The Sandpaper Vine.
Petrea volubilis is it’s proper name, the most important garden species of more than 30 other species of the Genus. This climber belongs to the verbena family and comes from Mexico and Central America and was named after Lord Robert James Petrie 1713 – 1743 an impassioned horticulturist who developed Thorndon Park in Essex, UK. The common name alludes to the sandpapery feel of the leaves which are hard and rough when they are mature. Another common name is Purple Wreath because of the wreath-like sprays of purple flowers.
Growing in its natural woodland areas as a climber it can reach 12metres in height but it doesn’t grow this big in NZ. Some references say that it is a vigorous grower but I find it has only medium vigour probably because it is a bit cool for it here. If it has nothing to climb on it tends to grow as a bushy shrub which can be trimmed back to make it the right size for your position. They can be made into a standard very easily by tying the climbing stem up a stake until the required height is reached then prune the growing tips to make them branch. Try a plant in a hanging basket also. You can get a lovely weeping effect by a bit of training of the branches. Petreas are quite tolerant of a range of soils from quite moist to dry (once they are established). Frost free sites are best but light frosts will only cause minor damage. It will grow in coastal positions but give it some protection.
Flowering starts in early spring and can carry on until the autumn. The flowers are very spectacular and appear on racemes up to 30cm long. It is mostly the purple/blue calyx of each flower that is noticed as the blue flower itself is quite small and lasts only a few days before it drops. The calyxes persist for quite a long time, gradually fading to grey before they drop. There is a cultivar called ‘albiflora’ which is nearly white but I haven’t seen it available in this country.
Indians of the Amazon, Guyana and Brazil used the sap for the treatment of burns, wounds and abcesses.
Propagation is by cuttings, air layers and sometimes root cuttings. I haven’t seen seed in NZ.
The plants generally have no pests and diseases though sometimes aphids can congregate on new growths.
Not many plants give such wonderful blue colours in the garden over such a long time. As it is so easy to control why not try one in your little corner of this world. I think you will love it.