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Bringing Structure into the Garden with Architectural Plants

Updated: Aug 26

Structure in the garden is huge, it provides visual balance and depth, creates boundaries and helps to contain and show off free spirited plantings.


Masses of Alliums and spikes of Perovskia add a unique structure in the garden.

You'll find that there are loads of 'rules' in landscape design and architecture that tell you how to add structure to space. And while important in the big picture, for our purposes today all you need to know is that humans like certain things. We seek organization, we like to find patterns and connections between objects. It gives us an idea of where we fit into the scheme of things and makes us feel comfortable and at ease. In fact, we often do this without even thinking about it. Our eye travels between objects comparing and connecting them all with a glance. It's amazing and complex but we can simplify it for our needs.


In garden design, what all that boils down to is repetition. If we repeat elements it creates a structure and the more complex that structure is, the more interesting it is to us. We can do that with hardscape like walls, walkways and buildings. Or, with surfaces like turf grass and brick or even through the addition of hedges or trees. But what if you don't have the time, budget or space for these more involved elements?


Simple forms and colour create a rhythm in this planting.

I like to add extra structure to our designs through the plant material itself. In fact, you can add a unique framework and rhythm to your garden without a lot of effort by repeating plants with similar attributes. Tall branching stalks, interesting seedheads or a unique colour pallet are all useful building blocks. They're elements that can provide support, add textural contrast and create the structure that we all desire in your own garden without the need for a construction crew or a bank loan.


A huge bonus in using plants this way, is that they are living material (vs. the majority of hardscape). They evolve seasonally so you get to enjoy their full lifecycle and witness them functioning as a valuable piece of your local ecosystem. They naturally move and combine in surprising and unusual ways while encourage birds, insects and other wildlife into the space. They're also easy to replicate, move and manage (well most of them are anyway). What could be better right?


Beth Chatto's gravel garden uses architectural Verbascum and Eryngium that repeated through the beds.

Before I talk about specific plants, I'd like to talk about how to use them. Where they're planted is just as important as what plant material you chose. We need to consider how the plants are organized in the space. There are lots of patterns to chose from: drifts, masses or clumps, mixes or groups can all echo patterns found in nature, on a smaller more considered scale. Think about what kind of landscapes make you feel, the way that you want to in your garden and consider using those same patterns. Think woodland vs meadow which could translate to drifts vs small clumps? And use whatever the plants particular attributes are to make the desired pattern. Look at shape and form as well as colour and texture.



The Lurie garden uses repeated colours and textures to build structure.

Think about planting in groups to give your choices more impact and consider the individual colours and architecture in each of your plants and how they might relate to each other in different combinations. But don't get too bogged down in all the possibilities, trust your intuition and when in doubt take your time laying out before you plant. Don't be afraid to move things around and play with the different elements until it feels right. And also remember that plants are living things and they will change over time. In fact one of the things that I love most about horticulture is that gardens are like living sculptures that can be adjusted over time. I'm constantly thinking about how each planting is working, what's successful, what could be moved in order to make it function better. It's a puzzle that never gets old.


The White garden at Sissinghurst where colour builds structure.

I've included some of our favourite architectural plants that we love in the Vancouver, Canada area (Zone 8). They all have a unique element that when repeated can add structure to a composition. Please note, we do believe in the right plant for the right place at Simple Leaf, so if your conditions (soil, climate, resources etc) don't match those needed by these specific plants, take them as inspiration and find the material that is best adapted to your unique situation yet still gives you the same feeling as these choices.




Eryngium (Sea holly) - Sea Holly is available in a variety of sizes and colours including white, green and blue. Typically they have spiky bracts and foliage, prefer lean, dry soils and add a really unique visual element to your garden. In fact, they often become a talking point with visitors! Plus pollinators love them. Eryngiums look great pared with contrasting foliage like wispy grasses and hot coloured flowers such as red echinacea. And although the flowers aren't super showy they do have beautiful seed heads that often last well into winter.



