Banksia

( BANK - see - uh )

At-A-Glance Information

This genus of evergreen wild shrubs and some trees needs full sun and moderate water to perform well in the landscape. The flowers will attract birds and beneficial insects to the garden. Banksia species are native to Australia. White, orange, yellow or red blooms 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, adding between 6 inches and a foot to their size each year. Use Banksia in drought-tolerant or desert landscapes, in mixed beds and borders, or simply as specimens for their striking flowers and foliage. Take care when planting these trees and shrubs in the landscape, as plant parts can be toxic to pets if ingested.

Banksia Species and Varietals

The genus Banksia is a member of the plant family Proteaceae (subfamily Greveilleoideae), and includes around 170 species. Species in this genus are closely related to Grevillea, Macadamia, and Hakea. 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 USDA hardiness zones 8-11 or Sunset growing zones 15-24 and H1. To find your zone, click here: Zone Map.

Banksia ashbyi (Orange Banksia, Ashby's Banksia)
This shrub reaches 12 feet tall and just as wide, if not a little wider. Leaves are greyish-green and serrated. Flower spikes are bright orange and appear in summertime at branch tips, held above the foliage. This species is commonly used as an informal screen or hedge plant and takes shearing well. A good choice for coastal gardens. Some subspecies are handsome compact growers.

Banksia baxteri (Bird's Nest Banksia, Baxter's Banksia)
This shrub has an erect, spreading habit and reaches 6-10 feet tall and just as wide. Leaves are green and have triangular lobes. Flowers, which bloom profusely, are yellow-green and dome-shaped. This species can do well in coastal gardens if provided with some added protection from drying, salty winds.

Banksia ericifolia (Heath Banksia, Heath-Leaved Banksia, Lantern 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. This species can take coastal conditions in stride. Cultivars include 'Giant Candles' (with large flower spikes), 'Roller Coaster' (a prostrate, spreading form), 'Little Eric' (to 6 feet tall), 'Bronzed Aussie' (with bronze new foliage), 'Limelight' (with bright lime-green foliage on a slow-growing shrub), 'Golden Girl' (compact, blue-grey foliage and gold flowers), and 'Dwarf Red' (compact form with yellow-orange-brown blooms). This species is considered invasive in some parts of the world, notably in the UK, Hawai'i and South Africa.

Banksia grandis (Bull Banksia, Giant 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 that are sought after for crafting and carving. 'Little Bull Banksia' is a dwarf form of this species that reaches to 3-6 feet tall when mature.

Banksia integrifolia (Coast Banksia, Coast Honeysuckle, White Banksia, White Bottlebrush)
This species forms a tree that reaches to 30-60 feet tall and 15-30 feet wide at maturity. 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 in the genus.

Banksia praemorsa (Cut-Leaf Banksia)
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 (pictured). This species appreciates well-draining soil and can take windy, coast conditions. Great as a screening or hedge plant.

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

Banksia speciosa (Showy Banksia, Ricrac Banksia)
This shrub reaches up to 12-20 feet tall and 10-15 feet wide at maturity. Foliage is toothed and green to blue-green, and white flower cones open to yellow. This species blooms in summer and fall in its native range. This species is an emerging invasive in some regions, particularly in South Africa.

Banksia spinulosa (Hairpin Banksia, Golden Candlesticks, Hill 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 Banksia

Take care when planting these trees and shrubs in the landscape, as plant parts can be toxic to pets if ingested. Banksia shrubs and trees prefer to be planted 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

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.
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.
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.
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

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.
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.
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.
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.
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.