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Scott Robinson

Updated on the 13th of June 2023

Subjective terms of reference relative and relevant to south western Australia (Perth).

Height Height

The typical maximum height a plant appears to grow to under good conditions and with good management.
  • That is to say that if a plant is desirably cut back annually that this is performed and that it is not left to become leggy.
  • Under exceptional conditions and with lots of feeding most plants will exceed this size (not necessarily a good thing).
  • Most plants will also grow taller the more shade they receive (etiolation != healthy plants).
  • If a plant is grown for its flowers the height of flowering stems is taken into account.
  • If a plant is grown for foliage or form and the flowers are of little consequence than flowering stems are not included in the height, for instance, Artemisia alba ‘Canescens’ is grown as a ground cover, yet it bears flowering stems in early summer that may be over 60cm tall, while I do enjoy them they don't have much effect on the overall appearance of the plant. In this circumstance I would suggest a height of 20cm as the branches rarely exceed this.

Width Width

The typical width a plant reaches under good conditions and with good management.
  • Some plants can spread almost indefinitely, e.g. Artemisia princeps ‘Crabling’, in this case width refers to a spread you can expect in reasonable period of time. A reasonable period of time = an arbitrary value based on lifespan/annual growth rate (typically 3 years).

Flowering season Flowering Season

An annual period during which you should expect blooms.
  • Precise flowering times can vary greatly from year to year and may be dependent on local conditions, temperature, photoperiod, moisture levels, humidity, nutrient availability, genes, age..........

Water Water

The amount of summer moisture expected to produce a healthy and natural looking specimen.
  • L = Low, happy to grow with only natural rainfall across most of the south west of W.A. and may be intolerant of much summer moisture.
  • M = Moderate, regular summer irrigation is necessary for growth and survival but periods of dryness are tolerated once established. A soak every two weeks would be a good reference point.
  • H = High, needs constantly moist soil, intolerant of dryness, this might mean daily watering during the height of summer.

  • Water requirements are dependent on many factors, soil type, exposure, age, size, mycorrhizae to name a few. Many plants will survive outside these parameters but I would not expect them to be healthy. Bear in mind too that bigger and lusher faster does not necessarily equate to healthy, hardy and long lived.

Light Light

The amount of sunlight a plant requires for natural growth and flowering.
  • Full Sun means full W.A. summer sun without a tree or other light blocker in sight for best results. These plants have means to deal with high leaf surface temperatures and often demand high light intensity to function properly.
  • Sun, as above but less demanding, some shelter may be of benefit.

  • Light shade, can be from thinly foliaged trees or full morning sun with shade from noon onwards.

  • Shade, equivalent to the shadow on the south side of your house in winter.
  • Remember, plants get their energy from the sun, generally more sun = more energy for growth, flower and seed production. A mediterranean climate is typified by high light intensity and temperatures in summer, to which the plants are adapted. Shade may lower temperature but it also decreases available light, to which shade loving plants have a different set of strategies. Plants from cooler or more humid climates may not cope with high leaf surface temperatures and aren't necessarily suited to shade.