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Houseplant design principles: scale

Learn how to use scale and proportion to maximise the visual impact of your houseplant displays

To put it simply, scale refers to the relative size of objects. A plant may be large or small, but its relalationship with neighbouring plants or objects is what defines its scale.

Proportion describes the size of your plants within a display, and along with scale it's key to any successful design. A tiny cactus next to a giant weeping fig, for example, would look totally out of scale and proportion with each other. 

There are several ways in which you can play with scale and proportion to create satisfying houseplant displays.

Understanding scale

Equally-sized plants give a harmony of scale
Different sized plants provide contrast of scale
Plants of a similar size are harmonious in scale, while those of different heights contrast in scale. Scale is relative; any two plants can share the same contrast of scale, provided they maintain the same proportions.

Harmony of scale

A group of fiddle-leaved figs (Ficus lyrata) make a striking houseplant display
Choosing and grouping together plants of uniform size (scale) results in a classic-looking, highly ordered display. Repetition of scale and proportion creates a harmonious pattern and offers a sense of unity and simplicity. Too much repetition can become dull, but in moderation it offers a sense of order and rhythm. 

Contrast of scale

The differing sizes of these barrel cacti provides satisfying contrast of scale
When plants are in proportion but of different scales, the eye is led from one to the other – and the relationship becomes more dynamic than a harmonious display. There's a sense of movement, going from small to large, often drawing the eye to a focal point in the grouping. However, be sure to maintain proportion so that the objects still relate to each other. 

Top tip!

If your houseplant displays are looking a bit lacklustre, with lots of similar-sized dark green plants, try adding some small and brightly-coloured houseplants to add contrast.

However you choose to use scale and proportion in your houseplant displays, be sure to have fun...

This article is adapted from the RHS Practical Houseplant Book.
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