"Quiet achievers"

These tough plants are gems.
Sunday, 07 October 2018     

Plectranthus parviflorus Blue Spires

More and more I have become convinced that in gardening, as in life, it is the quiet achievers, which survive (indeed, flourish) in less-than-perfect environments that deserve the accolades, rather than the showy divas that demand perfect conditions and give up the ghost when they don't get them. We can seem to spend a lot of time (usually in vain) trying to please these temperamental types, whilst too often, 'quiet achiever' plants are taken for granted. 'They fill a gap', people will say, somewhat patronisingly and disparagingly. This week, I'd like to laud a couple of these plants and give them some time in the spotlight. I've recently been taking cuttings of them, so I can put them in other places in the garden to fill difficult spots.

Amongst the plant versions of quiet achievers, the genus Plectranthus has a host of suitable contenders. I wrote a blog a number of years ago about these very undemanding shrubby perennials that can grow in very ordinary soil and will flower well in dry shade, and they remain one of my favourite genera. Generally speaking, they bloom in late summer and autumn (for example, Plectranthus ecklonii, pictured at left), but there are a couple that seem to have a longer flowering period, giving them even extra value in the garden. They just uncomplainingly get on with filling challenging spots in the garden, bring welcome flowers and never cause any trouble! All they need is an occasional pruning and some general-purpose fertiliser when you are doing the rest of the garden.

One very old favourite is the South African Plectranthus saccatus (ht 1m), a low-growing shrub with jacaranda-blue, pouched blooms, which are larger than most other Plectranthus, appearing from December through to May. It has pretty, scalloped-edged leaves. It is an almost indestructible plant in the most inhospitable conditions of dry shade where it will form ribbons of colour as its cane-like stems scramble through other plants, or even climb up fences. It can be grown almost as a shrubby groundcover - or else clipped to a rounded shape. It grows well with cane and shrub Begonia plants, which also flower well in shade. It looks very effective grown with gold- or lime-coloured leaves, such as golden Duranta or with greenish-yellow flowers, such as those of Justicia brandegeeana 'Lutea'.

Another excellent South African Plectranthus that I have been growing in recent times, from a cutting from a friend, is Plectranthus zuluensis. This grows into a cushiony shrub about 1.5 m in height. It has bold, striking plumes of pale blue-mauve flowers that appear most of the year, with a brief respite in winter and early spring. The blooms have a resemblance to the flowers of Plectranthus ecklonii, pictured earlier in the blog. Plectranthus zuluensis will flourish in sun or shade and copes well with dryness. Mine grows with a free-flowering, dwarf pink Justicia carnea nearby; I am planting cuttings in other spots now that I have discovered what an accommodating plant it is!

Another very tolerant Plectranthus is a native Australian species, the name of which is something of a mystery: it seems likely that it could be P. parviflorus, P. graveolens or P. suaveolens. I refer to it as Plectranthus parviflorus but am happy to be corrected! These plants are apparently hard to tell apart by non-botanists! Mine was given to me by a friend as being one of the toughest plants she had ever grown. It gets to about 40 cm tall and forms a mound. It will grow in either full sun or full shade, plus in any moisture position ranging from a completely dry spot to a bog! It has aromatic, hairy leaves and seems to be covered in dainty spires of blue flowers basically all year round. At the moment, I am enjoying seeing its haze of lovely blooms juxtaposed with the lime-green bracts of Euphorbia corallioides in a shaded part of my garden. Elsewhere in the garden, it consorts prettily with a lilac-pink Pentas throughout summer and autumn. There is a lovely form with white-variegated leaves that is sold as P. parviflorus 'Blue Spires' (pictured at the start of the blog), which is similarly as forbearing of a range of conditions as the green-leaved version. The plants look good in a native Australian-style garden, a woodland area, a flowery border or a hanging basket. What a plant!

Another native Australian species is Plectranthus argentatus, one of my all-time favourite plants. It adds dainty spires of tiny autumn flowers in lilac calyces to the year-round beauty of its large plush-velvet leaves. It grows about 1m tall and tends to sprawl sideways a fair bit. It is one of the few silver-leafed plants to enjoy shade, including dry shade. It can form a broad pool of silver, which enhances any neighbouring leaves or flowers, but it looks particularly beautiful in association with white flowers, such as Japanese windflowers, cane and shrub Begonia plants, and Hydrangea.

All Plectranthus need to be replaced by new cuttings every so often as they get a bit straggly after a few years. They are easily propagated in spring or autumn.

 Reader Comments

1/7  Kerrie - 2104 (Zone:10 - Warm Temperate) Monday, 08 October 2018

Well thanks for this informative blog Dierdre! I"ve managed to I.D. a couple of mystery plants i loved the look of while out walking my dog & took a piece of to grow. Plectranthus argentatus & parviflorus. Great! I love those plants. Deirdre

2/7  Bren - 2540 (Zone:10 - Warm Temperate) Monday, 08 October 2018

Hebes. I have always thought Hebes to be rather unassuming plants, but I started collecting them (in a low key way) because my father in NZ used to have a large Hebe garden, and they evoked memories for me. Leaf shape, flower color and plant size all vary considerably, and they are really quite tough, and always look neat, though do require a modest amount of pruning. Oh! and regarding Plectranthus, I also love that genus! I do admire hebes but I have never had much luck growing them. I should try again! Deirdre

3/7  Anne - 4207 (Zone:10 - Warm Temperate) Monday, 08 October 2018

thanks for this interesting blog Deidre but I have a question that has been puzzling me. How do you tell the difference between Salvia and Plectranthus? They both look very very similar and some of mine may be one or the other. It"s a great question and I wish I knew the answer! They belong to the same plant family (Lamiaceae) and can look very similar. I have only learned the different ones by name and I don"t know how they are differentiated botanically. I will try to find out. Deirdre

4/7  Maureen - 2118 (Zone:10 - Warm Temperate) Tuesday, 09 October 2018

Great blog Deirdre especially as I love blue so now have a few to add. Will have to keep my eyes open on the trading table!! Will try to bring some in next time, Maureen! Deirdre

5/7  Sue - 2074 (Zone:10 - Warm Temperate) Wednesday, 10 October 2018

Thanks for the blog - they are great plants - I too love P.ecklonii which I have also in white and hopefully the pink, which hasn"t done so well as the others due to a harsh spot. The other one that is making a carpet in front of Clivias is P. foresti with its variegated leaves and white flowers in a very shady spot. Will look out for P. parviflorus. That plectranthus is a good one; I like the way it lights up a shaded area. Deirdre

6/7  Yvonne - 4570 (Zone:11B - Tropical) Friday, 26 October 2018

By Yvonne 4570 I have just found and joined your wonderful website. My favorite Plectranthus here in my Queensland garden is Plectranthus Australis which I believe originates from Sweden but does very well in the heat both in shade and part sun.The foliage is green and white and multiplies by rooting along the stems on the ground. Very hardy and a great ground cover. Thanks, Yvonne. That Plectranthus is a good one and makes a great groundcover! Deirdre

7/7  Gaynor - 5044 (Zone:10 - Mediteranean) Monday, 04 October 2021

I love plectranthus too (my favourite is probably Plectranthus parviflorus 'Blue Spires') and have noted their similarity to salvia. I once heard on Gardening Australia that salvias have a square stem, and some certainly do. Salvia discolour has a sticky round stem though. Most of them have distinctly smelly leaves, but so do some herbs. Plectranthus and salvia are similar and both easy to grow and propogate. Any luck with determining a way for us to tell the difference, Deidre?

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