Penstemon 'Razzle Dazzle'

Penstemons - Grow Guide

Find out all you need to know about growing penstemons in our detailed grow guide.

Penstemons are valuable garden plants for their long-flowering qualities. They're also popular with bees.

Penstemons vary, with some being suited to the alpine garden while the majority are at home in the heart of a herbaceous border. Border penstemons are praised for their tubular late summer flowers in an array of dramatic colour. The flowers look very similar to those of a foxglove.

While often described as hardy perennials, in a wet and cold winter plants can be lost. To offer them protection plants are not cut back until spring.

Discover how to grow penstemons in our comprehensive guide, below.

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Planting position

Border penstemons are perfect for the middle of a mixed border. They enjoy a fertile, reasonably moist soil that is free-draining. Full sun or light shade is ideal.

Planting technique

Plant in spring so that new plants get a foothold before having to face the winter. Stems are strong so it's only in very exposed garden that plant supports will be required. 

Propagation

Cuttings can be taken in late summer or early autumn. Select soft growth without a flower. Cut each cutting back to below a leaf joint and remove the lower leaves. More than one cutting can be put into a pot of cutting compost as long as the leaves don’t touch.

Place them in a sheltered spot in the garden or a cold frame. All being well they'll be ready to plant out the following May    

Troubleshooting

Penstemons are fairly short-lived plants. Take cuttings of your favourite penstemons every few years to ensure you have the next generation in place.

To prevent plants from failing to make it through winter, don’t cut faded stems back hard until spring.

If you continue to fail with penstemons ensure that the soil is not waterlogged. Dig in horticultural grit to improve drainage.


Care

In spring apply a general purpose fertiliser to your mixed borders. Water freshly planted penstemons for the first summer to help them establish on a dry soil.

In autumn cut back the faded foliage by just a third to prevent windrock and then cut the remaining foliage back hard in spring after the last frost.


Fork and trowel

Penstemons for quick colour

If you’re looking at your border in late summer and need to add some instant colour, penstemons are the answer. Plant in groups of three or five for impact. Most border types will continue to flower up until the first frosts. 

Penstemon 'Sour Grapes'
Penstemon 'Sour Grapes'

Penstemons to grow

  • Penstemon ‘Raven’ – dark maroon flowers from June to October. Reaches a height of 1m
  • Penstemon ‘Osprey’ – pink and white flowers from June to October. Height of 90cm
  • Penstemon linarioides subsp. sileri – bright yellow flowers on a lower growing plant of only 45cm. A half-hardy type for the front of a border with flowers in July and August. Not widely available

Related content

Best penstemons to grow

How to perk up your borders with tender plants

How to improve the colour combinations in your borders

Five bulbs to plant in February

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