Plant arrangement

Before you start choosing plants, it is important to know that some plants are considered noxious weeds or pest plants and may be regulated by your council.

For example Agapanthus (Agapanthus praecox) is considered a pest plant in Auckland. 

Others must be actively destroyed, such as African feather grass (Cenchrus macrourus). The Auckland Council webpage for this pest plant states:
“To help protect our environment:

• You must not breed, distribute, release or sell African feather grass within the Auckland region.
• You must not plant African feather grass within the Auckland region.

Auckland Council will control African feather grass at all sites where it is known to occur. If you see African feather grass anywhere in the Auckland region, please report it to Auckland Council at pestfree@aucklandcouncil.govt.nz.” (Auckland Council, no date a)

You can search the Auckland pests database here: https://www.tiakitamakimakaurau.nz/protect-and-restore-our-environment/pests-in-auckland/pest-search/ 

Activity

Different regional councils (or unitary authorities) have different plant pest lists. Find your council’s plant pest list – it could be found as a list in the regional pest control plan – and take a look at the species listed.

Are you surprised by any of these? Share your findings and read and respond to others in the Forum.

In the last module we talked about historical garden styles and garden themes. Garden themes (confusingly sometimes also referred to as garden styles) are a way of categorising gardens that have similar elements. 

The following websites provide some useful inspiration for plant selection for a range of different garden themes:

• Gardenia: Garden styles
• Royal Horticultural Society: Choose your style

The Hamilton Gardens website serves as a useful resource if you are drawing inspiration from one of the historical garden styles.

Use these websites for inspiration as to what types of plants go together, not necessarily the specific plant species. For example, “upright perennial to 1m, with coarse, glossy leaves and white flowers matched with a weeping tree with fine textured leaves and medium textured bark”.

Planting in odd numbers

When you’re going for an organic, or asymmetric design, it is a good idea to plant in groups of 3, 5, or 7. The human brain is good at recognising patterns, and it picks up on instances where plants have been arranged in even numbers and automatically treats this as unnatural. The ability to recognise this pattern seems to stop when larger numbers are involved, typically more than seven.

Of course, if your garden design is highly symmetrical, using pairs of identical plants on either side of your line of symmetry is a suitable alternative.

Planting feature plants in triangles

Where feature plants – which are usually trees or large shrubs – are being planted in groups, the most common approach is to plant them in threes in the shape of a scalene triangle. A scalene triangle is one where all three sides are different lengths. The same is true even in the case that the plants are some distance apart. 

Planting garden beds

Watch the following video, How To Arrange Plants in Garden Beds (4 Simple Ways)-(12:33 minutes), where Amy Fedele, from Pretty Purple Door explains four common approaches to plant arrangement. 

This video introduces four basic plant arrangement approaches: the drift, the start, the tier, and the weave. 

Pre-watch Question: Do you know what any of these terms mean in relation to planting design?

Post-watch Task: Look at the working copy of your proposal plan and identify which plant arrangement approaches you will use and where, if any.

If you’re planning on creating a more natural, low maintenance, planting design, watch this interview with garden designer Michael McCoy about naturalistic planting: Naturalistic planting design - how to get it right in your own garden (14:40 minutes)

Top garden designer and broadcaster Michael McCoy tells us about the key tips on naturalistic planting. It's super low maintenance and looks good for months at a time, including in winter, so find out how to adapt this trend for your own garden.

Pre-Watch Question: What do you think the term naturalistic planting design means?

Post-watch Task: Reconsider your proposal plan and update to indicate any garden beds where you might use naturalistic planting.

As Michael points out in the video, naturalistic planting relies on drifts and use of the upright, round, and horizontal forms.

He emphasises that form and mass planting are more important than precisely selecting plants for their flower colour. This is true for other planting approaches too.

Variation of size, form, texture, and colour

To create interest in the garden, variation is key. Try pairing:

• fine with coarse textures
• upright with round or horizontal forms
• small with large plants
• tall with short plants
• plants with contrasting colours.

This photo from Brooklands Zoo in New Plymouth shows an effective planting arrangement consisting of (from left to right) fan palms, tractor seat plants (Cremanthodium reniforme, syn. Ligularia reniformis), and orange day-lilies (Hemerocallis fulva). The tractor seat plants break up the linear texture of the plants on either side, and collectively the plant heights mirror the ramp.

The following, guidelines are useful for various colour schemes:

• Monochrome: Use one-third of the more vibrant colour with two-thirds of the darker colour. 
• Complementary: Use one-third of one colour with two-thirds of the complementary colour.
• Analogous: Use least of the plants with the most dominant colour. Select the plants with the next most dominant colour and increase the number by one-third. Repeat this for each subsequent colour (Whiting and de Jong, 2014). For example:

Flower colour	Calculation	Total number of plants
Red (dominant colour)	—	15
Orange	15 + ⅓ of 15	20
Yellow	20 + ⅓ of 20	27
Pale yellow	27 + ⅓ of 27	36

Remember though, as a general rule, gardens should be 90% foliage (generally green) and only 10% other colours, by way of flowers and fruit. Too much colour will overwhelm the viewer.

Don’t get too carried away. If in doubt, use the principle of simplicity: you are better to have too few different types of plants than too many.

In this topic we’ve:

• learned about pest plants and where to go to find out which species should not be specified in your garden design 
• provided sources of inspiration for planting design for a range of common garden themes
• introduced several approaches to plant arrangement.

In the next topic we’ll work through the process of selecting the plants for our garden based on what we have just learned about plant arrangement.