Understanding Geraniums: Perennial Herbs vs. Annual Bedding Plants
The straightforward answer to 'are geraniums annual or perennial plants' is nuanced. It depends on which 'geranium' you are referring to. Gardeners often use the term 'geranium' to describe two distinct groups of plants: the hardy, true Geraniums (often called cranesbills) which are reliably perennial, and the tender Pelargoniums, which are widely cultivated for their vibrant blooms and are usually grown as annuals in cooler climates.
This distinction is crucial for successful gardening. True Geraniums are hardy herbaceous perennials, meaning they die back to the ground in winter but their roots survive and send up new growth each spring. They are prized for their often deeply lobed leaves and star-shaped flowers, and many varieties offer attractive foliage colours and shapes. Pelargoniums, on the other hand, are native to warmer regions and are not frost-tolerant. While they can be perennial in USDA zones 9-11, most gardeners in temperate climates treat them as annual bedding plants, enjoying their prolific summer displays before the first frost claims them.
- True Geraniums (cranesbills) are hardy perennials.
- Pelargoniums, commonly called geraniums, are often grown as annuals.
- Climate dictates whether Pelargoniums can overwinter.
- Understanding the difference impacts care and seasonal planning.
The confusion arises because Pelargoniums were once classified under the Geranium genus. Although scientifically reclassified, the common name 'geranium' stuck for many popular Pelargonium varieties. This leads to a situation where gardeners might buy a plant labelled 'geranium' expecting it to behave like a hardy perennial, only to find it dies back completely after the first frost.
Identifying True Geraniums (Cranesbills)
If you're looking for plants that will reliably return year after year, focus on those labelled as 'Hardy Geranium' or belonging to the Geranium genus. These plants are robust and adaptable. They offer a wide range of flower colours, from delicate pinks and whites to deep blues and purples, and many have attractive, often aromatic, foliage. Varieties like Geranium 'Rozanne' are renowned for their exceptionally long flowering periods, often blooming from late spring until the first hard frosts. Others, such as Geranium cinereum, offer silvery foliage and dainty flowers, perfect for rock gardens or borders. Their cultural needs are generally straightforward: most prefer well-drained soil and a position in sun to partial shade.
Recognising Pelargoniums (Bedding Geraniums)
Pelargoniums, the plants most people picture when they think of 'geraniums' for summer hanging baskets and containers, are a different story. These include the zonal geraniums (Pelargonium x hortorum) with their distinctive 'zones' of colour on the leaves, the ivy-leaf geraniums (Pelargonium peltatum) with trailing stems ideal for baskets, and the regal or Martha Washington geraniums (Pelargonium x domesticum) with their large, showy blooms. These plants thrive in heat and sun but are susceptible to frost. While they can be overwintered indoors in a bright, cool location and repotted in spring, this requires specific care and often results in a less vigorous plant initially compared to buying new stock each year. For most gardeners, treating them as annuals simplifies planting and ensures the best display throughout the summer growing season.
Why the Confusion: Taxonomy and Common Names
The common plant name 'geranium' is a prime example of how taxonomy and common usage can diverge, creating confusion for gardeners. Historically, many plants now classified as Pelargonium were grouped with Geraniums. As botanical understanding evolved, these plants were reclassified into separate genera, but the familiar, common names often persisted in horticulture and among the general public.
This historical overlap means that when you visit a garden centre or browse plant catalogues, a plant labelled 'geranium' is very likely to be a Pelargonium. These are the bedding plants that provide prolific, bright colours in summer, featuring large, often rounded or lobed flowers and distinctive leaf markings. They are bred for their showy flowers and fast growth in warm conditions, making them ideal for annual displays in pots, window boxes, and borders. Their value lies in their spectacular summer performance rather than their winter hardiness.
The common name 'geranium' typically refers to Pelargoniums, which are usually grown as annuals in temperate climates, while true Geraniums (cranesbills) are hardy perennials.
True Geraniums, often called cranesbills due to the shape of their seed pods resembling a crane's beak, are a different group entirely. These are robust, herbaceous perennials that are fully hardy in most garden situations. They offer a more understated charm, with often delicate, intricate flowers and attractive, deeply cut foliage. Their appeal is in their reliability, their tolerance of a wider range of conditions, and their ability to provide structure and colour to perennial borders year after year. They are the plants that will naturally reappear from their roots each spring.
