The Geranium and Pelargonium Conundrum
Many gardeners, particularly in the UK and Europe, often refer to the popular, vibrant, and often trailing plants found in window boxes and hanging baskets as 'geraniums'. However, this common usage can be botanically misleading. The plants most people mean when they say 'geranium' are, in fact, Pelargoniums. True Geraniums, on the other hand, are a separate genus of plants, often referred to as 'Cranesbills', which have a distinct appearance and growth habit. This distinction is not merely semantic; it affects how you care for the plants, their hardiness, and their suitability for different garden environments.
- Pelargoniums are commonly misnamed 'geraniums'.
- True Geraniums are known as Cranesbills.
- The difference impacts plant care and identification.
- Botanical accuracy aids gardening success.
The confusion largely stems from historical naming conventions. When European botanists first encountered Pelargonium species from South Africa, they observed similarities to the European Geranium genus and placed them within it. Over time, as scientific classification evolved, Pelargonium was established as its own distinct genus. Yet, the common name 'geranium' stuck for the popular Pelargonium varieties, creating a widespread, albeit inaccurate, association. This article aims to clarify the true difference between geranium and pelargonium, helping you identify and cultivate these plants with greater confidence.
The core distinction lies in their botanical classification, leading to differences in their physical characteristics and how they behave in cultivation.
Why the Confusion Persists
The enduring confusion between these two plant genera is a testament to the power of common names in horticulture. For decades, nurseries, seed packets, and gardening books have labelled Pelargoniums as 'geraniums'. This widespread adoption means that many gardeners learn plant names through this common nomenclature, which then becomes deeply ingrained. When these gardeners encounter true Geraniums, they might be surprised by their different appearance, or they might simply continue to apply the familiar 'geranium' label. This creates a cycle where the misnomer is perpetuated across generations of plant enthusiasts and casual gardeners alike. It’s a classic case of a common name overriding botanical accuracy in everyday conversation and practice.
Understanding Botanical Classification
Botanical classification uses a hierarchical system to group organisms based on shared characteristics and evolutionary relationships. Both Geranium and Pelargonium belong to the Geraniaceae family, which is why they share some superficial resemblances and are often grouped together. However, within this family, they diverge into separate genera. This separation is based on significant morphological differences, particularly in their flower structure, leaf arrangement, and seed pods. A key visual cue is often the seed capsule; Geraniums produce a distinctive, long, slender beak-like structure that resembles a crane's bill (hence 'Cranesbill'), while Pelargonium seed pods are typically shorter and less prominent. This fundamental botanical divergence is the root of the difference between geranium and pelargonium.
Identifying True Geraniums (Cranesbills)
True Geraniums, commonly known as Cranesbills due to their distinctive seed pods, are a hardy and versatile group of plants. Unlike their Pelargonium cousins, most Geranium species are perennial and remarkably frost-tolerant, capable of surviving cold winters in the ground in many climates, including much of the UK. They typically form clumps of palmate or lobed leaves, often with attractive veining or a slight fragrance. The flowers, while varied in colour, often have a more delicate, star-like appearance with five petals, and they tend to be less showy and more understated than the large, often rounded blooms of many Pelargoniums. Their growth habit is generally mounding or spreading, making them excellent ground cover or border plants.
Key Characteristics of True Geraniums
- Hardiness: Generally perennial and frost-tolerant.
- Leaf Shape: Palmate, lobed, or divided, often with attractive patterns.
- Flower Structure: Five petals, often star-shaped, usually less flamboyant than Pelargoniums.
- Growth Habit: Mounding, spreading, or upright, suitable for ground cover and borders.
- Seed Pods: Distinctive 'crane's bill' shape.
These characteristics make true Geraniums a staple for perennial borders, rock gardens, and woodland settings. They are relatively low-maintenance, often thriving in a range of conditions from full sun to partial shade, depending on the species. Varieties like Geranium 'Rozanne' or Geranium sanguineum are popular for their long flowering periods and robust nature. They are also excellent companions for other plants, fitting seamlessly into mixed borders where they can complement flowering shrubs or perennials. While they don't offer the same instant 'wow' factor as some Pelargoniums, their enduring presence and resilience make them invaluable in garden design.
The most significant difference is their hardiness; true Geraniums are typically perennial garden plants, while most Pelargoniums are treated as annuals or overwintered indoors.
If you are unsure whether a plant is a true Geranium, check its hardiness rating. Hardy perennials are a strong indicator of the Geranium genus.
Common Geranium Varieties
Within the true Geranium genus, there is a wide array of species and cultivars, each with unique attributes. Geranium sanguineum, the Bloody Cranesbill, offers deeply cut foliage and magenta flowers, often blooming prolifically in sunny, well-drained spots. Geranium 'Rozanne', a hugely popular hybrid, is celebrated for its exceptionally long flowering season, producing abundant violet-blue flowers from late spring until the first frosts. Geranium macrorrhizum is known for its vigour and aromatic foliage, making it an excellent choice for suppressing weeds in difficult, shady areas. These examples showcase the diversity and adaptability of true Geraniums, proving they are far more than just a simple bedding plant.
