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Scott Robinson

Updated on the 26th of April 2019

Deliberately vague guidelines to be subjected to interpretation based on experience with your own garden conditions.

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 (etoliation != 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.
  • Sun, as above but less demanding, some shelter may be of benefit.

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

  • Shade, equivalent to the shadow on the south side of your house in winter.
  • Plants get their energy from sunlight. Photosynthesis is more efficient at high light intensity. Some plants, particularly drought loving mediterraneans, can be intolerant of shade and will eventually die from a lack of energy, most will simply produce less flowers, require more water and be more pest prone. Some plants are adapted to shade and will scorch with too much sun. Summer growing plants from cooler, or summer rainfall regions often burn in a mediterranean South West summer, this can mitigated to some extant by providing more shade but this often means they can't get enough energy to perform as well as we would like or ever be as healthy as they should.

Easy to grow v. Hardy

Most people, gardeners or not, would refer to a Tomato plant (Lycopersicon esculentum) as easy to grow. Give it water, nutrients and sunlight, get tomatoes, yet in our climate and soils, without us constantly supplementing these resources, it would fair poorly at best. Woolly blue curls (Trichostema lanatum on the other hand demonstrates a propensity for a mediterranean climate and lean soil but I have yet to have success even germinating it and I doubt few who have would consider it as easy to grow as the Tomato. I look forward though to the day that I can label it tough and hardy.


A plant that completes its life cycle in a single year and is then exhausted.

Monocarpic (Biennial)

A plant that takes more than one year to reach maturity and is then exhausted after flowering once.


A plant that after reaching maturity continues to grow and completes more than one flowering cycle.