When To Plant Geraniums Outside In The UK

Pelargonium (Geranium)

Pelargoniums or more commonly known as geraniums are one of the most popular if not the most popular bedding plant in the UK.

They are just as popular across Europe and many other countries around the world, where they can be seen everywhere adorning flowerbeds, patios, and window boxes.

The Swiss have even taken things a step further and elected the geranium as their country’s national plant, and yet it is classed as an exotic plant in the European continent.

When To Plant Geraniums

I have always advised my customers not to plant out their geraniums until the end of May, hoping that the threat of a late frost has passed, in you live in colder parts of the UK you may have to wait a little longer to plant them outside.

Geraniums normally become available at wholesalers in the UK around Mother’s Day in March, but I would never sell them to the public that early.

They do fine as a house plant at that time of the year, but most customers want to buy geraniums for planting out in their gardens. It would feel like I had done the public a disservice if I sold them that early and they got hit by a frost and wiped out their plants.

I think the old saying “Ne’er cast a clout till May be out” has something to do with to with clothes. But I see it the same with all summer bedding plants, geraniums included.

For as long as I have worked in the industry the second bank holiday in May has been the traditional time when gardeners plant their summer plants outside (normally the Chelsea Flower Show is on the TV that week as well so it gets everyone in the mood for a spot of gardening).

Types Of Geraniums (Pelargoniums)

Zonal Geranium

Pelargonium (Geranium)

Zonal’s are the familiar bedding geraniums that you see planted in gardens. Zonal geraniums get their name from the zone of blue, purple or red colour that strips through the middle of their leaves, thus making it an easy way to distinguish a zonal.

They have rounded leaves and bear clusters of flowers on long stalks. Colours range from scarlet red, orange, white and pink.

Ivy Leaf Geranium

Ivy Leaf Pelargonium (Geranium)

Commonly know as trailing geraniums and they originate from the peltatum pelargonium. They have long stems of flowers that trail over from anywhere between 15 cms (6 inches) to 2 metres (6 feet) depending on what variety you have, making them very well suited to growing in hanging baskets or windows boxes.

They often have smooth and shiny leaves, and the colour range is very much the same as a zonal geranium.

Regal Pelargonium

Regal Pelargonium

Regal pelargoniums are the posh relative of the common geranium, which have large, often patterned flowers borne in few-flowered clusters. Their leaves are usually coarsely toothed and may be pleasantly scented.

They have some of the most colourful flowers in this genus of plants, truly everything from black to white.

Angel Pelargonium

Angel Pelargonium

Angel pelargoniums are the miniature versions of the regal pelargonium, with small round leaves and pansy or viola like flowers.

They always flower in abundance and can be grown as a pot plant or in a hanging basket. They can also be used outside as summer bedding either by themselves or for mixed planting.

Fancy Leaf Geranium

The fancy leaf geraniums has some of the most colourful foliage in the plant world, and they seem to be an endless combination of leave and flower colour.

They have been used for bedding-out in public gardens since the 19th century, and there are some quite old varieties that are that in existence, but there is some cause for concern as very few nurseries stock them today.

Scented Leaf Geranium

The scented-leaf geranium has attractive foliage and the perfume resembles other plants, including roses, lemon, lime, pineapple and peppermint.

They tend to have smaller flowers than some other hybrid geraniums and bloom in spring and early summer.

The scented-leaf geraniums come in all shapes and sizes making them an interesting group to grow in your garden.

Unique Geranium

Unique Pelargonium

A very similar variety to the scented leaf geranium but they have a more attractive flower in colour and form.

Many have been around since the 19th century when they were used as an early type of bedding plant.

Stellar Geranium

Stellar pelargonium

One of the newest introductions to the geranium group, stellar geraniums were bred as recently as the 1970s in Australia.

They have enchanting foliage and flowers making them quite different from any geranium that came before. The range of flower colours and shapes is many and various.

The flowering ability of a stellar geranium is quite astounding with some plants having as many as twenty blooms.

They also flower for an extended time often being the first to start flowering and the last to finish.

Even though they have a delicate appearance, this just disguises their true nature, as they are one of the toughest and most resilient geraniums there is.

How To Grow Geraniums

Planting Position

Geraniums can be grown in full sun in flower beds, containers or hanging baskets. Regal pelargoniums do prepare a little shade at some point in the day though.

If you are growing them under glass protect them from direct sunlight in the height of summer.

Soil Type

Geraniums will grow in any soil type but will benefit from alkaline or neutral soil.

Planting Tips

When growing geraniums in a container choose a multi-purpose compost with an added slow-release fertiliser.

Geraniums look amazing when planted with other summer bedding plants. If planted in good compost and kept well-watered (but not too well as geraniums can be killed with kindness) they will withstand being planted tightly with other tender plants.

Propagating Geraniums

Red Geranium

Cuttings can be taken from geraniums in late summer if preferred, or wait until a lull in the plant’s flowering period.

