Leucadendron

( lew - kad - DEN - dron )

At-A-Glance Information

This genus of evergreen trees and shrubs, also called Conebush, includes species which need full sun and moderate water to perform well in the landscape. These plants hail from South Africa, where they are a prominent member of the fynbos ecoregion shrubland in the Western Cape and Eastern Cape areas. Leucadendron plants are dioecious; male and female flowers are borne on separate plants. Stems are great in both dried and fresh arrangements. Use these shrubs as eye-catching background foliage, in mixed beds and borders, in water-wise or drought-tolerant garden spaces, or simply as specimen plants in the ground or in containers. Take care when planting these shrubs in the landscape, as there are some sources that report that ingestion of plant parts is toxic to humans and animals.

Leucadendron Species and Varietals

The genus Leucadendron includes about 80 distinct species, and is a member of the plant family Protaceae. Plants in this genus are closely related to those in Protea, Leucospermum, Banksia, Grevillea, and Macadamia. The name of the genus was derived from the Latin word 'leucos', which means white, and 'dendron', meaning tree. Leucadendron grows best in USDA hardiness zones 9-11 or Sunset growing zones 16, 17, 20-24 and H1. To find your zone, click here: Zone Map.

Leucadendron argenteum (Silver Tree, Silver Leaf Tree, Witteboom, Silwerboom)
This tree is upright when young, and gnarling and twisted when mature. They can reach 40 feet tall and 25-30 feet wide, though they are typically about half that size in gardens. White silky leaves cover branches and are great for flower arranging. Flowers and fruit are inconspicuous. This species needs fast-draining soil that is alkaline. Smaller plants are great for containers (for about three or four years until they grow to big), and larger plants are wonderful for hillsides and sloped areas. The main cultivar of this species is 'More Silver', which has denser hairs on its foliage, making them strikingly silver-white. This species is considered invasive in California (United States).

Leucadendron coniferum (Dune Conebush, Dune Yellowbush, Duingeelbos)
These evergreen or deciduous shrubs can reach up to 13 feet tall and 5-6 feet wide. They produce yellow-green to chartreuse foliage. They can be pruned into trees, emerging from their roots as a single main stem. Female cones hold on to seeds until they are released after fire.

Leucadendron discolor (Piketberg Conebush, Rooitolbos)
This upright shrub grows to 4-8 feet tall and wide, with gray-green leaves. Red-centered gold inflorescences appear on the shrub in fall and wintertime. Cultivars of this species are listed and described below:

'Flame Tip'
4-8 feet tall and 4-5 feet wide with blue-grey foliage and white bracts with red centers.

'Inca Gold'
Butter-yellow flower bracts are tipped with red. To 4-6 feet tall and wide.

'Pom Pom'
Blue-grey leaves and yellow and red flower heads. To 6-8 feet tall.

Leucadendron galpinii (Galpins Conebush, Hairless Conebush, Silver Balls, Galpin's Coneflower, Silver Cone)
This shrub has an erect habit to 6-8 feet tall and 4-6 feet wide. Leaves are grayish green and male plants have yellow pom-pom flowers; females have grey, pink-tinged cones that are beautiful in fresh and dried arrangements. Cultivar 'Silver Cone' has narrow, green-grey foliage and brilliant silver-pink cones.

Leucadendron spp. Hybrids (Hybrid Leucadendron.
This is a group of shrubs that vary in shape, size and color. They are tolerant of frost and clay soils. The characteristics of each are listed in the descriptions below.

'Ebony'
With purple-black foliage and crimson red bracts. To 6 feet tall and 5 feet wide.

'Jester'
Leaves on this species are variegated with cream and green that are pink-flushed towards the tips of branches.

'Pisa'
Fast-growing hybrid that gets to 6 feet tall and 3-5 feet wide, with willowy grey-green leaves and silver cones.

'Red Gem'
This compact grower gets to 4 feet tall and 5 feet wide, and has red bracts and yellow cones.

'Safari Sunset'
8-10 feet tall and 6-8 feet wide. Red bracts appear in summertime and fade to yellow in the center by winter.

Leucadendron linifolium (Line-Leaf Conebush, Duineknoppiesbos, Knoppiesbos)
These shrubs are native to the Western Cape, South Africa and grow well in USDA hardiness zones 8a-11 or Sunset growing zones 16,17, and 20-24. They reach up to six and a half feet tall when mature with an upright, symmetrical growth habit. They produce whitish-pink flower inflorescences and prefer heavily sandy soil.

Caring for leucadendron

Plant your Leucadendron shrub in full sun (they need at least 6-8 hours of sun each day to perform well). Ensure that soil is well draining and has a pH of between 5.5 and 6.5 (acidic). If local soils are particularly poor in nutrients or do not drain well, make sure to amend the planting area with plenty of organic compost before installing. Apply a layer of mulch around the planting area to suppress weed growth, maintain consistent soil temperatures, and to increase soil moisture retention. Water regularly during their first year in the ground, and then reduce watering, allowing the soil to dry out between irrigation. They are considered drought-tolerant, and are commonly included in xeric landscapes and succulent beds that do not have formal irrigation systems.

Fertilize yearly in early springtime with an application of 2 inches of compost around the base of plants. Pull mulch back before applying, work the compost gently into the soil a bit, water it in, and then replace mulch. After flowering has faded, prune these shrubs to shape and remove dead or damaged growth and old flower spikes. Avoid pruning them back too heavily, as they do not reliably sprout from bare, woody, or leafless branches. Always leave some foliage on every stem cut. These plants can be damaged by cooler temperatures; they are hardy down to around 30 degrees. Anything lower will require some protection from frost, especially when they are young. These are long-lived perennial shrubs that typically last for between 10 and 20 years in the landscape before needing to be replaced.

Propagation

Leucadendron 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. To propagate your shrub, follow the instructions below:

Propagating Leucadendron 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 compost or other organic material. A good substrate for propagation of cuttings is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
In spring or early summertime, 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 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 four to six 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 Leucadendron 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. The best potting medium for seed germination is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
Harvest your seeds. The seed heads are left behind after flowers fade. Keep in mind that male and female flowers are on separate plants, and if you are to have your seeds be fertilized, you'll need to have both in close proximity. Cut the seed heads off the plant and place them in a paper bag, They'll continue to be released, and you can then gather them and remove their coverings and feathery attachments.
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 can take up to a year from sowing, and usually requires warm daytime temperatures and cool nighttime temperatures. 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.

A Leucadendron cone can contain anywhere from between 20 to 200 or more seeds.

Leucadendron seeds are large, nut-like hard kernels produced inside of woody cone-like structures. They often have a feathery attachment used for wind dispersal.

Problems and Pests

Certain species of Leucadendron are considered invasive in some regions; see the species descriptions above for more information. Check with local authorities before planting. Leucadendron shrubs are generally free of pest and disease issues. For information on commonly encountered pests and diseases in the home garden, consult the following pages:

Pests & Pest Management

Plant Issues