When you receive young Pelergonium plants by post they need potting into a good quality loam based compost, a John Innes No. 2 is ideal and a good peat based compost mixed in equal parts. Use a 9cm pot for most types except Angels and Miniature varieties, these need some root restriction so a smaller pot is best 6 or 8cm. The care of Zonal Pelargoniums, Scented leaf and Species, and Ornamental (Fancy Leaf ) varieties are all similar in treatment. The compost should be a good open texture with loam and added grit. Water immediately after potting. Place the young plants in good light. Pinch the lead out to encourage side shoots to form. Water as necessary, but do be careful not to keep your plant too wet. In spring and summer the frequency will increase to daily watering preferably evenings so that the plants retain the moisture for a longer period.

Growing in Peat

Some people prefer to grow in a peat based compost, which is fine. Be aware that a loam based compost will need less volume of water, particularly during the winter months and during poor weather conditions. Plants should be placed in good light, with plenty of air round them. A slatted bench where excess water can drain away is ideal, but a window-sill is a good position where the young plant can be nurtured until reaching maturity.

Feeding Pelargoniums

About a month later the plant will be ready to pot on into a final pot two sizes larger, between potting there will be no need to add fertilisers as there will be enough in the potting mixture to last. Overfeeding will lead to leaves like cabbages. As soon as the buds start to form, liquid feeding can commence. Use a high potash feed to encourage flowers and improve colour. Once a week is quite enough unless you have your plants in a tub or hanging basket, in which case you should feed twice a week or more using a weakened strength in the height of summer.

Watering Pelargoniums

Autumn care Plants which have been outside should be lifted and all poor foliage removed. Pot into good compost and prune hard, and dab sulphur powder on the wounds to dry them, and prevent infection. It is important where you cut the stem, just above the leaf node, where the leaf joins the stem, within 1mm. To prevent die back. Use a very sharp craft knife, or scalpel and wash in a dilute disinfectant or bleach to prevent cross infection between varieties. Water Pelargoniums sparingly throughout the winter. Always water early in the morning in winter as this is when your plant is the most active. The plant will need as much natural light as possible and a temperature of not less than 4° Celsius to keep it alive. Open the windows, weather permitting, as good ventilation is essential. Cut back quite severely, in September or early October, dust the wounds with Sulphur powder to prevent die back. Root prune and pot into as small a pot as possible to cut down on water retention during the winter months. A plant which has happily flowered in a 13cm pot will transfer into a 9cm pot for the winter months.

Regal Pelargoniums

Regal Pelargoniums do not require as much cutting back and require a slightly higher winter temperature. They prefer a clay pot, and like plenty of calcium, so hard water is ideal for watering rather than rain water which will be softer. Never allow the plant to dry out completely as the roots will seal and blackleg will creep up the stem and the plant will die. Remove dead flowers frequently and feed regularly with high potash so that they will perform as well as your Zonals.

Miniature Pelargoniums

Miniature geraniums will prefer to stay in a small pot, and therefore require more liquid feeding, a weak solution regularly of general fertiliser 1:1:1 and changing to high potash in summer. They will not require any cutting back and will flower during the winter as a pot plant, on a sunny window sill or in a conservatory.

Pests

Pests which may affect Pelargoniums include the usual greenhouse types- white fly, aphids, a regular spray programme as a deterrent is recommended. If you prefer to use an organic control there is a range of soap based products which are safe with children and animals. Laboratories offer a range of preditors which will help with a biological control. We recommend - the 'Bug Gun'® or Sybol®Extra which contains bifenthrin, the best treatment for whitefly, aphid, and mites.

For vine weevil Provado®™ and Armillatox®™are both recommended as a drench. The weevil lays its eggs in the compost and the emerging larvae devour the roots. Hygiene is the greatest deterrent to pest and disease, so regular cleaning of dead material is recommended. Always spray early in the morning, choosing a bright day so that foliage does not remain wet longer than necessary.

Mealy bug is a small white mite which lies in the soil. A bluish white deposit is left on the sides of the pot and the pest is visible to the naked eye in the roots down the sides of the pot when removed. Scairid fly, a small black fly rather similar to a fruit fly can be seen round the pots where there are moist conditions. They are usually where peat is the main type of compost used. The appropriate treatment is drench with Armillatox®™ or Provado®™ .

Damp air, causes lots of problems, rust, botrytis. Open the door when there is no frost, even vent occasionally, weather permitting - but don't forget to close everything down early in the afternoon.Treat with Nimrod T® which will help as a double acting systemic fungicide. Used regularly this prevents and controls mildew and rust.

Some growers just take cuttings and do not house the old plants over winter but second year grown plants make better displays. When the mother plant has finished flowering in October, shake the soil from the roots and cram into a much smaller pot. On a bright day, I wash the root system and then put the plant into a small pot. The top growth is pruned hard and all old foliage removed to expose bare stems. Within two weeks new young shoots will be seen on the old stems. As the new leaf develops I sometimes remove them as they make a canopy and prevent more light reaching the stems. This way I get more shoots forming and soon have plant which will bear many branches and be short jointed. Compare this plant with a young plant and you will see how the exhibition winners get their plants to such perfection. A good reason for reducing the pot size in autumn is that there will be less risk of over-watering during the dormant part of the year. More Pelargoniums are lost because of over watering, over enthusiasm of the TLC (Tender Loving Care). Only water on bright days so that excess will soon evaporate. During the winter months, water in the morning, this reduces botrytis. If low temperatures are maintained then probably once a month will suffice, but if we get a lot of sunny weather, the temperature of the glasshouse will rise considerably and plants may dry our before you know it. To illustrate the amount of water, in the summer I would saturate the pot till water is seen coming out of the base, or untill water is left standing in the saucer (Which is then removed). In the winter I barely give a teacup of water per plant. Just enough to keep the roots growing. Exhibition plants get different treatment because they are grown with more heat. Fans to pull air through are a good investment.

Over winter plant protection

Protect the plants using bubble plastic sheeting pinned to the greenhouse, particularly on the lower portions, leaving as much light as possible, but over the Christmas period I would even cover the roof as this is where the heat escapes. Use fleece to cover plants, which allow the plants to breathe when excessively low temperatures are expected. Your heater may not cope with the extremes of low temperatures. If a really cold spell develops, I leave the glasshouse without opening the door at all until the weather eases. Never use polythene or plastic sheeting over the plants, as this will turn the plants into compost. Special plants, which are very precious, should be removed into a spare room in the house, even the kitchen windowsill. These suggestions are tried by many growers who do not want to pay huge heating costs but want to keep as many plants as possible for the following year. Finally, when cutting back old plants, use very sharp secateurs, other wise you will mash the stems and then the plant will be at risk of infection. Dip the shears in dilute bleach between varieties so that any virus cannot be transferred, and then dab the wound with sulphur powder to dry the tip, and prevent stem rot.

I hope these notes will be helpful for those of you who are new to growing my favourite plant – The Pelargonium

Author

  Mary Spink author of   "The Potted Guide to Pelargoniums"