Pale yellow-eyed grass
Pale yellow-eyed grass (Sisyrinchium striatum) growing here in a dry border with black onion, vervain, sage and mugwort. Its tall flowering spikes emerge in May and flower throughout June and July.
Starting with the largest member of the family, Sisyrinchium striatum is one of the most garden-worthy varieties. Its size suits it to the herbaceous border where it works well alongside perennials, bulbs and shrubs. When happy, a single plant can grow into a large clump of sword-like, grey-green foliage up to 40 cm (16 in) high and 60 cm (2 ft) wide. In summer the flower spikes rise to 60-80 cm (24-32 in) producing a fine display of yellow flowers in May and June. Unfortunately, it’s a rather short-lived perennial, typically lasting four to five years, so be prepared to replant it every now and then.
To do its best it needs full sun without too much shading from adjacent plants. This makes it suitable for a front of border accent plant or as an isolated specimen in a large pot or in gravel. It will, however, cope with being in the middle of a mixed border but performs best if given a bit of space. The flower spikes can look especially impressive when planted en-mass rising as a series of stiff zigzagging spires.
A clump of pale yellow-eyed grass is composed of many closely packed fans of broad flat grey-green leaves strongly reminiscent of those of the bearded iris. Each of these fans produces a flowering spike. You can get a sense of this in the photo below where we are looking at a series of such fans edge-on.
Looks good with:
A healthy clump of S. striatum can be positively striking, having a distinctly architectural outline which suits both modern and traditional gardens. It looks splendid isolated against hard landscaping: stone, rocks, gravel, walls or paving, or in contrast to small or round-leaved plants.
The flower spikes of pale yellow-eyed grass have an interesting zigzag silhouette which is emphasised when they are planted in groups, as shown in the photos below. Here, I have grown them in a narrow, sunny, box-edged border along the front of my house.
The pale-yellow flowers and bluish-green foliage is easy to accommodate alongside other plants. They complement blue and purple flowers particularly nicely, as well as grey-green foliage such as that of lavender or rosemary. Generally speaking, It has a comfortable affinity with drought tolerant, sun-loving plants including herbs and Mediterranean shrubs, however, it often does better with more consistent moisture, especially in spring.
These characteristics make it ideal for a range of planting styles, including Mediterranean, xeriscape, gravel and alpine gardens, foundation or pocket planting in hard-landscaping, but I have also grown it successfully for a couple of seasons in pots.
At the end of flowering, S. striatum usually produces plenty of seeds, which can be collected and sown in spring. Alternatively, plants can be divided in spring or autumn, and the divisions planted out or potted up. However, Sisyrinchium resents root disturbance, so divisions may take a couple of years to recover.
(1) Sisyrinchium striatum can self-seed excessively, although I have not had this problem this in my gardens. (2) After flowering, old leaves turn black and look unsightly. They are best removed. (3) Stems towards the outer edge of a clump can topple, especially in a windy spot. Provide support or cut them off.