September Petunia Persuasion

Petunias are one of the most recognisable and popular of the ornamental bedding plants. This is probably due to their hardiness coupled with their ability to bloom prolifically. There is a Petunia for every season and for every garden.

Petunia xhybrida is part of the Solanaceae family. This is a varied family of plants including members such as Potato, Tobacco and Capsicum as well as ornamental favourites such as Nicotiana, Salpiglossis and Schizanthus. Petunias are native to South America but thanks to modern breeding they have now become acclimatised to most parts of the world.


Petunias of days gone past were grown and used as perennials. The modern hybrids are used as annuals although in the warmer year-round climes, they will easily cross over from one season to the next. Your cue to remove them from your garden is when they become scraggly and you see more foliage than flower.

Petunias are herbaceous. The foliage is mid green in colour. The stems are thick, fleshy and hairy. Individual leaves are shaped like elongated ovals with rounded or slightly pointed tips and smooth edges. They are soft and hairy. They range from 2 – 8cm in length.

The traditional shape of the Petunia flower is that of a trumpet with smooth or fluted edges. Modern hybrids offer you a range of double, fringed or frilly varieties. Despite these variances the basic trumpet shape is still quite distinct. The flower size can vary from 2-13cm.

There are three popular types of Petunia: grandiflora (large flowered); multiflora (many flowered); milliflora (thousand flowers):

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The most popular is grandiflora. Producing fewer flowers than the multiflora, they have large showy blooms of 10-13cm which are beautiful to behold. These large flowers tend to be less tolerant of heavy rainfall and the delicate petals soon wither away. The plant itself is more vigorous in habit and spreads easily. Regular deadheading is required to ensure continuous flowering.

Multiflora Petunias are known for their mounding growth habit and abundant, colourful blooms. The 4-6cm flowers recover well from seasonal storms and are fairly tolerant of full sun and high heat. These too should be deadheaded frequently to encourage blooming.

Milliflora Petunias bear dense, bushy foliage and clusters of petite flowers. These heat-tolerant plants do not need pruning or deadheading to remain in bloom, producing wave after wave of eye-catching 2-3cm blossoms. Their compact growth habit is particularly well-suited to containers, and as a result, this type of petunia is often found flourishing in window boxes, hanging baskets and flower pots.

All Petunias should be planted in composted and well draining soil. They prefer full sun but can tolerate a little bit of shade. They require less watering than most annuals but you need to be vigilant at the height of summer, do not allow the soil to dry out completely.  The plants will benefit enormously from a monthly feed with a soluble multi-feed.

Petunias come in a wide range of colours and forms: blues, reds, purples, burgundy, lavender, pinks, rose, yellow, white. These colours are further divided into clear colours, picotees, veins and stars. There are double flowered Petunias, frilly and ruffled ones. There is a Petunia for hanging baskets, one for pots, window boxes, flower beds, rockeries. There is a Petunia for wet summers; one for dry summers you will even find a Petunia that flowers in winter. The choices really are endless. Your biggest dilemma will be to decide what NOT to take home!

Did You know?

Some Petunias have a delicate fragrance that becomes more evident in the evenings?

Happy gardening!

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