Architectural Plants for Pots

What are Architectural Plants?

Architectural plants are plants that have distinctive, bold features and shapes, which make them stand out in a garden or landscape. These features can include unique forms, strong linear structures, eye-catching foliage, or striking textures. Often used as focal points, architectural plants can be the backbone of garden design, providing structure and interest throughout the year. They’re particularly popular in modern and contemporary garden designs due to their ability to create drama and define spaces.

Some key characteristics of architectural plants include:

1.  Distinctive Forms: Many architectural plants have a strong shape, whether it’s the spherical shape of a topiary box or the tall, upright form of bamboo.

2.  Bold Foliage: Plants with large, unusual, or textured leaves, like the gunnera or palms, often fall into this category.

3.  Repetitive Patterns: The repeated patterns of certain plants, like the regular segmentation of horsetail (Equisetum) or the fronds of a fern, can make them architectural.

4.  Strong Lines and Silhouettes: Plants that have a pronounced outline or silhouette, such as the sharp edges of an agave or the towering presence of a yucca, are often considered architectural.

5.  Year-round Interest: Many architectural plants retain their structure throughout multiple seasons, offering interest even in winter when other plants have died back or become dormant.

Below is a guide to the best architectural plants suitable for pots.

1. Cordyline Australis, commonly known as the cabbage tree or cabbage-palm, is a distinctive and resilient plant native to New Zealand. It’s a popular choice for gardeners and landscape architects looking to add a dramatic and architectural element to their designs. With its bold silhouette and exotic appearance, Cordyline australis brings both vertical interest and a tropical flair to temperate gardens.

Characteristics

Cordyline australis can reach up to 20 metres in height, though typically it stands at about 10 metres when mature. It features a stout trunk and a graceful array of long, sword-shaped leaves, which cascade from the top in a palm-like manner. The leaves are a rich, dark green, though some cultivated varieties may have leaves in shades of red, yellow, or variegated colours.

Growth and Care

This plant thrives in a range of conditions but prefers well-drained soil and a sunny position, although it can also tolerate partial shade. It’s remarkably drought-resistant once established, making it an ideal choice for gardeners seeking low-maintenance but striking garden features. Cordyline australis is hardy and can withstand temperatures slightly below freezing, but younger plants and some of the more colourful cultivars might require protection from frost.

Uses in Landscape Design

•   Vertical Accent: Its upright form makes it an excellent choice for adding structure and height to the garden.
•   Container Planting: Smaller specimens can be grown in containers, making them suitable for patios and urban balconies.
•   Group Plantings: Planted in groups, they can create a dense, tropical effect, suitable for screening views or creating windbreaks.
•   Mixed Borders: Its foliage contrasts beautifully with rounded or softer plant shapes, enhancing the overall texture and form variance in gardens.

Cultivation and Varieties

Several cultivars of Cordyline australis have been developed to enhance certain features like leaf colour. Varieties such as ‘Torbay Dazzler’ with its striped green and cream leaves and ‘Red Star’ with deep burgundy leaves are particularly popular for their vivid colours and can add a splash of brightness to any garden setting.

Maintenance

Cordyline requires minimal upkeep. It might need occasional watering during extremely dry periods and benefits from a feed with a general-purpose fertiliser in spring. Older leaves naturally die off and can be stripped to keep the plant looking tidy.

Propagation

Propagation is generally by seed or by taking offsets from the base of the plant. These methods allow gardeners to produce new plants economically.

2. Agave Plants, with their bold, sculptural forms, are excellent choices for adding architectural interest to gardens, especially in cooler climates like the UK, where they are best grown in pots to manage their exposure to harsh weather.

Characteristics

Agave species are known for their rosette of thick, fleshy leaves, which can vary greatly in size, colour, and margin spines depending on the species. The leaves often have a waxy or powdery coating, which helps them resist drought. The most common colour is a deep green, although some species feature blue, grey, yellow, or variegated leaves.

Growth and Care

Agaves thrive in well-drained soil and should be placed in a position that receives full sun for the majority of the day. They are ideally suited to container growing in the UK, as this allows for easy movement indoors or under shelter during cold, wet winters. Containers also restrict their growth to a manageable size, making them easier to integrate into smaller spaces or grouped displays.

Uses in Landscape Design

•   Focal Points: Their dramatic form makes agaves perfect as focal points in garden design, whether positioned prominently on a patio or balcony.
•   Modern Gardens: Agaves fit well in modern or minimalist garden designs due to their clean lines and striking shapes.
•   Gravel Gardens: They are suitable for gravel gardens often seen in drought-tolerant landscaping.
•   Companion Planting: Agaves can be paired with other drought-resistant plants like sedums or smaller grasses that complement their rugged appearance without competing for attention.