Understanding Pelargoniums
Pelargoniums are the plants that most often come to mind when people think of bright, colourful, and often fragrant 'geraniums'. Originating primarily from South Africa, these plants are famous for their diverse forms, including upright, trailing, and ivy-leafed varieties, as well as their abundant, showy flowers. However, the key difference from true Geraniums is their lack of frost tolerance. Most Pelargoniums are tender perennials, meaning they cannot survive freezing temperatures and are best treated as annuals in cooler climates like the UK, or overwintered indoors to be replanted the following year. Their leaves are often scented, ranging from the classic 'geranium' scent to notes of mint, lemon, or even apple, adding another sensory dimension to their appeal.
Distinctive Features of Pelargoniums
- Hardiness: Tender perennials; typically grown as annuals or overwintered indoors.
- Leaf Shape: Often roundish, lobed, or fan-shaped, frequently with distinct zones or patterns; many are aromatic.
- Flower Structure: Typically larger, more rounded petals, often in vibrant shades of red, pink, white, orange, and purple; can be single or double.
- Growth Habit: Upright, trailing (ivy-leafed), or zonal varieties, ideal for containers, baskets, and bedding.
The visual appeal of Pelargoniums is undeniable. Their large, often clustered blooms provide a consistent splash of colour throughout the summer months, making them a popular choice for patios, balconies, and garden beds. The zonal pelargoniums, named for the distinctive coloured bands on their leaves, are particularly robust and widely cultivated. Ivy-leafed pelargoniums, with their trailing habit and glossy foliage, are perfect for hanging baskets and window boxes, cascading over the edges with masses of flowers. The variety of colours and forms available means there's a Pelargonium to suit almost any decorative need.
To encourage more blooms on Pelargoniums, regularly deadhead spent flowers and feed them with a balanced liquid fertiliser during the growing season.
Cultivating Pelargoniums
Successful cultivation of Pelargoniums hinges on providing them with the right conditions, primarily good drainage and ample sunlight. They thrive in well-drained soil and prefer a sunny position to produce their best blooms. Overwatering is a common pitfall, as their roots can be prone to rot in consistently damp conditions. When overwintering, it's essential to reduce watering significantly and ensure they are kept in a frost-free environment, such as a cool greenhouse or a bright windowsill indoors. Taking cuttings is a popular and effective way to propagate Pelargoniums, allowing gardeners to preserve favourite varieties and create new plants for the following year. This process is generally straightforward and can be done in late summer or early autumn before the main plant is brought indoors for winter.
Making the Right Choice for Your Garden
Deciding between true Geraniums and Pelargoniums depends entirely on your gardening goals and local climate. If you're seeking reliable, low-maintenance perennials that will return year after year, require minimal fuss, and can withstand winter frosts, then true Geraniums (Cranesbills) are your go-to. They are excellent for filling borders, acting as ground cover, or naturalising in more informal garden settings. Their hardiness makes them a sound investment for long-term garden structure and colour. Consider them for areas where you want established plants that require little seasonal replanting.
Choosing Based on Climate and Maintenance
- For Cold Climates/Perennial Beds: Opt for true Geraniums (Cranesbills).
- For Summer Colour/Containers/Baskets: Pelargoniums are ideal, grown as annuals or overwintered.
- Low Maintenance: True Geraniums generally require less seasonal effort.
- Winter Protection: Pelargoniums need to be brought indoors or replaced annually.
Conversely, if you desire vibrant, prolific summer blooms for containers, hanging baskets, or bedding schemes, and you are prepared to either treat them as annuals or provide winter protection, Pelargoniums are the perfect choice. Their intense colours and long flowering period offer immediate visual impact. Think of them for seasonal displays on patios, decks, or window boxes where their bright colours can be fully appreciated. While they demand more seasonal attention, the spectacular floral show they provide is often considered well worth the effort. For instance, if you're planting cosmos in pots or growing sunflowers, Pelargoniums can provide a complementary burst of colour.
Understanding the difference between geranium and pelargonium empowers you to select plants that will truly thrive in your specific garden environment.
Companion Planting Considerations
When planning your garden beds, knowing which plant is which can also inform your companion planting choices. True Geraniums, being hardy perennials, can be integrated with a wide range of other perennial plants, shrubs, and even some bulbs. They can serve as excellent companions for plants that might appreciate a bit of ground cover, such as roses or larger shrubs. For example, if you're considering where to plant sweet peas or how to plant petunia seeds, a perennial Geranium border might offer a stable, long-term planting scheme around them. Pelargoniums, often used in annual bedding schemes, can be paired with other summer-flowering annuals. They look fantastic alongside petunias, marigolds, or zinnias, creating a cohesive and colourful display that lasts for the entire summer season. Just remember that begonias, while often treated as annuals, can be perennial in warmer climates, and zinnias are also typically grown as annuals.