"Shady characters: Plectranthus"

The many types of Plectranthus provide some of my favourite autumn flowers for shady spots.
Sunday, 07 March 2021     

A white version of Plectranthus ecklonii

Some of my very favourite plants for early autumn belong to the genus Plectranthus. Traditionally regarded as daggy plants only suited to the school fete plant stall, they are now given the respect they deserve.Though some do flower during other times of the year, early autumn is when they seem to be at their very best. Belonging to the mint family (Lamiaceae), they hail from warm temperate to tropical areas of the world (especially South Africa) and they can bring flowers and often attractive leaves into shadier parts of the garden under trees in very ordinary soil where many plants do not thrive. They grow quickly and are tolerant of drought and root competition. They are disease and pest free. They also suit coastal gardens. What more could we ask of a plant?

Their two-lipped, often whiskered flowers are usually held on spikes above the foliage, which is generally soft and aromatic; some species have shiny, succulent leaves. Of the 350 or so species, there is a wide range of growth habits, from groundcovers to tall shrubby perennials. They are frost sensitive to varying degrees but cope well with Sydney winters. I generally prune my specimens back in mid-August, when they are also given some fertiliser. I replace them every few years from cuttings, which strike easily.

One of the tallest and showiest is Plectranthus ecklonii (ht 1.5 - 2 m) with its fuzz of large purple-blue feathers of flowers with pronounced stamens. It is one of the earliest types to flower, often beginning its long period of bloom in February. It mixes effortlessly with shade-loving plants with pink, white or burgundy flowers in bloom at this time, such as cane begonias, Japanese windflowers and Justicia carnea. Superb white and pastel pink forms of Plectranthus ecklonii are also around, offering great potential for attractive autumn flower schemes in shadier parts of the garden. The misty, lacy fretwork of their flowers offers a contrast to bolder tropical blooms such as the huge pink or white angel's trumpets (Brugmansia species and cultivars), which continue to have flushes of flowers in autumn. They also mingle well with Camellia sasanqua or the ageing blooms of mop-headed Hydrangea.

Plectranthus zuluensis (ht 1.5 m) also has large flower-heads, which are a soft powder-blue colour. This is one of the species that flowers in flushes for a long time in Sydney gardens (from spring to early winter), but it is at its peak in autumn. Another of these floriferous plants is the lower-growing, shrubby Plectranthus saccatus (ht 1 m). which has jacaranda-blue, pouched blooms. It is an almost indestructible plant in the most inhospitable conditions of dry shade; it looks particularly attractive with lime-coloured leaves. It blooms from mid-summer till the end of autumn.

Hybrid plants sold as 'Cape Angels' result from a cross between Plectranthus saccatus and Plectranthus hilliardiae to form compact shrubs about 60-80 cm tall, with white, pink, purple and cerise-purple flowered forms, which are easily grown little shrubs which bloom over a long period. The well-known 'Mona Lavender' (ht 40-60 cm) results from the same cross. Smothered with a mass of prominent, upright lavender blue flower spikes set amongst purple-backed leaves, it is an eye-catching addition to the clan. These are all suitable for growing in a pot.

The silver plectranthus (Plectranthus argentatus, ht 1 m), is an Australian rainforest plant which is mainly grown for its large plush-velvet leaves, rather than its dainty lilac flowers, though they are rather pretty. It is one of the few silver-leafed plants to enjoy shade, and it looks beautiful in association with white flowers, such as windflowers or the lovely purple and silver foliage of Strobilanthes dyeriana (pictured at left). It will also grow very successfully in dry, sunny positions. A groundcover Plectranthus cultivar known as 'Nicoletta' has similar foliage, but it doesn't appear to be related to Plectranthus argentatus.

Also at groundcover level, Plectranthus ciliatus, ht 30-40 cm has an autumn veil of long spires of dainty lilac-tinged flowers across its purple-veined and purple-backed leaves. It will form an excellent carpet in the most uncongenial shady places under trees or shrubs, and is stunning when in full bloom. 'Nico' is an exceptional groundcover Plectranthus similar to this type, with larger and more deeply-veined leaves, and apparently derived from a different species. Another groundcover is Plectranthus verticillatus, sometimes called Swedish ivy, which grows to form a lush rug of shiny green scallop-shell leaves and has a froth of white flowers in autumn. All the groundcover types make excellent hanging basket subjects.

An excellent reference book on these plants is The South African Plectranthus by Ernst van Jaarsveld. For more information on the different sorts I grow, follow this link.They are such useful plants, and there are so many more species and cultivars which are grown overseas not yet available to us, including sumptuous gold-variegated leaf versions!