Varieties Suitable for the UK

Some agaves are more suited to the UK climate, particularly smaller varieties that cope better with the cooler temperatures and can be easily sheltered. Examples include:

•   Agave parryi: Known for its compact form and silver-blue leaves, it’s hardier against cold.
•   Agave victoriae-reginae: Noted for its striking, compact form and smooth, patterned leaves.
•   Agave filifera: Features green leaves with white filaments, smaller in size, ideal for pots.

Maintenance

Agaves require little maintenance. They do not need frequent watering, making them perfect for a low-maintenance garden. Feeding is minimal, requiring only a light application of fertiliser in the growing season. It’s important to ensure that the pots have good drainage to prevent root rot.

Overwintering

In the UK, most agaves will need protection from wet and freezing weather. They should be moved to a well-ventilated, frost-free place during winter. For those left outdoors, it’s crucial to provide some form of cover or raised bed to ensure they are kept dry.

Propagation

Agaves can be propagated from offsets, which are small clones that grow around the base of the parent plant. This is an economical way to expand or renew your garden’s agave population.

3. Phormium (New Zealand Flax), known for its striking foliage and architectural form, is an excellent choice for gardeners looking to introduce a bold, sculptural element into their UK garden, particularly when grown in pots.

Characteristics

New Zealand Flax features large, sword-shaped leaves that fan out from a central base, creating an impressive display of form and colour. The leaves can vary significantly in colour, from deep greens to bronze, and striking variegations including yellows, reds, and pinks. Phormium can reach several feet in height and spread, making it a commanding presence in any garden setting.

Growth and Care

Phormiums are surprisingly hardy given their exotic appearance. They thrive in full sun to partial shade and prefer well-drained soil, making them well-suited to container growing in the UK. Pots also help contain their growth, as they can become quite large and potentially invasive if not managed properly.

Uses in Landscaping

•   Architectural Impact: With their upright, bold leaves, New Zealand Flax plants are perfect for adding architectural interest to a garden or patio.
•   Container Gardening: Ideal for large containers, they can be used as standalone features or combined with other plants to create varied heights and textures.
•   Coastal Themes: Their tolerance for wind and salt spray makes them excellent choices for coastal gardens.
•   Mixed Borders: Phormiums can be incorporated into perennial borders to provide a year-round structural backbone.

Varieties Suitable for the UK

Many varieties of New Zealand Flax are suitable for the cooler and wetter conditions of the UK, including:

•   Phormium ‘Tenax’: The traditional form with tall, green leaves, very hardy and robust.
•   Phormium ‘Bronze Baby’: A smaller variety with bronze-coloured leaves, ideal for smaller pots.
•   Phormium ‘Sundowner’: Features leaves with a beautiful mix of pink, green, and bronze, adding a splash of colour.

Maintenance

Phormiums are relatively low maintenance. They require watering during dry spells and benefit from an annual feed with a general-purpose fertiliser in spring. Over time, the centre of Phormium plants can become woody and less attractive, at which point they can be divided or replanted.

Overwintering

In the UK, while New Zealand Flax is quite hardy, it benefits from protection during particularly cold winters. In pots, ensure they are in a sheltered spot or wrapped with horticultural fleece to protect against frost.

Propagation

Propagation is generally done by division in spring. Mature clumps can be split with a spade and replanted to rejuvenate growth and increase stock.

With their dramatic foliage and adaptable nature, New Zealand Flax is a fantastic choice for those looking to add both colour and structure to their garden through pot cultivation. This makes them particularly appealing for urban or patio gardens in the UK where space and conditions might be limiting.

Characteristics

Fatsia japonica is an evergreen shrub, prized for its broad, palmate leaves which can grow up to 40 cm in diameter. The leaves are deep green, and their leathery texture along with the plant’s sturdy, upright growth habit makes it a striking addition to any garden. In autumn and winter, it produces white flower clusters followed by black berries, adding seasonal interest.

Growth and Care

Fatsia japonica thrives in shaded or semi-shaded areas, making it a perfect choice for gardens that receive limited direct sunlight. It prefers well-drained, fertile soil and can tolerate urban pollution, making it ideal for city gardens. This plant is quite hardy in the UK, able to withstand temperatures down to -10°C, though young plants or those in very exposed conditions may need protection from severe frost.

