RHS harlow carr

Best plant and Ornamental Grass Combinations

Grasses combine well with many perennials to stunning effect. In the image above, Stipa tenuissima, a grass with wispy flower heads, is combined with Allium sphaerocephalon, blue cornflowers, and the seed heads of Allium cristophii to make a fine late summer display.

If you are looking for inspiration to see displays of grasses in a garden setting, the RHS latest flagship garden in Manchester Bridgewater has fantastic planting arrangements using various grasses.

More about How and Where to Grow Ornamental grasses

Below are some easy to grow combinations of perennials and decorative grasses.

Stipa tenuissima, Allium and Achillea

Stipa tenuissima, Allium and Achillea

This is a great combination which is at its best in July and August. Planted alongside the S. tenuissima is the late flowering Allium sphaerocephalon and terracotta Achillea. 

For this combination to work, the choice of Allium is important because many Alliums are spring flowering in May, and for this combination it is essential to plant the late summer flowering Allium which is A. spaerocephalon, which will flower in July and August. Plant this combination in a sunny spot with well-drained soil and it should return reliably each year.

Verbena bonariensis, Sedum, Aster and Pennisetum alopecuroides

Verbena bonariensis, Sedum, Aster and Pennisetum alopecuroides

This combination needs a sheltered spot only because this variety of Pennisetum is not fully hardy, only H3, which is coastal gardens and milder areas. It combines here well with the reliable perennials Verbena, tall purple spires and pale mauve Aster with the dark Autumnal shades of Sedum. This is an easy to grow combination if you have a sheltered spot and was spotted growing in a walled area of garden in an Oxford college. A hardier substitute for the Pennisetum would be Stipa tennuissima or Deschampsia to create a fully hardy combination.

Crocosmia Lucifer with grasses

Crocosmia and grasses.

Crocosmia looks good with certain grasses as they reflect and share with chosen grasses the arching habit. The variety illustrated is C. Lucifer,  which is tall and looks good teamed up with tall grasses, such as Stipa gigantea, or perhaps Stipa ichu, as both have an arching habit.

The smaller yellow and orange varieties of Crocosmia also work well and grasses such as  Deschampsia cespitosa and  Molinia caerulea, purple moor grass, look good together. Both Crocosmia and the grasses are easy to grow, simply plant in a sunny spot although the taller Crocosmia may require staking.



Thalictrum aquilegiifolium and Phalaris arundinacea

Most grasses like a sunny spot, but this is a combination  for damp ground and partial shade. Thalictrum (common name meadow rue) is an easy to grow perennial.  Phalaris arundinacea, common name gardener's garter,  has leaves with a mauve tinge which tones in well with the Thalictrum. It is also easy to grow and both plants are fully hardy. It can be vigorous, which means it is only suitable for large spaces, but ideal ground cover where needed. 


Molinia en masse

An effective planting scheme can be to repeat plant the same grass, as illustrated in this image, creating a shimmering wall of Molinia. This was a planting scheme at the Hillier garden in Hampshire and it looked really effective, especially with the sun catching the grasses.

Repeat planting of a single plant can be eye-catching. Check out plants for shade to see shuttlecock ferns planting in large groups looking very effective.

Stipa tenuissima, Allium,  Nigella and Cosmos

Stipa tenuissima, Allium,  Nigella and Cosmos

This is a combination found one year at RHS Harlow Carr and it is stunning. The soft flow of the Stipa tenuissima, purple heads of Allium, blue Nigella also known as love-in-the-mist, and chocolate Cosmos. 

The Allium and Stipa are easy to grow in any sunny spot, Nigella an annual,  would need to be resown each year.  One drawback of this variety of Cosmos is it is not fully hardy H3, and the tubers need to be lifted over winter. 

Stipa tenuissima and verbena bonariensis

Stipa tenuissima and verbena bonariensis

Idea dry planting combination of Stipa tenuissima and verbena bonariensis, the bronze of the grasses tones with purples in this case Verbena.

Ideal for a low maintenance dry area note that different varieties of Verbena vary in height and some are annuals.

Stipa gigantic

Central is Stipa Gigantea, with calamintha sylvatica, agastache

Another bronze/purple combination, this time Stipa gigantea with light mauve calamintha and darker purple of Agastache which is much loved by bees. All are frost hardy and perennial.

Molinia grass with Burnet  and purple loosestrife

Molinia grass with Sanguisorba officinalis, Great Burnet and purple loosestrife

A great combination for a semi wild setting and all are easy to grow. The Burnett will attract bees, and the loosestrife both bees and butterflies.

Towering over the planting is shimmering Molinia grass to make a lovely summer combination.

last updated 28.01.2022