Another tender plant today but an easy one to grow. Plectranthus are tender shrubs from Africa down and east to Australia and can be recognised by their square stems (a feature of the Lamiaceae family), opposite leaves set at 90 degrees to each pair, and the heads of tubular flowers. Many are short-day plants and only start flowering at the end of summer or into winter if they can be protected from frost. Some are (or were) popular as houseplants and are sometimes called Swedish ivy (for some odd reason). I used to use one in particular extensively in bedding and containers because of the attractive leaves but also because, like most plectranthus, it is ridiculously easy to root from cuttings in late summer. ‘Sascha’ (above) is a real gem and I even had some shoots that sported with no green at all and I grew those on. The undersides of the leaves are burgundy and the whole plant is fantastic.
But the most commonly sold is the comparatively nasty Plectanthus canina. Now I am not absolutely certain of this name and I am not 100% sure that it is even a plectranthus. But what I do know is that it is NOT Coleus canina as the pee-off plant is usually labelled! Unsuspecting buyers purchase this in the hope that it will keep cats off their garden but even if it works (and I am not sure it does having observed my cats) I would not buy it. It is tender, the flowers (which I totally accept are lovely) are only produced at the end of summer into winter, and it smell foul. Most plectranthus are variously aromatic, a feature I like, but this one is sticky, clammy and unpleasant. Some sources say it smells like cannabis but I make no comment about this!
Sometimes hybrid plectranthus appear in houseplant sections such as the ‘Mona Lisa’ above. Snap these up if you see them because plectranthus are easy to grow and propagate, suffering neglect in silence and forgiving less than perfect treatment.
But the most useful is possibly Plectranthus argentatus which can be grown from seed or cuttings. The large, felty, silvery grey leaves are produced on bushy plants that can easily elbow other plants out of the way in summer to make a bush 75cm high and wide. Late in summer it produces slender spires of small, white flowers that are no great shakes but nice enough.