Sour Grapes Penstemon

Sour Grapes Penstemon (Penstemon 'Sour Grapes') is an upright, bushy perennial that grows about 70cm tall and 50 to 70cm wide. It is a heritage variety that carries the Royal Horticultural Society's Award of Garden Merit, with large tubular flowers from summer into autumn. The colour is blue-purple along the tube, shading to lilac-purple at the mouth and pale purple-white inside.

Why you'll love it

• Grape-coloured flowers. Blue-purple tubes open to a lilac-purple mouth, with a pale purple-white throat, an unusual colour combination.
• A proven garden plant. It has been grown in cottage gardens and stately home gardens for decades, which says a lot about its worth.
• Completely cold hardy. It shrugs off cold, so it suits gardens with properly frosty winters.
• A favourite of pollinators. The nectar-rich tubular flowers draw bees and other beneficial insects.
• Fast and easy. Given regular water, it grows quickly and rewards beginners.

Where it works best

Cottage borders. Plant 50cm apart in a sunny bed with roses, daisies and ornamental grasses. The deep purple flowers anchor a pastel scheme.

Wildlife gardens. A group of plants gives pollinators a reliable supply of nectar from summer to autumn.

Large pots. It grows well in a big pot, which brings colour and height to a patio or entry.

Growing Sour Grapes Penstemon in Australia

Position and climate. A sunny to partly shaded position suits it. It is frost tolerant and completely cold hardy, which makes it a good choice for warm temperate, cool temperate and Mediterranean gardens. In very cold areas, a sheltered spot or a wall helps it through the worst of winter. It keeps its leaves in mild climates and loses them over winter in colder ones.

Soil. Light, free-draining loam, sandy or chalky soil. Add grit and compost to heavy clay, so the roots never sit in wet ground.

Water and feed. Mulch and water regularly until established, usually around 12 weeks, and keep up regular watering since it grows fast. Fertilise after pruning with a slow release fertiliser, and add seaweed solution in summer heat.

Pruning. Deadhead after flowering to encourage a second flush. In mid-spring, cut it back to low-growing shoots, as the plant flowers on new growth.

What to expect when it arrives

Sour Grapes is sold as tube stock, a young plant in an 80mm deep tube that establishes quickly. It arrives small and leafy and bulks up through its first season. Tube stock comes from our grower and is not always available. The tube shows as sold out when the grower has none, and the notify button on the page emails you the day it is back.

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

• How to create a cottage garden in Australia
• Plants for cool climates
• Bee and butterfly friendly plants
• More flowering plants

Common questions

What colour are the flowers?

Blue-purple along the tube, changing to lilac-purple at the mouth, with pale purple-white inside. The effect is deep and rich, rather than a single flat colour.

Is it hardy in cold climates?

Yes. It is completely cold hardy. In very cold regions, grow it in a sheltered spot or against a wall.

Do I need to cut it back?

Yes. Deadhead after flowering and cut it back to low-growing shoots in mid-spring. It flowers on new growth, so this pruning keeps it flowering well.