Known as The Everlasting Pea, this is the perennial form of the annual sweet pea which as you can see from the images, looks very similar to the annual climbing pea. Its Latin name is Lathyrus latifolius, compared to the annual sweet pea which is called Lathyrus odoratus, and the Latin names describe the essential differences between the two peas; the everlasting pea is not scented.
In all other ways the Everlasting Pea makes up for its shortfall in being an attractive shrubby climber, easy to grow from seed with many delicate flowers usually in soft pastel shades, blues and purples. There is also a pure white variety called "White Pearl".
Annual Sweet Peas are lovely, but they are time consuming to seed and grow. The Everlasting Pea does need attention in the summer to ensure it does not dry out and to check the tendrils so it does not become too tangled, but it is not as time consuming as the annual variety, and will return reliably each year.
The Everlasting Pea will flower best grown in full sun, although tolerant of some shade. It grows in a very similar way to the annual sweet pea clinging on with tendrils and it will climb or scramble over and obelisk, trellis or adjacent shrubs. It is very hardy, H7 which means it will survive the most severe of winters. It is not particular about the soil type, acidic or alkaline, clay, etc, although it will grow best in fertile soil with plenty of moisture. Ensuring it has plenty of moisture will help to fend off powdery mildew.
With the exception of cutting back the Pea in the autumn, the growing conditions for the annual and Everlasting Pea are really the same.
It is deciduous and should be cut back to ground level in the autumn.
There is also a variety called Lathyrus grandiflorus, which you may want to give a miss as it is vigorous, bordering on invasive, whereas L. latifolius is well behaved.