The Role of Climate in Perenniality
The classification of a plant as annual or perennial also heavily depends on your local climate. For Pelargoniums, the determining factor is frost. In regions with mild winters, such as parts of the southern UK, the Mediterranean, or California, Pelargoniums may well survive outdoors year-round and behave as perennials. They might drop their leaves and stop flowering during the cooler months but will often re-emerge with the spring warmth. However, in areas that experience hard frosts, any Pelargonium left outside will be killed. This is why they are predominantly sold and treated as annuals in climates with distinct, cold winters.
For hardy Geraniums, the situation is reversed. They are adapted to withstand cold winters and are reliably perennial across most of the UK and similar temperate zones. They enter dormancy in autumn, with foliage dying back, but their root systems are perfectly capable of enduring freezing temperatures. Their perennial nature means they become established over time, often improving in vigour and spread with each passing year, making them a sustainable and low-maintenance choice for long-term garden design.
Ensure you read plant labels carefully when purchasing. Look for 'Hardy Geranium' or 'Cranesbill' if you want a perennial that returns annually. If the label states 'Pelargonium', treat it as an annual unless you are in a very mild climate or prepared to overwinter it indoors.
Cultivating Geraniums: Annuals vs. Perennials
Understanding whether you're growing an annual Pelargonium or a perennial Geranium dictates a significant difference in how you care for them and what you can expect from them season after season.
Caring for Annual Geraniums (Pelargoniums)
Pelargoniums are the stars of summer bedding. To get the best from them, treat them as thirsty, hungry plants during their growing season. They thrive in full sun and require regular watering, especially when grown in containers, which can dry out quickly. Avoid waterlogging, however, as this can lead to root rot.
Feeding and Deadheading
Regular feeding is key to sustained flowering. Use a balanced liquid fertiliser every two to four weeks, or incorporate a slow-release fertiliser into the potting compost at planting time. Deadheading – removing spent flowers – is also crucial. Pinching off faded blooms encourages the plant to produce more flowers rather than setting seed. This simple act dramatically extends the blooming period and keeps the plants looking tidy.
Overwintering Pelargoniums
If you wish to try and keep Pelargoniums through winter, the process typically involves bringing them indoors before the first frost. Trim them back by about half, remove any dead or diseased leaves, and repot them into fresh compost if they are in pots. Keep them in a bright, cool location (around 7-10°C) and water sparingly – just enough to prevent the soil from drying out completely. In spring, once the risk of frost has passed and they show signs of new growth, they can be repotted, pruned more heavily, and gradually acclimatised back to outdoor conditions.
Caring for Perennial Geraniums (Cranesbills)
Hardy Geraniums are far less demanding. Once established, they are remarkably drought-tolerant and generally require little feeding. They are best planted in well-drained soil, with most varieties preferring sun or partial shade. Their main care requirement revolves around maintaining their shape and encouraging reblooming.
Pruning and Maintenance
Many hardy Geraniums benefit from a 'Chelsea chop' or a mid-season prune. After their first flush of flowers, cutting the plants back by about a third to a half can encourage a bushier habit and a second wave of blooms. This is particularly effective for long-flowering varieties. For Geraniums that tend to spread vigorously, like Geranium psilostemon, occasional division in spring or autumn is advisable to manage their size and rejuvenate them. Removing dead or dying foliage in autumn helps to prevent disease overwintering.
Division and Propagation
Perennial Geraniums are easily propagated by division. In early spring or autumn, lift the plant and carefully split the root ball into smaller sections, each with roots and shoots. These divisions can be replanted directly into the garden or pots. This process not only provides new plants but also helps to maintain the health and vigour of the parent plant.
Deadhead annual geraniums diligently to prolong their flowering season. For perennial geraniums, a mid-season cut-back can encourage a second flush of blooms and a neater appearance.
Choosing the Right Geranium for Your Garden
When deciding whether to plant annuals or perennials, consider your garden's aesthetic goals, your climate, and the level of maintenance you're prepared to undertake. Both types of 'geranium' offer unique benefits.
