Pelargonium


 

Regal and Zonal pelargoniums are often referred to as as Geraniums, however they should not be confused with the genus Geranium (Cranesbill)


Many types / varieties are often seen growing outdoors but are not really 'hardy' enough to remain outdoors all the year round in the UK.

Because of this, it is best to treat them as half hardy perennials.

Cranesbill

The most common types grown in the UK are tender evergreen plants which are usually best suited for greenhouse cultivation, house plants and summer bedding, although most of these types can be grown outdoors in the summer months, and returned to a frost free environment during the colder months.


Pelargonium are usually defined in groups, for example:


Regal:


These are evergreen perennials with leaves sometimes rounded, lobed or partially toothed.

The flowers are generally single blooms although occasionally double varieties are available from specialist suppliers.

They come in various self and / or bicoloured varieties ranging from pure white to very dark purples which in certain light conditions can appear to be black.


Angel:


These are often derived from the species P. crispum and are quite similar to regals, but are usually more compact and bushy.


Ivy-leaved:


This group are trailing evergreen perennials with fleshy leaves and single or double flowers.

Because of this attribute they are often displayed in wall / hanging baskets and containers.



Zonal:


These are mainly derived from P. inquinans and P. zonale, and tend to be upright, bushy, succulent-stemmed perennials.

Some varieties have attractive (zonal) foliage and sport an abundance of single or double flowers.

They are often seen in bedding displays in public parks and leisure areas.


Scented-leaved:


These are similar to 'Zonals'and are mainly cultivated for their scented and often variegated leaves.


Varieties:

Within these groups there are literally hundreds of varieties many of which are grown by enthusiasts for exhibition purposes, and by others simply because they they require little aftercare.


Black Knight
Captain Starlight
Clorinda
Dainty Maid

Fairy Berry
Hazel
Honeywood Lindy
Imperial Butterfly

Lillian Pottinger
Pero Munster
Peter's Choice
Prince of Orange-Lavender

Rembrandt
Sancho Panza
Spring Park
Paintbox series - seedling

Paintbox series - seedling
Paintbox series - seedling
Paintbox series - seedling
Paintbox series - seedling

Paintbox series - seedling
Paintbox series - seedling
Paintbox series - seedling
Paintbox series - seedling

Attributes:


Most varieties are relatively easy to propagate either from seed or cuttings.

They can thrive in either the richest or poorest of soils, and do not seem to mind excessive wet or severe drought.

In terms of propagation there is no particular 'best time' of the year for taking cuttings, as many of the pelargonium family have no dormancy and grow for twelve months* of the year.

*Success will depend on being able to supply good light and warm compost during the winter months.


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 the plants 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.

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, if so, they can soon be revived with fresh compost and feeding.

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 disorder often affects the older leaves of the ivy or hybrid ivy types and is usually caused by erratic watering.

If the plants have been allowed to get rather dry, then you may find that after watering the stomata on the back of the leaves can't cope and they burst.

Afterwards the affected area callouses over leaving a scar. If the leaves become rather unsightly then it is best just to remove them.


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.


Seeds Germinated
Pricked out Seedlings
Seedlings progressing

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, and not grow too tall.

The same applies to window boxes.


If using the same large planter/s 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, the umberella affect of the leaves may not allow sufficient moisture to get into the compost in the 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.

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.(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)

When taking cuttings there are a number of optional things you can do prior to inserting the cuttings into the compost for example you could:

Leave the cuttings on the bench to dry for 24-48 hours .

Use a hormone rooting powder/gel .

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 often rot in an atmosphere that is too humid.

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 their planted positions, gently break the roots apart saving as much root as possible.

Pot them up into 100-150mm (4"-6") pots and store them in a frost free greenhouse.

Re- Potted / Tidied up Plants

Do not worry if some of the roots are broken off – they will renew once they have been potted up in fresh compost.

Take care to not overwater whilst the plant is recovering from transplanting.


Over wintering plants


Pelargoniums do not go into dormancy as such, they will continue to transpire meaning that they will require some moisture during the storing period.

Do this by keeping the atmosphere dry, and the roots moist, but not wet.

Pelargoniums do not like a humid atmosphere!


Light is also very important during the short winter days, for example; a plant placed a metre in from the window will receive 50% less light than one on the window cill.


Throughout the winter months, plants just need to be kept frost free, around 5ºC (41ºF).

Plants will not survive if stems are subjected to freezing temperatures.

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 can trap the damp, and this can be as damaging as frost.


The best type heating for pelargoniums is a thermostatically controlled electric fan heater.

This will keep the surrounding atmosphere buoyant and at the desired temperature. whereas gas and paraffin on the other hand tend to add moisture to the atmosphere as they burn.

If using any of the latter two options ventilate the area as often as possible.


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 plant/s regularly might help.


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