Plant Shape

Firstly, let's consider the four types of plant shape.

1. Round - (examples; hebes, daisies, diosma)
2. Oval - (examples; begonias, fuschia's, grevilleas)
3. Trailing - (examples; climbers, pelargoniums, prostrate creepers)
4. Columnar - (examples; most bulbs, daylilies, spathyfilum, anigozanthos)

Mixing these up create interest. If you were to have a garden that was limited to one plant shape it would look incredibly boring. Using round and oval shapes predominantly with some columnar plants added for focus draws the eye around the garden and appears enticing.

Even with different plant genus' you can get such diversity and when grouped together can create a visual banquet. Take grasses as an example, for a round option you could choose the dwarf mondo grass, an oval option might be festuca glauca, a trailing type may be the blue phlox, and a columnar variety could be Japanese blood grass.

Plant Texture

Harmonising plant texture has its own similar options;

1. Fine - foliage is fine and whispy (examples; erigeron, Ricinocarpus pinifolius)
2. Medium - foliage is a little larger and flowers may be bigger as well (examples; gardenias, plectranthus)
3. Coarse - foliage is large or at least able to support itself (examples; flax, strelitzia)

Using these well in your garden will depend on height also and what shaped beds you are working with. If you have a border bed then work with height at the back to groundcovers at the front. With a bed that can be seen from all sides, use you height in the middle and work down from there.

A tip a friend gave me a few years ago when looking for plants at a nursery was to grab the plants I was interested in and arrange them on the ground while I was there. Your ability to do this meant that you could visualise the end result much clearer and arrange, and re-arrange, them with all the options available. If the nursery doesn't have the exact plant you're looking for, you could still substitue a plant that had similar characteristics into your mix.