The other day I acquired a plant of Diplacus aurantiacus, a name that might be unfamiliar because the plant  is still better known by its previous name of Mimulus aurantiacus. I first knew this plant when I was a student at Kew, when the plant was used extensively for summer bedding, especially in containers. The rather rangy stems and sticky leaves made a loose bush and it flowered all summer with blooms in shades of apricot, tangerine or rusty red, depending on variety. Then, years later, I saw it growing wild in dry landscapes in California and have grown it, on and off, since then. It is good to have it again.

This shrubby mimulus is one of those awkward plants that, in the UK and Irish climate, does not sit happily in any category. It may survive outside in coastal areas if the soil is dry and it is neither quite a shrub when grown as bedding, as an annual, nor herbaceous. But the long succession of beautiful flowers compensates for this. It definitely does not want the same conditions as most mimulus we grow in the garden which tend to prefer constant moisture.

A note on classification: this used to be in the family that we all knew and loved as Scrophulariaceae – I say loved but when it came to engraving plant labels it was annoying that this was the commonly used family name with the most letters! But now mimulus and diplacus are in the Phrymaceae. The distinction between this and the Plantaginaceae (which is the new name for the scrophs) is that the calyx has five lobes, the stigma is bilobed and sensitive – the two parts closing together after pollen has been applied – and the shape of the seed capsule.

As to the new (ish) genus of diplacus, I can cope with that because of the fact that it is shrubby, unlike the rest of the mimulus.

You may be able to buy seeds, which need chilling, after sowing, (stratification) before they will germinate but you can also take tip cuttings in summer to propagate your plant, especially for named cultivars that will vary from seed. The plant will grow to about 60cm high, maybe more if it acts as a perennial, and benefits from a light pruning in spring to keep it compact. It is drought tolerant and, where they fly around, humming birds are attracted to the flowers. I have never tested the hardiness but it should tolerate a few degrees of frost as long as the soil is well drained.

Geoff’s rating

9/10

Garden rating

7/10

Diplacus aurantiacus, diplacus propagation, Mimulus aurantiacus, Phrymaceae