There are hundreds of species within this genus but only a few are not tropical and therefore fully hardy in UK gardens. Those which are do however have a place in all of our gardens as they all produce a show in late summer or early autumn when most other garden plants have long finished their flowering season.
Indigofera are border shrubs which grow eventually to about 6ft in height. They can make freestanding shrubs in woodland settings but are best planted in groups of three or five for this purpose. They all have pea-like flowers in terminal racemes or spikes and attractive pinnate leaves which are alternate on the stems.
Indigofera grow best in full sun in reasonably fertile well drained soils. They thrive on acidic or moderately alkaline soils which is a plus. They can be prone to a little die back at the tips of the stems after cold winters but quickly rejuvenate sometimes from the base. The species we offer are however fully hardy.
There is one caveat! Indigofera are one of the very last plants to come into leaf in late spring so be patient with them and do not write them off too quickly.
This plant is most easily propagated from new growth in late spring.
I. ambylantha produces long racemes of pink flowers long into autumn.
I. heterantha has purple-pink flowers from summer well into autumn.
I. potaninii is perhaps our favourite at Burncoose with small pink flowers over three or four months.
We are experimenting in the nursery with other species including I. howellii and I. dielsiana which appear to have garden merit. The former is growing happily on a sunny bank at Caerhays and is one of those species which was popular and well known 50 years ago but has disappeared from cultivation.
With warmer summers and milder winters we are finding indigofera increasingly popular plants. We plan to offer more species in the coming years.