Perennials are generally a really easy group of plants to grow. There’s a huge variety of choice ranging from ground hugging to head-high clumps. There are perennials for sun or shade as well as all different soil types, ranging from wet to dry. They will fill flower borders with leaves and flowers from early spring right through to late autumn.
Their other great advantage is that, at this time of the year, a lot of them grow really quickly, giving much needed impact. This brings interest whilst waiting for the slower-growing plants to catch up. So, if you’re planning a new border or need a section of the garden to look good quickly, here’s a selection of different height plants to fill the border.
Thymus serpyllum (thyme) ‘Pink Chintz’
Thyme is a quick and easy evergreen perennial to grow in full sun and quickly covers an area of ground as well as being used as a culinary herb. There’s a choice of almost 200 different varieties. Trimming plants after flowering will result in fresh new leaves being produced as well as prolonging the life of the plants.
This is an excellent, mat-forming ground cover cultivar, ideal for planting in a rock garden or sunny border. It’s covered in pink flowers during the summer which attract many different types of pollinating insect. If you plant clumps in paving cracks, the leaves can be trodden on without harming the plant, often releasing an aromatic scent.
- Flowers in summer
- Hardy
- Grows to 10cm tall
- Well-drained soil
- Full sun
- Exposed or sheltered
Vinca minor f. alba (periwinkle) ‘Gertrude Jekyll’
If you’re looking for a tough low-maintenance evergreen perennial to for ground cover in a shaded area, periwinkle is a great choice. Small leaf Vinca minor is very versatile and can be planted in both shade and sun as well as in containers.
This small, glossy leaved cultivar produces elegant nectar and pollen rich white flowers in early summer. The blooms show up particularly well in a shaded part of the garden.
- Flowers in spring
- Fully hardy
- Grows to 10cm tall
- Moist but well-drained, poorly drained or well-drained soil
- Full sun, partial shade or full shade
- Exposed or sheltered
Geranium (hardy geranium) ‘Rozanne’
Hardy geraniums are commonly known as cranesbill, and not to be confused with tender summer flowering Pelargoniums which are also commonly called geraniums. They are a fantastic group of perennials for bulking up a border fast and most will grow in sun or part shade.
Winner of the RHS Chelsea Flower Show Plant of the Centenary Award, this extremely long flowering, fast growing and wide-spreading herbaceous perennial is smothered in lavender-blue flowers. The blooms have a white ‘eye’ for months during the summer and early autumn months. They are perfect for planting near roses and filling gaps in flower beds.
- Flowers in summer
- Fully hardy
- Grows to 60cm tall
- Moist but well-drained or well-drained soil
- Full sun or partial shade
- Exposed or sheltered
Erysimum (perennial wallflower) ‘Bowles Mauve’
One of the longest flowering and quick to grow perennials is the perennial wallflower. It flowers almost year-round, even in winter.
This highly popular, woody stemmed perennial produces mauve/lavender colour flowers much beloved of bees and butterflies. It forms an attractive bushy mound shape. Although it’s relatively short lived, it’s very easy to take cuttings from.
- Flowers for most of the year
- Hardy throughout most of the UK
- Grows to 45cm tall
- Well-drained soil
- Full sun
- Exposed or sheltered
Lupinus (lupin) ‘Terracotta’
Lupins are a great choice if you’re looking for a fast growing, impact perennial with a cottage garden feel. Their statuesque spikes of flowers are available in a range of bright colours. Their large, lush leaves emerge in April at just the right time to hide the fading leaves of daffodils. They may need protecting from slugs and snails early in the season; try wrapping copper tape around parts of the stems.
As the name implies, this cultivar produces deep red rust-coloured flowers for several weeks, with the added bonus of being lightly scented. Cut off the flower heads after flowering to encourage the plant to produce fresh flower spikes.
- Flowers in spring
- Hardy
- Grows to 1m tall
- Moist but well-drained soil
- Full sun or partial shade
- Exposed
Acanthus mollis (bear’s breeches) ‘Whitewater’
Bear’s breeches are handsome fast-growing perennials that do well in full sun or part shade. They’re very showy plants when in full flower and clump up well and make a striking addition to the border.
The leaves on this cultivar are deeply cut and highly patterned with cream and white markings. They have statuesque, upright white flower spikes, tinged pinkish purple. These fast-growing perennials also do well in a large pot if kept well-watered and fed.
- Flowers in summer
- Hardy
- Grows to 1.5m tall
- Well-drained soil
- Full sun or partial shade
- Exposed or sheltered
Cephalaria gigantea (giant scabious)
There are a range of tall, fast-growing perennials to add to the back of the flower border. The giant scabious is one such plant that’s happy growing in part shade or sun but flowers more prolifically in full sun.
This plant forms clumps of pinnately lobed leaves at its base and throws up delightfully light and airy tall flower stems. The stems have soft yellow flower heads during the summer months which make great cut flowers.
- Flowers in summer
- Fully hardy
- Grows to 2.5m tall
- Moist but well-drained soil
- Full sun or partial shade
- Exposed or sheltered
Crocosmia (montbretia) ‘Lucifer’
Crocosmia very quickly form thick clumps of tall, upright flower spikes and sword-like foliage and look particularly striking growing in large swathes throughout the border.
This variety produces intense fiery red flowers on arching stems. They look particularly fantastic in a tropical planting scheme, producing handsome looking seedheads which remain on the plant well into early winter.
- Flowers in summer
- Hardy
- Grows to 2.5m tall
- Moist but well-drained or well-drained soil
- Full sun or partial shade
- Exposed or sheltered
Euphorbia characias subs. wulfenii (Mediterranean spurge)
Some perennial Euphorbias grow very quickly into thick, tall clumps and, as a result, make great statement plants.
This Euphorbia is no exception and looks wonderful in a Mediterranean planting scheme. It will add a great deal of drama to the border with its bluish green leaves and dome shaped lime-yellow flowers in early summer. Cut flower stems to the ground as they fade, but be careful when touching the plant as it easily gives off a thick, white sap which can irritate the skin and eyes.
- Flowers in spring
- Hardy through most of the UK
- Grows to 1.5m tall
- Well drained soil
- Full sun
- Sheltered
Whether you’re filling in gaps, or starting from scratch and need instant impact, these top picks for fast growing perennials are a great place to start.
David Domoney is a Chartered Horticulturalist, Broadcaster, and Author. David has worked with a number of the UK’s leading garden retailers as a plant buyer and strategic consultant. With more than 30 years experience, in horticulture, David is as passionate about plants now as he was when he bought his first plant at a village fete.
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Hi, the plant on the photo under “thyme” is not thyme but something like Silene acaulis I’d say.