Banksia

( BANK - see - uh )

At-A-Glance Information

This genus of evergreen wild shrubs and some trees needs full sun and moderate water. They will attract birds and beneficial insects to your garden. Banksia is native to Australia. Flowers on these plants appear in dense cylindrical clusters and are followed by long-lasting seed pods. The blossoms are rich in nectar and are wonderful (and quite dramatic) in cut flower arrangements. These shrubs and trees are moderate growers. 

Banksia Species and Varietals

The genus Banksia is a member of the plant family Proteaceae (subfamily Greveilleoideae), and includes around 170 species. The genus was named for Sir Joseph Banks, the naturalist and botanist who first collected specimens of the plants in the 1770s. The best growing zones for Banksia are 15-24 and H1. To find your zone, click here: Zone Map.

Banksia ashbyi (Orange Banksia)
This shrub reaches 12 feet tall and just as wide, if not more. Leaves are greyish-green and are serrated. Flower spikes are bright orange and appear in summertime at branch tips. Great as an informal screen or hedge plant; takes shearing well. Great for coastal gardens. Dwarf varieties are available.

Banksia baxteri (Bird's Nest Banksia)
This shrub has an erect, spreading habit and reaches 6-10 feet tall and just as wide. Leaves have triangular lobes and flowers, which bloom profusely, are yellow-green and dome-shaped. Great on coastlines if provided with protection from salty winds.

​Banksia ericifolia (Heath Banksia)
This shrub has a bushy habit and reaches 10-20 feet tall and spreads to 6-12 feet wide. Flowers are orange-red and leaves are needlelike. Can take coastal conditions. Varieties exist that are dwarf (reaching only 6 feet tall).

Banksia grandis (Bull Banksia)
This species takes the form of a tree, reaching 15-25 feet tall and 8-10 feet wide. Leaves are dark green and have deep lobes. Flower spikes are creamy white and after their spring bloom, develop into hard cones (pictured) that are sought after for carving. For small gardens, dwarf forms are available that reach only 6 feet tall.

Banksia integrifolia (Coast Banksia)
This species is a tree that reaches 30-60 feet tall and 15-30 feet wide. Flowers are pale yellow and appear in fall, winter and springtime. Great for coastal gardens, this species is considered to be one of the more fast-growing of the genus.

Banksia praemorsa
This shrub has a dense, upright habit and reaches 10-12 feet tall and 6 feet wide. Flowers are wine-red and bloom in winter, spring or summertime. A variety is offered with yellow blooms. Likes well-draining soil and can take windy, coast conditions. Great for screen.

Banksia prionotes (Acorn Bankia)
This species takes the form of a shrub or small tree and reaches 9-25 feet tall and just as wide. Leaves are dark green and are deeply toothed and flower spikes are orange, opening from cream-colored buds.

Banksia speciosa (Showy Banksia)
This shrub grows 12-20 feet tall and 10-15 feet wide and has toothed leaves and white flower cones that open to yellow in summer and fall. 

Banksia spinulosa (Hairpin Banksia)
This species takes the form of a smaller shrub, growing to around 2-4 feet tall and 4-5 feet wide. Medium-green leaves and golden-yellow to orange flowers. Easy to grow and care for. Variety 'Schnapper Point' has flowers in rich yellow and red.

Caring for and pruning Banksia Trees

Banksia shrubs and trees prefer to be planed in full sun to partial shade, and in soil that is well-draining. They should be receiving direct sun for at least 6 hours per day for best performance. Ensure that the plants are protected from strong afternoon sun, especially in hot climates. This type of exposure can cause leaf scorching, or sunburn. Banksias are great options for hillside gardens, and for planting in raised beds or containers where their specific soil needs can be met. Sandy soils are best, with an acidic to neutral pH (on average between 5.5 and 6.5). These plants adapt well to nutrient-poor soils, as this is what they grow in in their native ranges. Amend heavy (clay) soils with gravel and sand or perlite and shredded fir bark before planting. Although these are drought-tolerant once mature, they will need regular waterings after they are installed as they establish their root systems. Once established, water deeply but infrequently, and allow the soil to dry out between waterings. Overwatering or standing water around roots can cause issues with root rot.