 Reader Comments

1/11  Alida - 4566 (Zone:11A - Sub-tropical) Thursday, 02 April 2009

They are so welcome this time of the year - they make my garden. I cant have enough of them!

2/11  Margaret - 2122 (Zone:10 - Warm Temperate) Thursday, 02 April 2009

love plectranthus - the white flowered one looks especially great in shady corners. I like them in all their forms, and it is hard to pick a favourite! Margaret

3/11  Kathryn - 2119 (Zone:10 - Warm Temperate) Thursday, 02 April 2009

Plectranthus have thrived in my shady garden, despite long periods of neglect. Love them all, especially Ciliatus and Mona Lavender, as I find the purple undersides of their foliage amazing!

4/11  Jan - 2072 (Zone:10 - Warm Temperate) Tuesday, 21 April 2009

Congratulations on your photographs and so exciting for members to just click on each photo and see a large version - you make it so easy. I have a mona lavendar in a pot and want to know when it stops flowering so I can trim it. So far it flowers all year round.

Thanks, Jan. You could probably just trim back a little bit of 'Mona Lavender' every so often. I tend to do all mine in early August. Deirdre

5/11  Bren - 2540 (Zone:10 - Warm Temperate) Monday, 08 March 2021

Yes, I have a number of Plectranthus; such reliable plants! Coleus (which later become Solenostemon) has also been reclassified as Plectranthus, but I think even this might have changed by now. Sometimes it seems that while plant classification based on DNA and other modern techniques is more accurate, it doesn't make the process of classification any simpler! It is all very confusing! I still think of them just as coleus! Deirdre

6/11  Rob - 3163 (Zone:10 - Mediteranean) Monday, 08 March 2021

I was given a cutting of the baby pink form of P ecklonii by an elderly lady whose garden I used to help with. (Who else but elderly ladies have saved so many of our 'out of favour' plants!) It's the most 'pink' of pink flowering plants you could imagine. Absolutely stunning! And not so brutish as the more common purple variety. It is gorgeous that pink one, The white is also lovely. Deirdre

7/11  Tracey - 2099 (Zone:10 - Warm Temperate) Monday, 08 March 2021

I have terrible trouble with caterpillars on plectranthus, which is frustrating because most of my garden is shady and dry and they would be very useful! Maybe try the spray Success? It is an organic sort of spray for caterpillars. Deirdre

8/11  Pam - 2159 (Zone:10 - Warm Temperate) Monday, 08 March 2021

Plectranthus put on wonderful displays of gentle colour. I have collected quite a few from generous donations of flowering stems at local garden club meetings over the years. I have even 'planted' stem cuttings of P. ecklonii between plants such as Camellia sasanquas, and many have grown - the purple-blue looks good with the white and pink of the camellias. A lovely combination. Garden clubs are the best places to get these sorts of plants! Deirdre

9/11  Sue - 2074 (Zone:10 - Warm Temperate) Monday, 08 March 2021

The wind flowers and the plectranthus make a lovely combination. Am enjoying mine and hoping I can take a cutting of the pink one, they don't seem as robust as the white and purple. My delight at the moment is Plectranthus oertendahlii which has grown to a nice big patch and is presently in flower - had to find it's name in your plant file. Thanks Deidre as I first saw it on this site. The pink does seem more sensitive to too much sun and not as strong as the others. I take a new cuttings every few years to keep them all going as they get woody over time. Great to hear you have had good success with P oertendahlii in your garden! Deirdre

10/11  Gaynor - 5044 (Zone:10 - Mediteranean) Monday, 08 March 2021

I was looking for something which could survive in deep shade and then full sun (on the southern side of a building). A rare plant was needed and I discovered 'plectranthus' as a result of this search. It is a very admired plant and it is easy to propogate. Anyone who admires it, is given a piece. I will look up the botanical name, especially now that I know there are so many different ones. Salvias, agastache and plectranthus - similar, but all beautiful. They are all great plants for Sydney. Deirdre

11/11  Hanni - 2134 (Zone:10 - Warm Temperate) Friday, 12 March 2021

Thank you, Deirdre, for another one of your informative blogs. Now I learned, that some of my salvias are actually Plectranthus! Who invented this name? What a tongue breaker! Isnt there a nice common name for these beautiful plants? I got mine from cuttings - they grow so well in my shady garden and really put on a big show now. I have seen 'spurflower' used for Plectranthus but I don't think it is widely known. Plectranthus and Salvia belong to the same broad Lamiaceae family, as they have characteristics in common, Can be confusing at times! Deirdre

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