Pyncinostachys urticifolia produces the most beautiful cobalt blue flowers in autumn and early winter.
Despite having the most amazing cobalt blue flowers and being a versatile garden shrub, Pycnostachys urticifolia (Blue Boys) is not well known nor more widely grown. Although a little frost tender, if planted in a sheltered spot it will survive the Gauteng winters with little mishap, much like Plectranthus (Spurflowers) do.
Family:               LAMIACEAE        (Mint family) Name Derivation:
  • Pycnostachys from the Greek words ‘pyknos’ and ‘stachos’ and translates to ‘dense spike’ or ‘dense corn ear’, referring to the flower spike.
  • urticifolia – having leaves like those of a nettle (Urticea).
Common Names:          Blue Boys (Eng), ystervarksalie (Afr), gogodza (Ven), amadata and unkungwini (Zul).
Form:                                A medium sized, many branched, upright or rounded shrub. Size:                                   1 – 2 m by 1 – 1.5 m. Flowers:
  • Stunning cobalt blue flowers are borne on rounded, pyramid like flower spikes.
  • Flowers open in rows around the cone together, starting from the base of the spike and progressively opening closer to the terminal point.
  • Usually two or three rows of flowers open at any time, with more showing their colour before opening.
  • As the older flowers die and drop off, they leave reddish spines at their base on the cone.
  • The spiky ‘cones’ remain on the plant long after the flowers have finished and give rise to the Afrikaans name ‘ystervarksalie’ (Porcupine Salvia).
  • New flower spikes constantly form during the flowering period.
The flower spikes of Pyncinostachys urticifolia , Blue Boys, continue to grow longer as the flowering season progresses.
Pyncinostachys urticifolia grows equally well in sun or partial shade, but tends to be a bit more compact in sun.
Colour:                               Cobalt blue, rarely white. Flowering Months:          Mar to Aug, but frost may stop the flowering. Fragrance:                        Crushed leaves are aromatic. Foliage:
  • Evergreen to partly deciduous.
  • Has simple, green, oval leaves with scalloped margins.
Thorns:                          No thorns.
  • Seeds are contained within a capsule within the calyx.
  • Stems are sparsely hairy.           
In the Garden:
  • Pycnostachys urticifolia is an attractive plant suitable for the back of informal borders or beneath trees.
  • It is frost tender and may be cut back if exposed to too much cold.
  • It may be planted individually but looks best when planted in groups of three or more plants.
  • It is equally at home in full sun or dappled shade beneath trees, but tends to be smaller and more compact in full sun.
  • It is a good pot plant.
  • A wildlife friendly shrub, attracting insects, bees and butterflies.
  • A quick growing shrub, flowering within the first year of been planted out.
These Pycnostachys urticifolia plants, photographed in the Walter Sisulu Botanical Gardens, were growing in the dappled shade of trees.
Pycnostachys urticifolia has simple, green, oval leaves with scalloped margins.
Soil Needs                        Plant in ordinary garden soil with compost, 2:3:2 and bonemeal. Care:
  • A low maintenance plant.
  • Mulch with a layer of compost once or twice a year and feed with organic 3:2:3 and bonemeal.
  • Plant in a sheltered position.
  • Cut back in spring after the threat of frost is past.
 Cold Hardiness               Semi-tender. Water Requirements:
  • Likes regular water in summer but will endure some drought.
Light Requirements:        Full sun or partial shade.
Roots:                                  The roots are not aggressive. Birds:
  • Insect-eating birds are attracted to the insects that eat the leaves.
Insects and Butterflies:
  • Flowers are visited by many insects and adult butterflies.
  • Host plant to the larva of the Gaudy Commodore
  • Also larval host of 1 moth species.
  • No records of being used as a medicine.
Pycnostachys urticifolia, Blue Boys is a host plant for the Gaudy Commodore (Precis octavia sesamus).
Poisonous:                       Not poisonous. Notes of interest:
  • Pycnostachys urticifolia is grown in gardens in the USA where it is called witches hat.
  • Although looking impossible to pronounce, it is in fact quite easy, ‘Pick no stack us’.
Natural Distribution:
  • Occurs naturally in the EC, KZN, Swa, M, L, G and Zim.
  • North of southern Africa its range extends into Malawi.
Natural Habitat:
  • In bushveld, grasslands and in forest margins.
  • Often in marshy conditions or along stream banks.

© Malcolm Dee Hepplewhite & Witkoppen Wildflower Nursery, (Text and Photographs) 2012 & 2018