These trees and shrubs are well-adapted to poor soils, and do not generally require fertilization. If growth is slow or leaves appear pale, a slow-release, low-phosphorus fertilizer can be applied in springtime. Avoid phosphorus fertilizers. Banksias can be pruned as needed to maintain shape and size, and to remove dead, dying, damaged, crossing or diseased branches. Banksias can tolerate hard prunings if it is completely necessary, but avoid cutting into old wood, as the plant may not regenerate from old stems. Tree species really do not need much in the way of special prunings, but shrubs can be trimmed back to the current season's growth if needed to rejuvenate.

Propagation

Banksia can be propagated either by using cuttings or from seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the cutting method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant. Trees and shrubs grown from seed can take 2-3  years to flower and 5-6 years to reach full height, on average. To propagate your tree or shrub, follow the instructions below:

Propagating Banksia by Cutting
  1. Gather your materials. You'll need a clean, sanitized, sharp pair of garden shears, rooting hormone, a pencil, and a 3-inch pot filled with well-draining propagation mix or other organic material.
  2. In spring, summertime, or early fall, choose the plant that you'd like to propagate. Ensure that this plant has had a good watering the night before, as this will improve the chances your cutting will take root. Cut one or more 6 inch semi-hardwood portion(s) of the end of a non-blooming branch and strip the leaves off of the lower half. Make a hole in your planting medium by pushing your pencil into the soil. Dip the end of the stem in rooting hormone, and plant it in your pot. Fill in soil around the cutting to support it, but do not pack it down too much.
  3. Moisten with water, and ensure that the pot has good drainage. Your pot should be kept in warm, sunny conditions indoors (and not in direct sunlight). Water whenever your soil is dry under the top layer. After about eight weeks have passed, your cutting should be rooted. When you notice new growth, you'll know you have roots. 
  4. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring, when you can transplant it to its new home. Ensure that the last frost of the year has occurred before doing this, as it can seriously damage your new shrub.

Propagating Banksia by Seed
  1. Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand. You will also, after a few weeks, need individual 3-inch pots for each seedling that grows. 
  2. Harvest your seeds. Seeds of Banksia plants are contained within the female cones produced by the plant. In nature, these cones open in response to high temperatures, like the ones experienced during a wildfire. To mimic these conditions, place the unopened cones in an oven set to between 215 and 300 degrees Fahrenheit, and bake for about an hour. 
  3. Place your seeds in lukewarm water for 24 hours. Viable seeds will sink to the bottom, and non-viable seeds will float to the top. You can discard any seeds that float. After this treatment, set the seeds out to dry in a cool, dark, dry place. 
  4. Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes about 14 days from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
  5. Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.
Banksia seeds are stored within cones produced by the plants, and they are triggered to release seeds in response to high heat.
Banksia seeds removed from the cones.

Problems and Pests

Banksia plants are generally resistant to pests and disease, though they should be monitored for the following issues:
  • Aphids
  • Scale Insects
  • Flower Blight
  • Shoot Tip Blight
  • Black Spot
  • Cinnamon Fungus
For more information on these pests and diseases, see the following links:
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Gallery

Banksia spinulosa 'Scnhapper Point'.
Some species of Banksia form small trees or stately shrubs that can become focal points in smaller gardens.
Banksia does well in beds with other low water-use plants.
Banksia trees and shrubs will attract birds and beneficial insects to your garden.
Banksia flowers are interesting, and are commonly harvested to be added to fresh cut flower arrangements.
Banksia integrifolia trees make wonderful screening plants for homes and businesses.

Videos

Learn about some of the popular Banksia varieties.
Visit this garden featuring Banksias.
All about Coastal Banksia.
How to grow and care for Banksia plants.
Crafting with Banksia pods.
How to use these Australian native plants in your garden.

Resources

How to Grow a Banksia Tree
How to Grow Beautiful Banksia
Banksia Information - Learn How to Grow Banksia Plants
Banksia Grow Guide
The Propagation of Banksia
Wikipedia: Banksia
The New Sunset Western Garden Book: The Ultimate Gardening Guide (2012) - Pages 187 - 188, Banksia
If you have any questions, comments, concerns, or photos you’d like to add to the gallery, please let me know by sending me a message using the button below!
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