Beware Black Leg fungus - there's no known cure... GARDENING

Geraniums, or pelargoniums, were wonderful this summer because they enjoyed all that hot sun in July.If you are like us you will have some favourite varieties from which you would like to take cuttings.If so, this is the ideal time to get them to root.

Saturday, 21st September 2019, 7:00 am
Updated Saturday, 21st September 2019, 7:00 am

Cuttings taken at this time of year will root quickly and are far less likely to rot off at the base.

This disease is a fungal one called Black Leg. It sounds awful and it is. There is no cure.

Cuttings are taken off the parent plant carefully, using sharp secateurs.

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The cuts should be made just above a leaf joint, known as a node, as this will ensure fungi will not travel down the cut stem causing the parent plant to rot.

The cuttings to be propagated need to be about four to five inches long. All the leaves are removed by bending them down so they snap off the stem.

Only the top two leaves and the tip should remain and all the tiny green scales on the stems removed with a sharp knife. If these are not removed they often rot and cause the stem to die.

The most important cut is the final one which consists of cutting the base of the cutting.

This must be done with a very sharp knife or razor blade and should be about an eighth of an inch below the lowest node, making a sharp cut straight across the stem.

The compost needs to be very sandy. Any universal compost or John Innes seed compost may be used but make sure you add 50 per cent extra sharp sand or potting sand and mix really well.

Three cuttings are normally inserted around the edge of a five-inch diameter pot so the foliage doesn’t touch.

After you have filled the pots, scatter more sand over the surface so when the cuttings are inserted, sand will fall into the hole made by your dibber.

The cuttings must be firmly inserted.

When I was an apprentice our head gardener would take hold of a cutting and lift the pot off the bench. If the pot fell off you had to insert the cuttings all over again. The pots were watered after this test.

Pots of cuttings will root best if they are in a greenhouse covered with a sheet of newspaper, not in a plant propagator as they prefer not to be kept in a humid atmosphere. They should root in three weeks. Once this happens the tips are removed to ensure the cutting will be bushy and each cutting is planted into a three-inch diameter pot to over-winter in a frost-free greenhouse.

You may have noticed, no rooting powder has been mentioned. I normally tell people to use it if it makes them feel more confident!

When taking cuttings, have a look to see if there are any caterpillars. At this time of year the plants can be decimated. If there are lots of holes, there are lots of caterpillars. Wear latex gloves and give them a squeeze, the odour is awful but you throw the gloves away after the operation.


Buy colchicum bulbs for the grandchildren. Put one in an egg cup on their bedroom windowsill and a water lily-like flower will appear. Plant them in the garden. They will naturalise, producing blooms each autumn.