Regal & Zonal pelargoniums are frequently known as geraniums and should not be confused with the genus geranium (cranesbill)
The types usually grown in the UK are tender evergreen plants suitable for greenhouse cultivation, house plants and summer bedding.
They are easy to propagate, easy to care for, and can thrive in the richest or poorest of soils, and do not seem to mind excessive wet or severe drought.
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Note; There is no particular 'best time' of the year for taking cuttings!
Many of the pelargonium family have no dormancy and grow for twelve months of the year.
However, success will depend on being able to supply good light and warm compost.
Cultivation;
On receipt of mail order plants, pot the plants singly in 100mm (4") pots using a good proprietary potting compost or John Innes No 2.
Grow on indoors at a temperature of 7º-10°C (45º-50°F), shading the plants from direct sunlight.
When the plants are about 150mm (6”) tall, pinch out the growing tip to encourage bushy growth.
Keep the plants just moist until they start to grow, then water more freely, giving a weak liquid feed every 10-14 days from May to September.
Use a high potash (low nitrogen) feed to promote flowers rather than leaves.
They flower continuously from late May to the first frost.
Note; The number of flowers is very much related to the length of sunshine they receive so ensure that they are in the sunniest of position, lack of light tends to make them grow tall and leggy as they reach towards the light.
Remove dead flower heads regularly to promote further flowering shoots to grow.
Week 1; January means the shortest day has passed and soon the plants will be starting into growth again.
Check foliage, remove any that is discoloured and collect up any leaves that may have fallen from the plants.
Week 4; Sow seed in trays/pots of seed compost and germinate them at 21°-24°C (70°-75°F).
It is advisable at this time to drench the seed compost with a fungicide to reduce the risk of disease.
Germination should take 5-7 days
Week 5; Now is a good time to take cuttings from ‘ivy leafed’ varieties. (Proceed as described in week 23)
You may find that your plants are looking decidedly gnarled and brown; they can soon be revived with fresh compost and feeding,
Note; your old plants may be showing brown scarring on the underside of the leaves, do not panic, this is not a disease, but a physiological disorder called oedema.
This often affects the older leaves of the ivy or hybrid ivy types and is caused by erratic watering.
If the plants have got rather dry and are then watered, the stomata on the back of the leaves cannot always cope, and they burst.
Afterwards they callous over, so what you see is like a scar.
Remove any unsightly looking leaves.
Week 10; Prick out the seedlings if they are large enough to handle into 75mm (3”) pots of potting compost.
Grow on at a temperature of 15°C (60°F)
Provide adequate moisture during this period, but be careful not to over water as this might cause botrytis to form.
It is preferable to water early in the day so that the plants have a chance to dry out a bit before nightfall.
Pinch out the tips of plants grown as bushes when about 150mm (6”) high.
Week 10-14; Prune established plants by cutting them back by a third to a half, and re-potting them into fresh moist potting compost.
Week 18> Subject to your local weather conditions one can now consider putting plants outdoors in baskets and containers when all fear of frost has passed.
Choose upright growing plants for the centre, and trailing ones for the edges of the tubs or baskets.
Dwarf varieties are a good choice for the middle of a hanging basket because they will bush out nicely, but not grow too tall.
The same applies to window boxes.
If using the same planters as the previous year remove the top 50mm (2”) of old spent compost ( all of the compost in the case of baskets and small containers)
Fill the void with new potting compost*
* Add 25% grit to this compost to improve the drainage around the root system.
Watering; Do not rely on the rain to supply the plants needs because even in the wettest summer, not enough rain will get into a tub or basket.
Feeding; Either put some slow release pellets or tablets in the compost when you plant up, or give a weak feed of a high potash formula (tomato feed) every time you water.
Week 23-35; Take tip cuttings.
As mentioned above there is no set time to take cuttings, but now is useful time for those people who do not have ideal propagation conditions e.g. a propagator.
The only problem you may find is obtaining cutting material i.e. non flowering shoots now that your plants are likely to be in full bloom.
If you find yourself in this position think about a month in advance and cut out the flowering shoots on your selected parent plants to allow new ‘cutting material’ to develop.
Select healthy tips of stems, and trim to just below a leaf joint to leave a cutting of about 70-100mm (3”-4”) long.
Take a cutting just above the ‘node’ (set of leaf joints).
Trim the cutting to just under the next set of leaves – take off the lower leaves, any flower buds and clean off any stipules (the flaky bits on the stems)
Note; Some people advocate leaving cuttings on bench to dry for 24-48 hours, this is optional.
The use of a hormone rooting powder/gel at this stage is also optional.
Similarly some people use a vitamin C tablet ( ascorbic acid) dissolved in an egg cupful of water as a rooting activator.
Insert cuttings round the rim of a pot filled with a well-drained compost, and place them in a warm, sunny position.
If you have a propagator or hot bed this would be ideal.
Do NOT cover with plastic bags or put the lid on the propagator – remember that geraniums will rot in a humid atmosphere.
When rooted pot the cuttings on as necessary.
Week 40> If whitefly has been a problem during the season now is a fine time to locate any eggs that may have been laid on the underside of plant leaves.
Examine the leaves and remove any that show any sign of ‘egg’ infestation rather than using the alternative option of spraying with an insecticide.
Sprays will only kill the adult aphids and have no effect at all on the egg or pupa stages of development.
Week 43>; Now is about the time to be considering moving plants into their winter quarters.
Pelargoniums are quite tender and need protection during the winter months.
Lift plants from bedding schemes, and dismantle your hanging baskets / containers by pulling out the pelargoniums then tap the plants out and break the roots apart gently, saving as much root as possible.
Pot them down into 150mm (6") pots and store them in a frost free greenhouse
Do not worry if some of the roots are broken off – they will renew once they have been potted up in fresh compost.
Don’t overwater whilst the plant is recovering from transplanting.
A guide to keeping your plants alive during winter:
Plants will not survive if stems are subjected to freezing temperatures.
Plants do not go into dormancy as such, so they will continue to transpire and so will need some moisture.
Keep the atmosphere dry, but not the roots, moist but not wet is the key.
Light is also very important during the short winter days.
Note; a plant a metre in from the window will receive 50% less light than one on the window cill
Throughout winter plants just need to be kept frost free, around 5 º C (41ºF).
If you only have a few plants newspaper or horticultural fleece are the best materials for insulating the plants on a cold night.
Bubble plastic is not good if it is left over the plants because it traps the damp, and this can be as damaging as frost.
The best heating for pelargoniums is an electric fan heater with a thermostat.
Its greatest advantage is; that it blows dry air around, where gas and paraffin on the other hand both add moisture to the atmosphere as they burn.
Ventilate as often as possible.
Geraniums do not like a humid atmosphere!
Take a few minutes each week to look at your plants and see if they are growing well.
Regularly turn the plants around to achieve an all round shape.
Week 48> Now is a good time to check over your stored pelargoniums.
Remove any dead leaves and flowers.
Check the plants for drying out, water them as required.
If you find that a lot of the lower leaves have turned yellow the cause might be one of several things e.g.
Maybe the plants have got too dry at the roots.
It might be that the plants are stored too close together, so that no light is getting to the bottom of the plant.
A third reason could be that somehow the plants have become waterlogged. (Leaking greenhouse/coldframe roof)
If any plant is getting a bit lop-sided, turning the plants regularly might help.
