Another dimension: making use of form

The tagline to my website is ‘the sensory pleasures and earthy delights of gardening’.  What I mean by that is making the most of all the sensory qualities of plants in the garden, in order to really enjoy all it has to offer.

Our enjoyment of the garden includes taking in information from all our sensory modalities: visual, auditory, tactile, olfactory and gustatory.  There is also movement, which might involve our kinesthetic, vestibular and proprioceptive awareness.

Why am I so obsessed by these things?  Maybe because of yoga; I have practised yoga since my early twenties and it has influenced the way I experience the world.  I am aware that being outside and in nature makes me feel good: calm, delighted, joyful, where I am supposed to be.

Maybe I am also interested in the sensory-motor experience of the world because of my job.  I am a speech and language therapist working with complex needs.  In order to make a connection with the children I work with, I often need to try to experience the world the way they do, which may be using a different profile of sensory experiences to the one I am used to.  For example sound or touch might be more meaningful.

Last week I wrote ‘Using the Colour Wheel to plan your garden‘.  This week I thought I would talk about form, or the overall growth habit of a plant.  I will come back to flower form in another post!

Nature is incredible in its diversity.  When I was collecting together photos to illustrate my points for this post, this struck me all over again.  I cannot possibly cover the incredible range of plant forms in one post, but I will take you through the basic shapes that I like to use and combine in the garden to create a varied, sculptural display.

If you happen to be here because you are thinking about the garden from a Visual Impairment perspective, then I would advise that you talk to the person with VI to get to know what they can see.  They are likely to have some vision, but it may be very blurry, or their visual field may be restricted, or they may have visual perception difficulties.  You want to avoid a very mingled design where lots of flower forms and colours jumble together.  Clear contrasts of light and dark colour blocks are likely to guide a person with VI around the garden.  Coherent areas with a consistent tactile, auditory or olfactory quality will make more sense than a jumbled jungle.

When I am planning a border, I want a variety of shapes to create interest.  I might think about verticals, horizontals, mounds, arches and explosions.  I prefer to plant in groups of three so that your eye can really settle on an area, and so that there is an interesting contrast with the neighbouring varieties.


These are the upright spikes.  They include lupins, salvias, digitalis, verbascum, gladioli, hollyhocks and delphnium.  The taller ones lead the eye up to the sky and give a sense of enclosure.  The shorter ones create coherence and can mark a clear boundary between one planting group and another.  You can think of them as the trees or the skyscrapers in the mini landscape of your border.  They can hide views to create intrigue as you move around the garden.

Salvia nemorosa 'Caradonna' and Lupin 'Gallery Red'
Salvia nemorosa ‘Caradonna’ and Lupin ‘Gallery Red’


The horizontals carry all their flowers at a similar level, at the top of an upright stem.  They provide the ‘plains’ or the ‘hills’ within the landscape of a border.  I use euphorbia and phlox for this purpose; The umbels are also good: ammi and fennel, for instance.  Achillea is a classic ‘plate’ shape.

Achillea ‘Terracotta’. The horizontals contrast with the verticals in the bed behind.


These are the soft pillows that are really useful for the edges of borders.  They can spill over the edges to create a feeling of profusion.  They are the ‘Magic Porridge Pot‘ plants that get higher and higher and threaten to topple over by high summer.  I would include shrubs like roses and hydrangeas and peonies, and my favourite herbaceous perennials, hardy geraniums, Alchemilla and phlox in this group.

Rosa ‘Lady Emma Hamilton’ and Geranium ‘Anne Thomson’. Both are mounds, but the rose is a more structured, stiffer mound. The Geranium is a soft, pillowy mound. Which is why they work so well together.


Then there are the plants that grow up, and then arch over gracefully.  At the larger end of this are the buddleia, and climbing roses and clematis, which are really useful for providing height at the back of the border, and for growing up obelisks or through larger shrubs.  The smaller arches come from herbaceous perennials like crocosmia and fuchsia.

Crocosmia ‘Emberglow’. The foliage of Crocosmia is initially a ‘vertical’, but once the flowers open, the whole plant becomes a softer arching shape. Impossible to resist brushing your hands through.


And finally there are the firework explosions.  They are like splats of paint, or the ‘POW’ ‘WHAM!’ bubbles that smack you in the forehead.  They might be flower spikes carried above the main mound of the plant, as if they are hovering mid-air.  These are the most sculptural of flower forms and can take intricate and incredible shapes.  I would include aquilegia, allium, euphorbia, hemerocallis, helianthus, agapanthus and dahlias.  Most annuals are explosions of complex flower form: zinnias, nicotiana, nigella, scabious, dahlias…

Hemerocallis ‘Crimson Pirate’. The foliage starts of similar to Crocosmia, but whilst crocosmia leaves are upright swords, hemerocallis foliage arches over. Then the flower stems rise above it all, and burst like fireworks.