Hosta - A shade garden staple that has really come into it's own in the last few years with loads of amazing new varieties. Hosta's generally have large broad leaves (although there are many smaller and even tiny cultivars available) and come in a wide range of colours like blue, green, white, silver, chartreuse and also variegated forms. They're a great perennial that need little care (I would suggest cutting back old leaves in fall as they tend to rot in our wet winters here). Hosta's look fantastic paired with feathery ferns, forest grasses and mossy rocks.



Allium (Ornamental onion) - One of our favourite bulb families. Alliums can be spectacular in a garden setting. Their stalks shoot up in early spring and produce globe shaped flowers in purple, blue and white shades by mid summer. They come in a variety of sizes and heights need basically no care and their glorious seed heads will last well into the winter months and are breathtaking with frost clinging to them. Alliums fit into meadows and perennial borders with ease, popping up amongst the other plants. They also make a dramatic statement when planted en mass.



Phormium (New Zealand flax) - These beauties are available in a huge rainbow of colours; plum, army green, yellow, red and variegated as well. Phormium has a grass-like form on a large scale sometimes reaching heights of 5'. They're low maintenance but are only semi-hardy here and particularly wet or cold winters can be tough on them in our climate. But we think that they're worth it for the unique structure and drama that they can add to a planting.



Helianthus annuus (Sunflower) - A brilliant annual that can be replanted every year and never fails to elicit a smile. Sunflowers are usually yellow but are also available in many different forms including white, red, orange and pale green. They come in single and multi-stem forms and many different sizes including some that can reach heights of 20'. They are easily planted from seed directly in the garden after the last frost of Spring and require very little maintenance. Sunflowers add interest and architectural focal points in a planting and look great reaching out from naturalistic meadow plantings or mixed in with contrasting perennials like Perovskia and Nepeta.



Thalictrum (Meadow rue) - A little used perennial where we live, it's really something special. Thalictrum has low growing foliage with open umbels of hundreds of tiny flowers on tall wiry stems. They look like white, pink or purple clouds floating above the other plants. Like most of our picks they require a cut back before they regenerate in the spring, otherwise they are easy to care for and they have great delicate feathery seed heads for months after their spring flowering finishes. Thalictrum partners beautifully with Alliums, lupins and Salvias in mixed plantings.



Verbascum (mullin) - Verbascum are an easily self seeding biennial that come in several forms and colours, including those with wooly foliage and stems with white or yellow flowers as well as smaller purple ones on wiry stems. They can be quite large with broad full leaves and tall spires of blooms. Placement can be difficult to control as they can't be transplanted and are best left where they chose to emerge, but that's part of their charm. Mullin add an unexpected element that lends itself to a slightly messy or wild garden. they look particularly good with Hollyhocks and Perovskia.



Angelica - Another biennial that requires a bit of patience but is well worth the effort. Angelica is usually seen in a limited colour range of white, green or purple. It's tall umbels of flowers bring height and interest to a composition. They tend to self seed and are best left where they pop up. Angelica looks divine silhouetted against a backdrop of tall grasses or polka dotted throughout a sea of Salvia.



Tall grasses - Add height and movement in the garden. Switch grasses like Panicum 'heavy metal' bring unusual colour and feathery seedheads. Calamagrostis × acutiflora 'Karl Foerster' and Miscanthus 'morning light' are also favourite easy care options for a bulky statement.



Verbena (bonariensis) - Tall and wiry stems allow this hardy perennial dance in the breeze. Tiny purple flowers decorate the tips of multi stemmed umbels. Verbena is pretty much a zero maintenance trouper that will gently spread through beds over the years, but is easily pulled out if they end up where they aren't wanted. They look tremendous in a mass planting where they form clouds of blooms or popping up in a dry planting of Eryngium and poppies.


Sara-Jane & Alicia at simpleleafdesign.com


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