Uses in Landscaping

•   Architectural Flair: Its bold leaves provide architectural interest and can create a focal point in a shaded corner of the garden, as seen in this setting.
•   Container Gardening: Fatsia is well-suited to pot culture, which is an excellent way to control its size and fit into smaller urban spaces or patio gardens.
•   Backdrops and Screens: Its dense growth can serve as an effective backdrop for other plants or as a natural screen, adding privacy and greenery to garden boundaries.

Integration in This Garden Setting

In the garden pictured above, Fatsia japonica is used effectively to enhance the tranquillity and seclusion of the space. Its broad leaves complement the softer textures of surrounding ferns and grasses, while contrasting sharply with the rigid lines of the rectangular pond and pavers. The plant’s placement near the water feature also reflects the leaves beautifully, doubling their visual impact and reinforcing the garden’s serene atmosphere.

Maintenance

Fatsia japonica requires minimal maintenance. It should be watered regularly but can tolerate some drought once established. Annual mulching and a feed with a general-purpose fertiliser in spring will help maintain its vigour. Pruning is rarely necessary but can be done to maintain desired shape and size.

Propagation

Propagation of Fatsia japonica is generally straightforward, typically by seed or by division of the rootball. This allows for easy multiplication of plants to use throughout the garden or to share with fellow gardeners.

5. Bamboo, shown in the image below, as part of a contemporary rooftop garden, serves as an excellent example of how this versatile plant can be used in modern landscaping, particularly as an effective screening plant.

Characteristics of Bamboo

Bamboo is a fast-growing, evergreen plant known for its tall, slender culms and lush foliage. It comes in many varieties, ranging from short and bushy types to tall, towering species. The type depicted in the image is one of the clumping varieties, which are preferable for contained spaces as they don’t spread aggressively like their running counterparts.

Growth and Care

Bamboo thrives in well-drained soil and can grow in a range of light conditions, from full sun to partial shade. It is generally hardy but performs best when it receives regular watering and occasional fertilising, especially when grown in containers. The containers help to control the growth and spread of the bamboo, making it easier to manage and maintain.

Uses in Landscaping

•   Screening: Bamboo is particularly valued for its use as a natural screen. It provides dense foliage that can effectively block unwanted views and reduce noise pollution, making it ideal for urban environments.
•   Containers: Growing bamboo in containers, as seen in the photo, is an excellent way to use bamboo in rooftop gardens or on patios where planting in the ground isn’t an option. It also allows for flexibility in design and layout.
•   Architectural Element: Its upright growth and sleek form add a strong architectural element to garden designs, enhancing modern and minimalist landscapes.

Integration in This Garden Setting

In the garden depicted, bamboo is planted in uniform, rectangular containers, lined up to form a natural privacy screen that shields the space from external sights and sounds. The consistent use of similar containers brings a structured, orderly feel to the setting, which complements the clean lines of the paving and the modern aesthetic of the overall garden design.

Maintenance

Bamboo in containers requires more attention compared to in-ground plants. It needs regular watering, especially in warm weather, and benefits from a layer of mulch to help retain moisture. Periodic trimming will keep it looking tidy and maintain the desired height and density for screening.

Propagation

Bamboo can be propagated by dividing the root clump. For container-grown bamboo, this is also an opportunity to refresh the soil and prune the roots, which helps to control the growth and vigour of the plant.

Using bamboo as shown in the image not only enhances the visual appeal of the space but also provides a practical solution for privacy and sound insulation, making it a highly effective choice for urban gardens and terraces.

6. Euphorbia

Euphorbias offer a wide range of varieties that are particularly well-suited for pot cultivation, making them versatile choices for balconies, patios, and indoor settings. Here are some Euphorbia species that thrive in containers, chosen for their manageable growth habits, striking appearance, and ease of care:

1.  Euphorbia milii (Crown of Thorns): This is a popular choice for pots due to its compact size and decorative appearance. It features succulent stems and vibrant flowers that can range from pink to red, blooming almost year-round under the right conditions. It thrives in sunny spots and requires minimal watering.
2.  Euphorbia tirucalli (Pencil Cactus): Known for its thin, pencil-like branches, this succulent Euphorbia is striking in appearance and grows well in containers. It requires a sunny position and minimal water, making it an excellent choice for a low-maintenance indoor or outdoor pot.
3.  Euphorbia ammak: This large, cactus-like Euphorbia is suitable for larger containers. It has a striking vertical form with ribbed green stems that can show a beautiful golden hue under bright sunlight. It’s perfect for adding an architectural element to your space.
4.  Euphorbia characias subsp. wulfenii: This variety is suitable for outdoor containers, where it can add height and structure. It features blue-green leaves and chartreuse blooms in spring, requiring only moderate watering and lots of light.
5.  Euphorbia x martini: A smaller, bushier variety, it is well-suited to pot culture. Its foliage is attractive year-round, and it sports pink-flushed green flowers in the spring. It’s hardy and can cope with a range of light conditions, though it prefers full sun.
6.  Euphorbia obesa (Baseball Plant): Perfect for small pots, this round, ball-like succulent resembles a stone. It’s an excellent choice for indoor pots, particularly because it doesn’t grow very large and requires minimal care, thriving in indirect light.

