Quiet achievers

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.

Purple Plectranthus ecklonii with Anemone Bowles Pink in late summer and early autumn

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.

Plectranthus saccatus in the Sydney garden of Alida Gray

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'.

Plectranthus zuluensis with Justicia carnea

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!

Plectranthus species, possibly P. parviflorus

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!

Silvery Plectranthus argentatus (left) with Strobilanthes dyeriana

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.