months on end.
Daddy Mix Petunia. Picture courtesy Ball Horticultural CompanyUse the cascading varieties in containers and the compact varieties in the garden.
The different varieties vary in height and spread so check carefully before making your selection.
The two oldest types of petunias are 'Grandifloras' and 'Multifloras' and both grow in a mound-like shape. Grandiflora varieties have larger flowers, but multiflora varieties hold up better in the rain.
Double Petunias
Double Petunias are grandiflora hybrids that produce fewer but large double blooms. They are beautiful in hanging baskets, mixed with other annuals like alyssum.
Single Petunias
Single Petunias like the 'Carpet Series' are very compact growing and excellent for garden beds and borders.
Petunia Easy Wave Blue'Wave', 'Supertunia', 'Cascadia' and 'Surfinia' Series of Petunias
Certain varieties like the 'Wave', 'Supertunia', 'Cascadia' and 'Surfinia' series of petunias are most popular because they make an excellent groundcover for large areas and can be used as bedding plants or trailing in containers.
These are actually short-lived perennial plants that can last up to two years before being replaced. They will grow about 20cm tall and 90cm wide, depending on how closely they are planted together.
'Tidal Wave' Petunias (Hedgiflora)
'Tidal Wave' Petunias grow outward and upward, forming a dense, mounded hedge. Their height will depend on how closely they are planted together. If spaced about 30cm apart they will grow 40 to 55cm tall and if spaced 60cm apart, 20 to 30cm tall.
These versatile plants can even be trained to grow as a creeper if they are supported by a trellis.
Cultivation/Propagation:
Petunias can be planted almost all year round in South Africa and are semi-hardy to moderate frost.
They love full sun (at least 6 hours a day).
Plant them in very well-drained, composted soil.
Petunia Easy Wave RedExcessive rains will ruin the flowers and can even cause the plants to rot, so be judicious with water and make sure the soil is well-drained. Too much water will cause the plants to become "leggy", with lots of stem and few flowers.
To keep them blooming for longer feed them monthly with a granular fertiliser or a foliar spray for flowering plants.
Petunias must not be planted in the same soil season after season as harmful organisms can build up in the soil and eventually kill the plants.
Older varieties of petunias require diligent deadheading or they will stop blooming. Even the newer varieties that say they don't require deadheading will benefit from a pinching or shearing mid-season. When the branches start to get too long and you can see where all the previous flowers were along the stem, it's time to cut them back and refresh the plant.
Seeds are best sown in seedling trays and can be sown almost all year round as long as temperatures are not below 25°C. The seeds need light to germinate, so don't cover the seed with soil but rather sprinkle the tiny seeds onto the surface of the soil and gently press them in. Petunia seed can start germinating after a few days or can take up to a week or more, depending on conditions. Place the trays in a warm place with bright light.