Planting Centres & Densities

How many shrubs are required? To answer this question, follow these simple steps. Firstly, determine the planting centres (that is, how far apart the shrubs will need to be planted) using the table below, by giving some thought to what the approximate spread of the shrub will be after say, 10 years. Remember to reduce the spread by 10% if the plants are for the cooler northern areas of Britain. The following will act as a useful guide when considering shrubs in pots no greater than 3 litres:

Spread of Plant   For Garden Schemes   For Landscape Schemes   For Difficult Locations
0.5m = 400mm - 400mm - 400mm
0.6m = 500mm - 500mm - 400mm
0.7m = 500mm - 500mm - 500mm
0.8m = 600mm - 500mm - 500mm
0.9m = 700mm - 600mm - 600mm
1.0m = 800mm - 600mm - 600mm
1.2m = 1100mm - 600mm - 600mm
1.3m = 1200mm - 700mm - 600mm
1.4m = 1200mm - 700mm - 600mm
1.5m = 1300mm - 700mm - 600mm
1.6m - 2.0m = 1300mm - 800mm - 700mm

Having worked out the planting centres, it is now possible to determine the planting densities, that is, the actual number of plants required per square metre (m2), by using a second table provided below:

Centres   Number of Plants   Centres   Number of Plants
350mm = 8.16 / m2*   800mm = 1.56 / m2
400mm = 6.25 / 2   1100mm = 0.83 / m2
500mm = 4.00 / m2   1200mm = 0.69 / m2
600mm = 2.78 / m2   1300mm = 0.59 / m2
700mm = 2.04 / m2   1500mm = 044 / m2

For example, if a plant with a spread of 0.8m is to be used within a landscape scheme, the centres should be at 500mm & the density 4 plants/ m2. Thus, a scheme with a 10m2 shrub bed will require a total of 40 plants.

* For small-scale schemes, figures for densities should be rounded up to the nearest half or whole number before calculating the total number of plants required.

'Growing to raise Standards'