Callistemon citrinus 'Harkness' - Evergreen Trees Direct

Callistemon citrinus 'Harkness' – Harkness Bottlebrush

$160.00

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Size: 30cm/33cm

30cm/33cm 40cm/45L

Current Stock Height Guides

40cm/45L: Enquire within for height guide information.

Height guide disclaimer: Height ranges are approximate only. As living products, plant heights naturally vary between individual plants, batches, and seasons. No guarantee is given that supplied plants will fall within the stated range. If minimum heights are required, you mustconfirm current batch heights with Evergreen Trees Direct prior to purchase. Variation in height is normal and is not grounds for return, refund, replacement, or compensation.

Mature Height & Width

Mature Height: 2m to 4m (approx.)

Mature Width: 1.5m to 2m

Callistemon citrinus 'Harkness' – Harkness Bottlebrush is expected to grow 40cm to 60cm per year (approx.).

Root Ball Dimensions

Use this as a reference when digging your planting hole. We recommend digging at least 10% wider than the dimensions below to encourage strong root development.

30cm Pot: 33cm (W) × 30cm (D)
40cm/45L Pot: 44cm (W) × 41.5cm (D)
50cm Pot / 70L Pot: 55cm (W) × 41.8cm (D)
100L Bag: 50.6cm (W) × 52.8cm (D)
150L Bag: 66cm (W) × 55cm (D)
200L Bag: 71.5cm (W) × 60.5cm (D)
300L Bag: 88cm (W) × 63.8cm (D)
400L Bag: 99cm (W) × 66cm (D)
500L Bag: 122cm (W) × 66cm (D)
750L Bag: 134cm (W) × 69cm (D)
1000L Bag: 146.3cm (W) × 71.5cm (D)
2000L Bag: 176cm (W) × 82.5cm (D)

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About Your New Callistemon citrinus 'Harkness' – Harkness Bottlebrush

Callistemon citrinus 'Harkness' produces some of the largest and most brilliantly red bottlebrush flowers of any Callistemon, carried heavily through spring and summer with sporadic flushes at other times. The flowers are worked constantly by honeyeaters and native bees.

'Harkness' grows to 2 to 4 metres tall and 1.5 to 2 metres wide at 40 to 60 centimetres per year, holding a dense upright habit that fills in from the base. It works as an informal screen along a boundary, as a mass planting in civic and rural landscapes, or as a single specimen in a large pot.

This Australian native is frost hardy, surviving heavy and frequent frost without damage, and tolerates poor soils, extended dry and periodic wet feet once established. It grows in full sun and needs little beyond a light prune after flowering to stay dense.

Frequently Asked Questions

About Callistemon citrinus 'Harkness'

How tall does Callistemon 'Harkness' grow?

'Harkness' grows to 2 to 4 metres tall and 1.5 to 2 metres wide with a dense upright habit. It can be held lower with regular trimming after flowering.

When does 'Harkness' flower?

The main flush is through spring and summer, with sporadic flowering at other times of year. 'Harkness' carries notably large, deep red bottlebrush flowers.

Does 'Harkness' attract birds?

Yes. The nectar-rich flowers are heavily worked by honeyeaters, lorikeets and native bees, and the dense branching gives shelter to small birds.

Is Callistemon 'Harkness' frost hardy?

Yes. It is frost hardy and survives heavy and frequent frost without damage, which suits it to inland tablelands districts as well as coastal gardens.

Can 'Harkness' be used as a hedge?

Yes. Plant 1 to 1.5 metres apart for a dense informal screen. It responds well to trimming immediately after flowering, which keeps it compact and encourages the next flush.

What soil does 'Harkness' need?

It is highly adaptable, tolerating poor soils, clay, extended dry and periodic waterlogging once established. Free-draining soil gives the best growth but is not essential.

Can 'Harkness' be grown in a pot?

Yes. It performs well in large pots in full sun. Use a quality potting mix, water regularly through summer, and prune after flowering to keep the shape tight.

Enriched Planting Mix (AO Certified)

$21.95

Enriched Planting Mix is a certified organic blend of Pure Magic Compost, composted animal manure, gypsum, composted coarse bark and a wetting agent, bagged in 30L. It is built to be dug through existing garden soil at planting time rather than used on its own, and the gypsum is what sets it apart from a plain compost.

Gypsum helps break up heavy clay so water and roots can move through it, while the compost and manure return organic matter and nutrient to tired ground. The coarse bark holds structure and keeps air around the root zone, and the wetting agent keeps moisture in the soil longer after rain or watering.