For Instant, Showy Colour (Annuals)
If you desire immediate, vibrant, and continuous colour throughout the summer months, annual Pelargoniums are an excellent choice. They are perfect for filling hanging baskets, window boxes, containers, and borders where a splash of intense colour is needed for a single season. Their wide range of colours – from bright reds and pinks to softer pastels and whites – allows for extensive design possibilities. They also pair well with other summer bedding plants like petunias, marigolds, and lobelia, creating classic, eye-catching displays. For gardeners who enjoy refreshing their displays annually or live in climates unsuitable for overwintering, annuals provide a reliable and spectacular performance.
For Reliable, Long-Term Groundcover and Borders (Perennials)
Hardy Geraniums are the backbone of many perennial borders, offering dependable colour and foliage interest for years. They are superb for groundcover, suppressing weeds once established, and for edging pathways or filling spaces between shrubs. Their naturalistic habit and wide variety of forms make them suitable for cottage gardens, rock gardens, woodland edges, and modern prairie-style planting. Varieties like Geranium sanguineum produce masses of delicate, often magenta flowers over a long period, while others, such as Geranium wallichianum, have beautiful trailing habits and intricate flower patterns. Their resilience means that once planted, they require minimal intervention, providing a sustainable and low-maintenance source of garden beauty.
When choosing between the two, ask yourself:
- Do I want a plant that flowers profusely for one summer, or one that returns year after year?
- Is my climate mild enough to potentially overwinter Pelargoniums, or do I prefer the certainty of hardy perennials?
- Am I looking for bold, uniform colour blocks, or a more naturalistic, textured planting scheme?
Companion Planting Considerations
Whether you choose annuals or perennials, understanding companion planting can enhance your garden's health and aesthetics. For sunny spots where you might plant annual geraniums (Pelargoniums), consider pairing them with plants that have similar sun and water needs. Trailing geraniums in baskets can be complemented by upright annuals like snapdragons or taller bedding plants. If you are planting hardy geraniums in borders, they can serve as excellent companions for shrubs, roses, and other perennials. For example, a vigorous Geranium 'Rozanne' can weave through the base of a rose bush, offering continuous colour. Hardy Geraniums can also complement plants like salvias, campanulas, and ornamental grasses, creating layered planting schemes that provide interest throughout the seasons.
For example, if you are growing cosmos in pots, annual geraniums can provide a contrasting texture and colour. If you're considering where to plant sweet peas, hardy geraniums could offer a complementary groundcover in the same sunny bed. The key is to match their general cultural requirements for sun, soil, and moisture.
The fundamental difference lies in their life cycle and hardiness. True Geraniums are perennial, designed to survive and thrive across multiple seasons, often for many years. Pelargoniums, while capable of living for several years in ideal, frost-free conditions, are typically cultivated and perform best as annuals in most garden environments, prized for their single season of spectacular bloom. Both have their place, contributing different qualities to a garden landscape.
Frequently Asked Questions About Geraniums
The distinction between annual and perennial geraniums often leads to specific questions from gardeners looking to make the most of these popular plants.
Are all geraniums perennial?
No, not all plants commonly called 'geraniums' are perennial. The group known as Pelargoniums, which includes many popular bedding plants for containers and borders, are tender and usually treated as annuals in cooler climates as they cannot survive frost. True Geraniums, often referred to as cranesbills, are reliably perennial and will return year after year.
How do I know if my geranium is annual or perennial?
Check the plant label. If it says 'Pelargonium' or specifies it's for bedding or containers and isn't described as hardy, it's likely an annual. If it's labelled 'Hardy Geranium', 'Cranesbill', or gives a botanical name from the Geranium genus and states it's perennial, then it is hardy. Observing its growth habit and foliage can also offer clues, but the label is the most definitive source.
Can I overwinter geraniums outside?
Whether you can overwinter geraniums outside depends entirely on your climate and the type of geranium. Tender Pelargoniums will not survive a frost and must be brought indoors in colder regions. Hardy Geraniums (cranesbills) are specifically bred to tolerate freezing temperatures and will naturally die back to the ground in winter, regrowing in spring. You can overwinter Pelargoniums indoors in a cool, bright spot, but this requires effort and they may not perform as vigorously in the following season.