When taking cuttings from a geranium cut with a pair of sharp garden scissors just above a node, or a swollen part of the stem. Cutting here will encourage new growth on the donor plant.

On the new cutting make another cut just below a node, so that the length from the leafy tip to the node at the base is between 10 to 15cm (4 to 6 inches).

Pinch out any flowering buds that are forming and strip off all but the top two leaves with a clean knife.

Fill a plastic garden pot with cutting compost and firm the compost down. Water and insert the cutting into the compost by about 1cm.

Position the pot in a warm but not hot place that is light, and don’t forget to label the pot if you have taken cuttings from different varieties.


Zonal geraniums are only susceptible to pelargonium rust. This is a fungal disease that is often worse in wet UK summer or if the plants have been grown in a poorly ventilated space.

Rust is easily spotted, the underside of leaves display brown spots. Destroy plants that are covered in the brown spots or purchase a suitable fungicide.

Geranium Care

Water well in the height of summer and deadhead to encourage a second flourish of blooms.

Geraniums are more than often grown as a summer annual and are composted at the end of the season. If you have a frost-free place, then it is worth trying to keep them to overwinter.

To overwinter, lift plants that are in the garden or containers and put them into smaller pots (this should be done before the first frost).

Cut back plants back by about a third and place in a frost-free but bright position. Geraniums do not go into complete dormancy so keep watering lightly throughout the winter.

In spring feed and increase watering. Plant back out only when the danger of frost has passed.

A Brief History Of The Geranium

Pink Geranium

Geraniums contain more than 250 species in the wild consisting of annual, biennial, and perennial herbaceous plants that are mostly native to the tropical regions of southern Africa.

Many of the wild species have very little in common with varieties available to us in the UK. For example, some are bushy shrubs that grow up to a height of over 6 feet, while others grow as succulent stemmed perennials in hot, dry habitats.

Around 50 species grow in the area around Table Mountain in South Africa. Which is not far from where the geranium embarked on its maiden voyage from the Cape of Good Hope to Europe courtesy of the Dutch East India Company in the 17th century.

It is reported that in 1632 famous gardener and plant collector John Tradescant the elder was the first person to grow a geranium (pelargonium triste) in England after purchasing the plant from René Morin in Paris. It is believed that the plant came from India.

No is one is certain how the plant came to arrive so early in the 17th century, but back then to reach India you would have had to round the Cape of Good Hope so the pelargonium triste could have been collected there.

Pelargonium triste or more commonly night-scented pelargonium is an oddity in the pelargonium world with its dull colouring, subterranean habit, and nocturnal perfume; it is mainly growth now purely for its historical view. The showier geraniums reached the UK around 1690.

Thomas Jefferson the third U.S. president and author of the Declaration of Independence is credited for first shipping the plant from France to American in 1786.

For centuries geraniums would be grown from cuttings until in 1962 breeders at Pennsylvania State University developed the first commercially successful propagated geranium from seed, named Nittany Lion Red.

Four years later the Harris Seed Company would develop the very first F1 hybrid geranium from seed. In 1968 the PanAmerican Seed Company’s Carefree series went on to win the coveted All-America Selections (AAS) award.

The F1 hybrid wouldn’t be commercially available in the UK until the 1970s, until then we simply bought pot-grown zonal geraniums for planting out in late spring, and then took cuttings in late summer for new plants to put out next year. With the introduction of the F1 hybrid, geraniums could now be grown from seed.

A number of new varieties are developed every year and to keep up to date you will have to read the current catalogues if you want to keep up to date.

Today the cultivation and production of pelargoniums is a booming global business. The current pelargonium range encompasses over 500 different types, most of which can be traced back to just a few of the 280 known wild species.

In greenhouses in Ethiopia, Kenia, Mexico and Guatemala mother stock plants of modern pelargoniums are propagated in the sunny climate typical of these regions.

Every year millions of cuttings are harvested from these stock plants, which are then delivered by plane to the countries where they are further cultivated into market plants in commercial nurseries and garden centres.

Today some 500 million pelargoniums are sold every year in Europe alone.


I am not surprised by the figure of half a billion geraniums being sold in Europe every year, I believe it is the most popular selling plant here in the UK.

There are a few reasons why they are so popular:

I think they became the most popular bedding plant here in the UK in the mid-2000s when we were hit by a couple of hosepipe bans by the water companies. So the general public planted geraniums instead of their regular favourites because geraniums require less water.

Around the same time, we had a problem with busy lizzies here in the UK, whereby they were being wiped out by downy mildew, and busy lizzies had to have a rest for a few years. A lot of people in the industry thought begonias would take the place of busy lizzies while on their sabbatical, but I believe the public just bought even more geraniums.

And lastly, I think they are so popular because they are so low maintenance and can be left for a week or two while you go on your summer holiday.