Use it when planting trees, shrubs, roses, fruit trees and exotic garden plants, particularly into clay. Dig a hole twice the width of the pot and 7 centimetres deeper, then mix roughly one third planting mix through the excavated soil. Spread 7 centimetres of that improved soil in the base before setting the plant in.

Frequently Asked Questions

About Enriched Planting Mix

What is Enriched Planting Mix made from?

It is a blend of Pure Magic Compost, composted animal manure, gypsum, composted coarse bark and a wetting agent. Each part has a job. The compost and manure supply organic matter and nutrient, the gypsum works on clay structure, the bark keeps air around the roots and the wetting agent holds moisture in the soil.

What plants is it suitable for?

It suits exotic garden plants, including roses, ornamental and deciduous trees, fruit trees, shrubs and perennials, and it earns its keep most on heavy clay sites. It is a planting mix rather than a potting mix, so its job is improving soil at planting time. Phosphorus sensitive natives are the one clear exception.

Is it safe for natives?

No, not for the phosphorus sensitive ones. The composted animal manure in this blend lifts phosphorus well above what Proteaceae such as Banksia, Grevillea, Hakea and Protea will tolerate, and the result can be leaf burn, dieback and plant death. Use the Native Potting Mix for those species, or plant them into unimproved local soil.

Is it certified organic?

Yes. It is a certified organic product with no chemical additives, which is why the manure and compost in it are fully composted rather than raw. That makes it sound around fruit trees and vegetable beds, and it means you are adding genuine organic matter to your soil rather than a synthetic conditioner.

How much do I need?

Work on roughly one third planting mix to two thirds of the soil you dug out of the hole. For a shrub out of a 200 millimetre pot that is only a few litres. An advanced tree going into a large hole will take considerably more. Judge the quantity by the volume of the hole rather than the size of the plant.

Can I use it in pots?

It is not a potting mix and should not be used on its own in a container. The blend is designed to be diluted through garden soil, and used straight in a pot it holds too much water and settles badly. For containers, reach for a premium potting mix, or the native mix if you are potting natives.

Does it need to be watered in?

Yes. Water the plant well several hours before you plant it, then water thoroughly again once the hole is backfilled and the soil firmed down. That first deep watering settles the improved soil around the root ball and drives out air pockets. Keep the water up over the first few months while the roots establish.

View full details

Type: Garden Supplies

Enriched Planting Mix (AO Certified)

$21.95

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Uses in my Garden

Screening or Privacy
Shrubs
Rural Property Planting
Revegetation or Regeneration
Council or Civic Landscapes
Plant in Pots (or) Suitable for Pots

Callistemon citrinus 'Harkness' – Harkness Bottlebrush works in an:

Australian Native Garden – celebrates local plants with natural character.
Wildlife Garden – planting to attract birds, bees, and pollinators.
Coastal Garden – relaxed, seaside feel with hardy, textural plants.
Modern Garden – sleek, minimal, and design-led planting.
Low-maintenance Garden – resilient choices for easy care and year-round appeal.

Is Callistemon citrinus 'Harkness' – Harkness Bottlebrush Evergreen or Deciduous?

Callistemon citrinus 'Harkness' – Harkness Bottlebrush is an Evergreen (foliage year round) Tree

Mature Height & Width

Mature Height: 2m to 4m (approx.)

Mature Width: 1.5m to 2m

Callistemon citrinus 'Harkness' – Harkness Bottlebrush is expected to grow 40cm to 60cm per year (approx.).

Growth Rate of Callistemon citrinus 'Harkness' – Harkness Bottlebrush

Callistemon citrinus 'Harkness' – Harkness Bottlebrush is expected to grow 40cm to 60cm per year (approx.).

They are considered to have a:

Fast Growth Rate

Frost Tolerance & Ideal Climate to plant Callistemon citrinus 'Harkness' – Harkness Bottlebrush

Is Callistemon citrinus 'Harkness' – Harkness Bottlebrush frost tolerant?

Callistemon citrinus 'Harkness' – Harkness Bottlebrush is Frost Hardy – Survives heavy and frequent frost without damage.

Does Callistemon citrinus 'Harkness' – Harkness Bottlebrush Flower?

Callistemon citrinus ‘Harkness’ produces brilliant red bottlebrush flowers from late spring through summer, often with a lighter flush in autumn. These vivid, cylindrical blooms sit prominently at the ends of the branches, creating a bold and highly ornamental seasonal display.

