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.
The way you should treat a particular species of Grevillea will differ from place to place, and according to what you are trying to get from the plant.
Lesson Structure
There are 8 lessons in this course:
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Introduction.
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Scope and Nature of the Grevillea genus
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Review of the system of plant identification
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Botanical Terminology used to describe Grevilleas
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Flower Structure
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Plant Name Pronunciation
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Characteristics of the Proteaceae family
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Characteristics of the Grevillea genus
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Different ways of classifying Grevilleas into groups: by flower type (eg. toothbrush); McGilveray's system dividing into 11 groups
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Resources, information contacts (ie: nurseries, seed, clubs etc.)
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Culture
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Environment, Nutrition, Soil Requirements
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Planting, staking, mulching
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Water management
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Pest and disease found on Grevilleas
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Feeding, pruning, protection from wind, salt air, etc.
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Propagation
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Methods of propagating Grevilleas
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Cutting Propagation
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Methods to Improve Cutting Success
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Seed Propagation of Grevilleas
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Transplanting
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Hardening off and Growing on Young Plants
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Grafting Grevilleas
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Tissue Culture and Aerial Layering
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The Most Commonly Grown Varieties.
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Clearview Hybrids
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Grevillea banksii and banksii hybrids
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Grevillea alpina
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G. rosmarinifolia
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G. dimorpha
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G. lavandulaceae
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Other Important Groups.
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G. alpina cultivars and hybrids
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G. rosmarinifolia cultivars
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G. Poorinda hybrids
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Other Grevillea Varieties.
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Ground Cover Grevilleas
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Trees
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Review of many other species
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Making The Best Use of Grevilleas
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Cut Flowers
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Bird Attracting
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Scented Grevilleas
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Container Growing Grevilleas
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Potting and Types of containers
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Growing Grevilleas in Baskets
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Rock Gardens
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Designing a Garden with Grevilleas; design principles, garden styles, drawing a plan
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Special Assignment: On one selected plant or group.
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Problem Based Learning Project
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Plan the establishment of a collection of different cultivars of Grevilleas suited to growing in a specified locality.
Aims
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Identify a range of different Grevilleas.
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Explain the culture of different types of Grevilleas.
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Propagate different Grevilleas
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Discuss different uses for Grevilleas
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Compare identifiable characteristics and cultural preferences of a range of Grevilleas.
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Discuss a range of Grevillea hybrids and cultivars
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Identify and compare a range of commonly cultivated Grevilleas.
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Discuss one Grevillea species, cultivar or type in depth.
How Do You Grow Grevilleas?
Most Grevilleas prefer a freely draining soil and relatively good sunlight. Many grow well in full sun; some tolerate shade, but most of those will do better in a position with filtered light, such as under the canopy of tall trees; rather than heavy shade.
Many grow well in sands and sandy loams; but others grow equally well in clays and clay loams; provided drainage is reasonable.
If your soil is heavier (ie. Clay or clay loam);Grevilleas can still do well on a slope or embankment; or where the topography is flat; consider creating mounds or raised beds to plant Grevilleas into.
Most cultivars will need minimal feeding; and too much feeding can cause burning of tissues. Don’t use strong or fast acting fertilisers. Grevilleas, like most plants in the Proteaceae family, can be particularly sensitive to phosphorus. Don’t use fertilisers high in phosphorus.
Some tolerate excessively alkaline or acid soils better than others. Consider where the species originated.
The following are more tolerant of high alkalinity than many – Grevillea Clearview David, Grevillea thelmanniana ssp preissii and Grevillea shiressii
There are some species that have tolerated periods of wet and poorly drained soil, including:
G. barklyana
G. bipinnatifida
G. conferifolia
G. diminuata
G. juniperina
G. lavandulacea
G. rosmarinifolia
G. shiressii
Most will respond to being watered, particularly when first planted, if conditions are hot and/or windy. Be sure the soil does not become waterlogged –don’t over water. Once a plant has established a deep and extensive root system; irrigation is usually unnecessary (except possibly in years of extended drought
Most Grevilleas come from places where temperatures rarely drop more than a few degrees below zero (Celsius).
Some species including the following, have been grown successfully in parts of the UK where temperatures can reach minus 10 degrees Celsius or more:
How are they Used
Grevilleas are widely used landscape plants in Australia; and increasingly popular in some other parts of the world. It is not uncommon to see them growing anywhere from California to England, though the range of cultivars available outside of Australia is significantly less than within Australia.
These are plants that have a great deal of potential for many reasons; not the least their tendency to flower for extended periods, and their adaptability to a wide range of climates.
Apart from being used as landscape plants, some species are also grown for timber; others are used as cut flowers, many are great for attracting birds and some are even food or medicinal plants.
Most Grevilleas will live for 10 years or more; but over time can become shabby and health can deteriorate, with parts of the plant deteriorating, until the whole plant finally dies.
Pruning and pest control can extend the life of some species
Some species can live much longer than others (eg.
G. barklyana and
G. robusta specimens have survived over 100 years)
Who will benefit from this course?
- Collectors or enthusiasts of Grevillea species.
- Horticulturists working with Australian Native Plants.
- Native cut flower growers.
- Learn about the diverse range of species.
- Understand there culture and the different propagation techniques.
Learn More about how Grevilleas sit with their relatives in the Proteaceae family.
Watch this short video.
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