I tour a lot of gardens in the summer, and sometimes, you just keep noticing the same plant showing up in one beautiful garden after another. There’s something right about that plant.

This summer, the plant was golden Japanese spikenard or techincally Aralia cordata ‘Sun King’. This bright plant grows best in shady areas where it lights up the plants around it. While Japanese spikenard is a perennial, it has the heft of a small shrub. In ideal conditions with humus-rich soil, adequate water and dappled sun light, it can get 6 feet tall and wide. Truthfully, all the specimens I saw were in the 3 to 4 feet tall and wide range, which is a perfect size for many perennial beds. The chartreuse foliage, which I consider the main benefit of the plant, is brightest in spring and fall.

‘Sun King’ golden Japanese spikenard in Minnesota Sate Fair garden

Some websites list the plant as hardy to USDA Zone 4 (basically, St. Cloud and south in Minnesota) but other sites say it is hardy up to zone 3, which means it is worth a try in northern Minnesota

Sun King looks great with a variety of shade plants in different shades of green and purple: hosta, ferns, purple heucheras. The one photographed above was in the Minnesota State Fair garden of Hennepin Technical College. It was planted near other large, shade loving perennials, sun as Britt Marie Crawford ligularia, and it really stood out in the display — a great choice by the horticulture students at Hennepin Tech!

Spiknard has a white flower in late summer, which turns to a blue berry in fall that birds like. One thing to note about this plant is that it spreads via rhizomes, which means there will be suckers you will need to remove. If you like the idea of a shrub-like perennial but want to stay with natives in your yard, consider planting American spikenard (Aralia racemosa), a Minnesota native that has the same heft of Sun King but a more green color.

Aralia cordata ‘Sun King’ (Japanese spikenard ‘Sun King’)

Botanical name

Aralia cordata ‘Sun King’

Other names

Japanese spikenard ‘Sun King’, Udo ‘Sun King’

Genus

Aralia Aralia

Variety or Cultivar

‘Sun King’ _ ‘Sun King’ is an upright, clump-forming, deciduous perennial bearing pinnate leaves with ovate to elliptic, toothed, yellow-green leaflets and, in summer, upright spikes of tiny white flowers followed by purple-black fruit.

Foliage

Deciduous

Tree shape

Open branched, Spreading

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Colour

Flower

White in Summer

Yellow-green in Spring; Yellow-green in Summer

How to care

Watch out for

Specific pests

Aphids

Diseases

Generally disease-free.

General care

Pruning

Cut back to the ground after fruiting in autumn.

Propagation

Propagate by seed when ripe or root cuttings and suckers. This plant is difficult to propagate and is therefore expensive.

Propagation methods

Grafting, Seed, Root cuttings

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Where to grow

Aralia cordata ‘Sun King’ (Japanese spikenard ‘Sun King’) will reach a height of 1.2m and a spread of 1.2m after 2-5years.

Suggested uses

Architectural, Low Maintenance

Cultivation

Grow in fertile, humus-rich, neutral to acid, moist soil in partial shade. Tolerates full sun if soil is kept consistently moist.

Soil type

Clay, Loamy, Sandy

Soil drainage

Moisture-retentive, Moist but well-drained

Soil pH

Acid, Neutral

Light

Partial Shade

Aspect

East, West

Exposure

Sheltered

UK hardiness Note: We are working to update our ratings. Thanks for your patience.

Hardy (H4)

USDA zones

Zone 9, Zone 8, Zone 7, Zone 6, Zone 5, Zone 4, Zone 3

Defra’s Risk register #1

Plant name

Aralia cordata ‘Sun King’ (Japanese spikenard ‘Sun King’)

Common pest name

Leaf spot: ginseng; Leaf spot: ornamentals

Scientific pest name

Alternaria panax

Type

Fungus

Current status in UK

Absent

Likelihood to spread to UK (1 is very low – 5 is very high)

Impact (1 is very low – 5 is very high)

General biosecurity comments

A leaf spot disease; some commonly grown pot plants are hosts but main damage is to ginseng.

Defra’s Risk register #2

Aralia cordata ‘Sun King’ (Japanese spikenard ‘Sun King’)

pink wax scale; red was scale; ruby wax scale

Ceroplastes rubens

Insect

Absent

Based on its biology and low potential impact continued action on this pest in the UK would not be considered appropriate. It is likely to be of more concern to southern Member States of the EU; as it is an economic pest of citrus.

Defra’s Risk register #3

Aralia cordata ‘Sun King’ (Japanese spikenard ‘Sun King’)

; mango aphid

Aphis odinae

Insect

Absent

Aphid pest unlikely to survive in the UK and considered to be little or no pytosanitary risk.

About this section

Our plants are under greater threat than ever before. There is increasing movement of plants and other material traded from an increasing variety of sources. This increases the chances of exotic pests arriving with imported goods and travellers, as well as by natural means. Shoot is working with Defra to help members to do their part in preventing the introduction and spread of invasive risks.

Traveling or importing plants? Please read “Don’t risk it” advice here

Suspected outbreak?

Date updated: 7th March 2019 For more information visit: https://planthealthportal.defra.gov.uk/

Aralia cordata ‘Sun King’

This shrub is deciduous so it will lose all its leaves in autumn, then fresh new foliage appears again each spring.

  • Position: full sun to partial or full shade
  • Soil: fertile, humus-rich, moist soil
  • Rate of growth: average to fast
  • Flowering period: August and September
  • Hardiness: fully hardy
    Aralia is a great foliage plant that quickly forms a handsome mound of large, golden-green (or lime-coloured in shadier spots) leaves, which are held on rich mahogany stems. The tropical-looking foliage is reason enough to choose this plant, as it will add structure and form as well as colour to the planting scheme. In late summer however, tall flowerspikes appear, smothered in rounded clusters of tiny white flowers, and later rounded black (inedible) fruit – a bonus!
  • Garden care: Keep plants growing in full sun really well watered. Protect from strong winds. Remove suckers as soon as they appear, cutting them back to the base of the plant. In late winter or early-spring remove any misplaced, diseased or crossing branches

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