Does Callistemon citrinus 'Harkness' – Harkness Bottlebrush flower?

Yes - Flowers

Flowering Period:

Summer
Spring
Sporadic

Flower Type:

Fluffy

Flower Colour:

Red

Is Callistemon citrinus 'Harkness' – Harkness Bottlebrush an Australian Native Tree?

Yes

Callistemon citrinus 'Harkness' – Harkness Bottlebrush is Native to Eastern Australia, particularly New South Wales and Victoria, where Callistemon citrinus naturally grows along streams, wetlands, and open forests.

What is the Wildlife Value of Callistemon citrinus 'Harkness' – Harkness Bottlebrush ?

Its nectar-rich flowers attract honeyeaters, native bees, butterflies and beneficial insects, while the dense, evergreen foliage provides excellent shelter for small birds. The long flowering period offers sustained support for pollinators throughout the warmer months.

How much Sunlight does Callistemon citrinus 'Harkness' – Harkness Bottlebrush need?

Callistemon citrinus 'Harkness' – Harkness Bottlebrush will thrive best in:

Full Sun

Preferred Soil?

Callistemon citrinus ‘Harkness’ performs best in well-drained sandy or loam soils and prefers slightly acidic to neutral conditions. It tolerates nutrient-poor soils but may struggle in heavy clay or waterlogged positions unless improved with organic matter and coarse material to increase drainage. Keep soil evenly moist during establishment, then reduce watering as it matures and develops excellent drought resilience.

Is Callistemon citrinus 'Harkness' – Harkness Bottlebrush Drought Tolerant?

Is Callistemon citrinus 'Harkness' – Harkness Bottlebrush Drought tolerant?

As a young tree it benefits from regular watering, but once established Callistemon ‘Harkness’ develops excellent drought tolerance. It performs reliably in hot, dry and coastal environments, maintaining strong flowering and dense foliage with minimal supplementary watering.

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How To Plant Your Callistemon citrinus 'Harkness' – Harkness Bottlebrush

Site: Choose a well-drained position in full sun to part shade with room for the canopy to develop.

Soil preparation: Enrich the planting area with quality compost and aged manure for a strong establishment phase.

Hole: Dig twice as wide as the root ball and the same depth.

Planting: Position level with the surrounding soil, backfill gently, firm in, then water deeply to settle the roots.

Recommended Planting Spacing For Your Callistemon citrinus 'Harkness' – Harkness Bottlebrush

Hedging and screening: 1 to 1.5 metres apart for a dense informal screen, or 80 centimetres apart for a tighter formal hedge.

Feature tree: 3 to 4 metres apart to allow the full canopy and form to develop.

Avenue planting: 3 metres apart for a uniform soft-textured avenue.

Callistemon citrinus 'Harkness' – Harkness Bottlebrush is expected to grow 40cm to 60cm per year (approx.).

Fast Growth Rate

Long Term Care For Your Callistemon citrinus 'Harkness' – Harkness Bottlebrush

Watering: Water deeply twice weekly through the first 12 months. Once established, this is drought tolerant and only needs a deep soak during extended dry periods.

Mulching: Apply a 5 to 7 centimetre layer of organic mulch over the root zone, keeping it 5 centimetres clear of the trunk.

Pruning: Tip prune in late winter and again in summer to build dense growth. For a formal hedge, light shaping two to three times a year keeps lines crisp.

Fertilising: Apply a slow-release native blend in early spring and again in autumn. Avoid high-phosphorus formulations as a precaution.

Pest and disease: Hardy against most pests and diseases. Occasional inspection in warm humid conditions is all that's needed.

Planting Your Callistemon citrinus 'Harkness' – Harkness Bottlebrush in Different Soil

Callistemon citrinus performs best in well-drained sandy loam or loam with a slightly acidic to neutral pH. Adaptable to a wide range of soils when drainage is improved with organic matter.

Sandy soil: Free-draining and ideal. Mulch well to maintain consistent moisture.

Clay soil: Improve drainage with gypsum and organic compost before planting.

Loam: The preferred soil for steady root development and consistent growth.

pH: Slightly acidic to neutral preferred. Mulch with composted leaf litter to maintain levels naturally.

Frequently Asked Questions

Frequently Asked Questions

Can Callistemon citrinus 'Harkness' thrive in pots? Yes, with proper drainage, it's suited for container planting.
What's the best time to prune? Late spring or after its main flowering season.