Black Gastrolobium

Black Gastrolobium (Gastrolobium sericeum 'Black') is a compact Western Australian pea bush with jet-black flowers in spring and summer, a colour you rarely see in any garden. It makes a bushy shrub about 1m tall and 1.5m wide, with green leaves that are silky underneath. One caution first: some gastrolobiums are known as poison peas because of toxins that harm pets and livestock, so treat this plant the same way and keep it out of reach of animals that chew.

Why you'll love it

• Jet-black pea flowers. Rare, nearly black blooms open in spring and summer against green foliage, which makes the plant a conversation piece.
• Compact and bushy. At about 1m tall and 1.5m wide it fits a border or a mixed native bed without taking over.
• Nectar for birds. The flowers are rich in nectar, so birds visit it through the flowering season.
• Leaves built to save water. Silky hairs under the leaves help reduce water loss, one reason it copes with dry spells.
• A cut flower with a difference. The unusual flowers are used in floral art, so a few stems make a striking arrangement.

Where it works best

Sunny borders. Plant 1.2m apart so the shrubs just touch. Set it among silver or grey foliage plants, where the black flowers show best.

Native and wildlife gardens. It sits well with other Western Australian natives in free-draining beds, adding spring and summer nectar for birds.

Away from animals. Some of this genus carry toxins harmful to pets and livestock, so treat this one with the same care. Plant it where dogs, cats and livestock cannot reach it.

Growing Black Gastrolobium in Australia

Position and climate. Full sun in a sheltered, open spot. It comes from the south west of Western Australia, prefers a dry climate and tolerates light frost and drought once established. It will grow on the east coast, but in humid areas be extra careful about drainage.

Soil. Well-drained soil, whether sandy or clay-based as long as water does not sit. Mulch after planting to hold moisture and keep soil temperatures steady while young plants establish.

Water and feed. Water regularly while it establishes, then ease off. After pruning, apply a native slow release fertiliser.

Pruning. Prune in late spring, after new growth starts to mature. Follow with the native fertiliser to encourage a flush of fresh growth.

What to expect when it arrives

We sell Black Gastrolobium as tube stock, a young plant in an 80mm deep tube that establishes quickly, and in 140mm pots in packs of 10. Tubes are the value choice for a border planted in numbers, while the potted packs begin with more bulk. Plants arrive small and upright, so expect a modest shrub at first that fills out over its first seasons.

Tubes are supplied by our grower and are not always in stock. A sold out tube simply means the grower has none today, and the notify button on the page emails you the day it is available again.

Plants are delivered Australia wide, with delivery from $29.95. Every plant is covered by our 30 day healthy plant guarantee.

Plant care guides and related reading

• More Australian native plants
• Australian native shrubs
• Plants that attract birds
• A guide to rare Australian native plants

Common questions

Is it really poisonous?

Some gastrolobiums are known as poison peas because they contain toxins harmful to pets and livestock. Treat this plant as toxic and keep dogs, cats and livestock from chewing it.

Will it grow on the east coast?

Yes, though it prefers a dry climate. On the humid east coast give it full sun, sharp drainage and an open position so air can move through the foliage.

Are the flowers truly black?

They open as jet-black pea flowers in spring and summer, set against green leaves. Colour shows best against a pale or silver background.