Planting design: layers and layout
Planting design means choosing and arranging plants so the site works and looks good. A few simple rules do most of the work.
- Layers: tall plants at the back (or in the centre of an island bed), middle plants next, low plants at the front.
- Groups: plant the same kind in a group of 3, 5 or 7 so it makes a clear patch of colour.
- Focal point: one striking plant that draws the eye.
- Colour and season: mix plants that bloom in different months.
- Purpose: shade where people sit, a screen where privacy is wanted, cover where soil is bare.
Plant features and site match
Before choosing a plant, check its features: mature height and spread, shape, leaf colour, bloom time, root type and how fast it grows. Then check the site: how much sun it gets (full sun, part shade, shade), the soil (sandy, loamy, clay), water and wind.
A sun-loving plant in shade grows thin and does not flower. A shade plant in hot sun gets burnt. The right plant in the right place needs less care.
Spacing by grown size
Spacing is the distance between plants. Use the mature spread (width when fully grown), not the size at purchase. A simple rule: distance between plants = mature spread.
To count plants in a bed: number = area / (spacing x spacing). For example, a 6 m x 4 m bed with plants 1 m apart needs about 24 plants.
Making the planting plan
A planting plan is a drawing seen from above. Draw the site to scale, mark the sun direction, then draw a circle for each plant at its mature size and label it with a number. A plant list beside the plan gives names, number and size. The plan is what workers follow when they plant.
Key formulas and definitions
- Number of plants = area / (spacing x spacing)
- Spacing = mature spread of the plant
- Layers: tall (back) > middle > low (front)
- Right plant, right place: match sun, soil and water
Worked examples
1. A bed is 6 m x 4 m. Shrubs with a 1 m mature spread are planted 1 m apart in a square grid. How many shrubs?
Area = 6 x 4 = 24 square metres. Each plant takes 1 x 1 = 1 square metre. Number = 24 / 1 = 24 shrubs.
2. A tree grows to a crown 6 m wide. How far from the wall of a house should it be planted?
At least half of 6 m, which is 3 m, so the crown does not touch the wall. More is safer.
3. A bed is 3 m x 2 m and viewed from the front. Where should a 1.5 m tall plant, a 0.6 m plant and a 0.2 m plant go?
1.5 m plant at the back, 0.6 m in the middle, 0.2 m at the front, so none hides another.
4. A bed is 5 m x 2 m. A flower with 0.5 m spread is planted 0.5 m apart. How many plants?
Area = 10 square metres. Each plant takes 0.5 x 0.5 = 0.25 square metre. Number = 10 / 0.25 = 40 plants.
Common mistakes
- Spacing plants by their size at purchase. They grow and crowd each other.
- Putting a sun-loving plant in deep shade because the spot "looks empty".
- Planting every plant as a single dot with no groups, so the bed looks scattered.
- Putting tall plants in front so they hide the short ones.