Geranium and Pelargoniums

There are over 300 species of Geraniacaea. The best way to distinguish between Geraniums and Pelargoniums is the shape of the flowers and the colour of the leaves.

Pelargoniums have asymmetrical arrangements - 3 upper and 2 larger lower petals. They can be single or double. The leaves are lobed with colour in the leaves.

Growing

Pelargoniums are best treated as biennials and should be pruned regularly as they can get very woody. Use the prunings for cuttings.

Varieties include:

  • Zonals – rounded leaves distinctively marked with a darker zone.

  • Ivy leafed – trailing plants that can be trained on a trellis, from hanging baskets, down a retainer wall or used as a ground cover. (This variety will grow under iron-bark trees with a little help from mulch and liquid fertiliser.)

  • Herb/scented leaf – have beautiful leaves with various scents: lemon, peppermint, nutmeg, spice, or rose, etc. They are often used in the perfume industry.

Geraniums, or Crane’s Bill, have circular (symmetrical) flower heads at the crown of the plant. The leaves are deeply dissected with no colour. These originated in the cooler climates of Europe and Asia. They have a low growing mound shape and come in a variety of colours.

Problems

  • Pests – caterpillars, aphis and white mite can be treated if detected early.

  • Rust – shows up as black on top of the leaves usually from watering on their leaves.

  • Bacterial leaf spot – is caused by watering the leaves and poorly drained soil.

  • Stem rot, leaf curl virus and mosaic virus

  • – these are hard to cure. The signs for stem rot are obvious as the name says. The two viruses show up as leaves curling in or going yellow. The best advice is to get rid of the plant (roots and all). Put in a plastic bag and place in your NORMAL rubbish bin. Never put diseased plants in for recycling. That only spreads the disease to other areas and other gardens.

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