Last November, I planted massed purple petunias for my mum. She loves them and keeps trying to decide which shade she likes best. But after months of hot summer sun, they have become straggly. The leaves have a dull white mould and although the flowers do their best to appear perky – it’s not a pretty sight.
Drastic action is required! First – cut them back. I look for some healthy growth near the roots, and cut off the rest. This hurts, because I am cutting off all the blooms, leaving only stumps behind. But the plants have established root systems so will recover quickly. I give them a spray of mould-kill and scatter a general fertiliser. Next, I fork over the bed, gently lifting the plants a little bit so that the compacted soil loosens, allowing water and feed to penetrate. Finally, I top up the mulch with fresh tanbark and water in well. It takes 2-3 weeks before the new blooms appear, but the plants are now refreshed and will flower well into autumn.
Hint: if they are planted in a warm, protected part of the garden, they may flower through winter, into next spring. This rescue method should be applied to all annuals – not just petunias. It is much more effective (and cheaper) than ripping them all out and buying new plants. Happy Gardening!