Care Tips for Potted Euphorbia

•   Soil: Use a well-draining potting mix, ideally one formulated for cacti and succulents for the succulent varieties.
•   Watering: Water sparingly, allowing the soil to dry out completely between waterings. Euphorbias are drought-tolerant and prone to root rot if overwatered.
•   Light: Most euphorbias prefer bright, indirect light or partial sun. Varieties like Euphorbia milii and Euphorbia tirucalli can handle more direct sunlight.
•   Feeding: Feed with a diluted, balanced fertiliser during the growing season, typically spring through to autumn, once every month or two.

Container cultivation of Euphorbias allows for flexibility in arranging your garden or home décor, making it easy to bring nature indoors or to decorate your outdoor living spaces with these stunning and low-maintenance plants.

7. Buxus sempervirens (Box)

Buxus sempervirens, commonly known as Box or Boxwood, is a classic choice for pots and containers, due to its dense evergreen foliage, and ability to be shaped into various forms. This makes it a favoured plant for formal gardens and topiary art, but also a versatile addition to any home garden or patio.

Characteristics

Buxus sempervirens is renowned for its small, glossy leaves that form a dense, lush canopy. It grows slowly and can be pruned into nearly any shape, which is why it’s often seen in elaborate topiaries and formal garden borders. The compact nature of its growth and its tolerance of frequent clipping make it ideal for detailed sculptural forms.

Growth and Care

Boxwood thrives in well-drained soil and can grow in both sun and partial shade, though it prefers a bit of shelter from the strongest afternoon sun to prevent leaf scorch. In pots, it is essential to ensure good drainage and to use a quality potting mix that retains moisture without becoming waterlogged.

Uses in Landscaping

•   Topiary and Formal Designs: Boxwood is perhaps best known for its use in formal topiary, where it can be clipped into spheres, cubes, or more intricate shapes.
•   Containers: Its ability to thrive in a container makes it suitable for flanking doorways, patios, or as part of a balcony garden. Containers can also help prevent the spread of Boxwood blight by isolating plants.
•   Borders and Edging: Even without intricate clipping, Boxwood serves well as a border plant, providing a neat, structured edge to beds and pathways.

Integration in This Setting

In a garden setting similar to those previously discussed, Buxus sempervirens can be used effectively in pots to create symmetrical designs, either by placing identical pots at intervals along a path or by using a series of plants to frame a garden feature like a fountain or statue. Its dense foliage provides year-round interest and texture, adding depth and greenery to any garden design.

Maintenance

Buxus sempervirens requires regular watering, especially in pots, as containerized plants can dry out quickly. It benefits from feeding with a balanced, slow-release fertiliser in early spring, and again in mid-summer to support its dense growth. Pruning should be done in late spring after the last frost to shape the plant or maintain its size, followed by a lighter trim in late summer if necessary.

Propagation

Propagation is typically done through cuttings taken in late summer. These cuttings can be rooted in a mix of sand and peat moss under high humidity, which is easy to achieve at home with the use of a plastic cover or propagator.

With its elegant appearance and versatility, Buxus sempervirens is ideal for those seeking a plant that offers both beauty and functionality. Whether used in traditional formal designs or more modern, casual settings, its robust nature makes it a staple in garden design, especially when grown in pots for added flexibility and style.

8. Yucca

The Yucca plant, with its dagger-shaped leaves and tall, central flower spikes, screams drama. While it’s native to the Americas, it has found a loving home in many UK gardens.

Tips for Growing Architectural Plants in Pots:

Architectural plants can breathe life into your outdoor space with their bold presence. Whether you have a sprawling garden or just a balcony, incorporating some of these plants into your design will make a statement that’s hard to ignore.

•   Choice of pot: Ensure your pot is large enough to support the growth of the plant. It should also have proper drainage to prevent waterlogging.
•   Soil: Most architectural plants prefer well-draining soil. Adding grit or sand can enhance drainage for those plants that dislike sitting in moisture.
•   Feeding: Regularly feed your plants during the growing season to ensure they remain vibrant and healthy.
•   Protection: While many of these plants are hardy, some might need protection during severe frosts. Always research the specific needs of each plant.