Petunias: Flowers that love the summer heat

Petunias and calibrachoa seem to have been made for the heat. At the recent BallStraathof Open Gardens in Honeydew, containers filled with Easy Wave petunias and a variety of calis were in full bloom and stayed incredibly fresh despite the heat.

As patio plants they passed with flying colours, and, as Kathy Varney of BallStraathof said, “both grow into mounds with a controlled growth that holds its shape which is what we want from container plants”.

Petunias in all their variations are vintage garden plants, but Easy Wave petunias are relative newcomers, having been developed in 1995. It is a new generation of petunia that is wet weather tolerant (because of its smaller flowers) and have long bloom times.

As container plants they don’t need to be mixed with anything else, because they easily fill a container and can also be used as a focal point in the garden. At last year’s Open Garden, students from the Lifestyle College of Gardening mixed Easy Wave petunias with calibrachoa in rusty old wheelbarrows as a focal point.

Easy Waves work equally well as bedding plants. To form a dense edging, plant them 15cm apart. For pops of colour in a bed, space plants 30cm apart so that they can grow into larger mounds.

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In large gardens, mass petunias to form a drift or use them to soften natural rocky outcrops and arid gardens as a ground cover.

They combine well with other garden favourites. Varney created a yellow-themed display by mixing Easy Waves with celosia, gazanias, dahlias, alstroemeria Summer Breeze, bidens Eldoro Yellow Compact and the yellow Everyday lily.

Most of the calibrachoas on show were used for hanging baskets and containers because of their multitude of small flowers. They are also heat tolerant and need little care.

Conga is the most compact, Cabaret is an allrounder which grows into a full, rounded plant and MiniFamous is a semi-trailing plant with single or large, double flowers.

The new calibrachoa Mini Famous Pinktastic has a gorgeous double pink bloom on a semi-trailing plant with a spread of 25cm-38cm. Plants flower early and keep on flowering, even through winter in warmer areas.

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Growing tips

Wave petunias and calibrachoa do best in full sun or with plenty of morning sun. Plant them in well composted soil that drains well. If the garden soil is heavy mix in organics (compost, peanut shells) that raise the level of the beds for drainage.

Water thoroughly once a week (depending on soil and temperature) rather than a little every day. It is not harmful to let petunias dry out a little because this forces the plant to put down deeper roots and prevents water logging.

Because they flower non-stop, fertilise every two weeks with a granular fertiliser to keep up the plant’s strength. This will get the best performance from them.

Do not plant petunias in the same spot for two consecutive years, as they can be attacked by soil borne fungal diseases like Phytophtera, Pythium and Rhizoctonia.

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