Of course there is overlap between these broad categories.  You can have arching mounds (like fuchsias and crocosmia).  You can have upright foliage with horizontal plates of flowers (like helenium or echinacea).  Roses can be arches or they can be explosions. 

As with colour, this framework gives you a starting point, but you can play with it and challenge it, and do unexpected things once you understand the basics.  Once you have the vocabulary, you can describe the effects you want, or those that are delighting you in a border.

Shall I finish with some examples of these forms being used in combination?  I will try to describe the effect I am seeing.  Feel free to disagree: we all process sensory information differently; this is the joy of the garden!

First, verticals of Salvia nemorosa Caradonna contrasted with the mound of Rosa ‘Lady Emma Hamilton’.

Salvia nemorosa ‘Caradonna’ and Rosa ‘Lady Emma Hamilton’.  There is a contrast of form and colour.  This reminds me of a landscape with vertical trees in the foreground and a mounding hill behind.

In the picture below, Euphorbia griffithii ‘Fireglow’ has vertical stems but horizontal leaves and florescences.  Rosa ‘Thomas a Becket’ has explosions of flower held above mounding foliage.  The Geranium is also a mound.  This is a very complex combination seen from this angle across the border.  If I was designing this as a VI garden, there would be much clearer separation of these groups of plantings.

Euphorbia grifithii ‘Fireglow’ with Rosa ‘Thomas a Becket’ and Geranium ‘Brookside’ behind.

There are strong verticals from the crocosmia foliage here (though you do get diagonals to add interest!), with a background of softly mounding geranium.

Crocosmia foliage with Geranium ‘Brookside’ behind.

To summarise,

  • I broadly categorise plant forms into verticals, horizontals, mounds, arches and explosions.
  • But these categories can overlap and change as the growing season progresses.
  • You can make use of these different shapes to provide contrast in a bed, and to create visual interest.
  • Planting in groups of three will give a more coherent effect, allowing the eye to rest on one form or another.
  • Rules are meant to be broken.  Feel free to ignore that if you have a good reason to!  Gardening is all about personal preference and enjoyment.

How do you think about or use plant form in the garden?  Do you have a different way of thinking about form?  I would love to hear your views.

If you have enjoyed this post, then consider clicking the ‘Follow’ button at the base of this post. You will receive an email every time I post. You can also share the post via the usual social media channels, and via email.

My aim in this blog is to share the little pops of wonder I get from gardening and from nature. You don’t have to be into gardening to appreciate these. The world is an amazing place and there are so many sensory pleasures that go unnoticed.

20 Comments Add yours

  1. Such a lot of thought goes into your posts

    1. Ali says:

      Thank you Derrick.

  2. pommepal says:

    As always Ali you give me a different perspective to planning the garden. I must admit I am usually very haphazard with my planting but now I will look at my plants differently. Maybe another restructuring coming up….

  3. That’s really cool. I had no idea you were a SLP. I’m an OT. 😊

  4. FlowerAlley says:

    This lovely and well written. I need to mix forms better in some places.

    1. Ali says:

      It’s a gradual process. Never finished!

  5. bcparkison says:

    Need to keep this in mind as I redo my pitiful garden beds. Right now I am still in the dig it out stage.

    1. Ali says:

      Ooh, I love replanting a border!

      1. bcparkison says:

        I could use help LOL

  6. Heyjude says:

    I am aware of shapes and forms but do I consider it in planting? Hard to answer this as for 10 or more years I was restricted to pots, and only a few of those. I did select plants for them based on colour and height. Now having a garden with unusual borders, I am finding the selection of plants much more difficult and based more on the conditions of the garden rather than the plants. And I suspect there will be several changes until I get it right! As Derrick said, you do put an awful lot of thought into your posts and the attention to detail you provide makes them so very interesting.

    1. Ali says:

      Thanks Jude. I think these choices have come second to colour, and it has perhaps been in the tweaking and replanting when I have given thought to form.

  7. Christina says:

    I haven’t been writing so much about my actual garden recently so I don’t suppose you’ve seen any of my posts about form – which because of our long, hot, drought for 3 month summers depends a lot on texture and form for its interest. If you converted all your lovely images to monotone (black and white) you’d see even more clearly what you were writing about. For many people when there is colour that is what they consciously see.

    1. Ali says:

      Ooh. I will try this. Thanks Christina!

  8. This post was especially interesting to me. I loved hearing about your job! I didn’t know this about you. I also really appreciated it from an educational background because one of the things I think about in my classroom is how I can teach in a way that engages the different modalities or senses of my students. I think this makes for more holistic teaching. So, I love the idea (and it makes sense) of gardening engaging all of our senses. Thank you for this lovely, thoughtful post.

  9. Antonia Elisabeth Noal Silvera says:

    Belissimas. Parabéns.

  10. Lovely, lovely post with gorgeous pictures. I’d forgotten a lot of the detail in planning a bed and this is a good reminder. Katie

  11. Anonymous says:

    Ali, thank you for this post. Its very inspiring.

    1. Ali says:

      I’m glad you enjoyed it.

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