Growing Grevilleas

Develop your ability to select and cultivate appropriate varieties of Grevilleas in different situations.

Grevilleas are a wide group of plants, all but seven species coming from Australia. They are widespread across Australia, occurring in both cool temperate, and hot tropical climates.

There are around 250 species. About half of these are native to the south west corner of Australia.

Known commonly as “Spider Flowers”; the Grevillea flower is more like a brush than a traditional flower. It has obscure petals, but is none the less very colourful. Flower colour varies greatly; and most hold their flowers for a long period.

Grevilleas include both small to very large plants (from prostrate ground covers, through small and medium shrubs up to large trees).

Their hardiness is variable according to species. The foliage is also variable ranging from small, entire leaves to lobed or pinnate leaves. All are arranged alternately on the stems and some have hairy undersurfaces.  Most have a medium to fast growth rate.

“There are so many of these wonderful colourful plants in our gardens today. Not only are they striking to look at, they also attract birdlife. It really is worth getting to know them a little bit better.”- Tracey Morris Dip.Hort., Cert.Hort., Cert III Organic Farming, ACS Tutor.

Lesson Structure

There are 8 lessons in this course:

1. Introduction.
   • Review of the system of plant identification, general characteristics of Grevilleas, information contacts (ie: nurseries, seed, clubs etc.)
2. Culture.
   • Planting, staking, mulching, watering, pest and disease, feeding, pruning, protection from wind, salt air, etc.
3. Propagation.
   • Methods of propagating Grevilleas. Propagation of selected varieties.
4. The Most Commonly Grown Varieties.
5. Other Important Groups.
6. Other Grevillea Varieties.
7. Making The Best Use of Grevilleas.
   • In containers, in the ground, growing for profit etc. (to sell the plants) etc.
8. Special Assignment. On one selected plant or group.

Each lesson culminates in an assignment which is submitted to the school, marked by the school's tutors and returned to you with any relevant suggestions, comments, and if necessary, extra reading.

Aims

• Identify a range of different Grevilleas.
• Explain the culture of different types of Grevilleas.
• Propagate different Grevilleas
• Discuss different uses for Grevilleas
• Compare identifiable characteristics and cultural preferences of a range of Grevilleas.
• Discuss a range of Grevillea hybrids and cultivars
• Identify and compare a range of commonly cultivated Grevilleas.
• Discuss one Grevillea species, cultivar or type in depth.

Extract from Course Notes

Grevilleas come in all shapes and sizes, from low ground covers to tall trees. Here are some examples of those extremes:

GROUND COVER GREVILLEAS

Grevillea aquifolium (Prickly Grevillea)
Growth: 4 wide x 1.5m high
Grevillea aquifolium is a dwarf to medium shrub with a prostrate habit. Flowers are green red and sometimes yellow. Flowering is usually scattered but occasionally profuse; a reliable plant which is popular in temperate regions. It is frost and dry tolerant. It occurs naturally in heath or woodland areas in well drained sandy or gravel soils. Generally grows in acidic soils, however is also tolerant of alkaline soils.

Grevillea australis
Growth: 0.1-2.5m x 1.5-3m.
Grevillea australis is a dwarf to medium shrub with spreading ascending branches. It naturally inhabits subalpine and alpine areas of South Eastern Australia. Flowers are cream, sometimes profuse, and inconspicuous with a sweet scent. The plant is hardy, frost and snow tolerant.

Grevillea confertifolia  (Grampians Grevillea)   There are three forms occurring naturally,  occur naturally on moist sandstone soils, woodlands or open forests, in temperate south east Australia.
Habit - usually low growing spreading plants; but can also occur as small shrubs to 1.5m tall.
Leaves are needle like to 3 cm long, Low growing ground cover habit, growth tips can tend to be covered with fine hairs.
Flowers - either wine red or rosy pink, short toothbrush type to 1cm.
Conditions - tolerates frost and light snow.
Problems - humidity can be a problem (better in drier climates), Pests may include: scale, leaf miners, caterpillars (causing webbing).

Grevillea robusta    (Silky Oak)
Grevillea robusta is a very popular ornamental tree. It is endemic to Queensland and New South Wales and grows in rainforests. It is a small to medium sized tree with either a spreading or an elongated crown (to 30 meters).
The flowers are brilliant orange and in racemes and rich in nectar, which attract nectar feeding birds. The wood is harvested and prized by furniture manufacturers.

The tree is grown widely in many countries around the world. It is hardy and adaptable; it will tolerate numerous climates and soil types.

Grevillea striata (Beefwood)
Habit – a small to medium slow growing tree with a narrow crown. Leaves - 10-50cm long and 0.3-1cm wide. Narrow at base, linear, and often curved.
Flowers - are cream and fragrant and crowded on racemes which are 7-13 cm long. Attractive to nectar feeding birds.
Conditions - originates from watercourse of inland Australia. Drought and frost tolerant.
Propagate – from seed.