Crocosmias

I knew originally knew them as montbretias, those in the US will know them as copper tips or falling stars. Members of the iris family they hail from South Africa. When I was a boy most people had them somewhere in the garden along with golden rod (solidago) and Michaelmas daisies (asters). They were always in flower in seaside gardens and I remember seeing crocosmia naturalised on sea cliffs. They are grown worldwide and were probably originally introduced to other countries along sea routes.  Their wide distribution has led to Crocosmia x crocosmiflora becoming invasive in parts of the US, UK and New Zealand.

The Latin name comes from the Greek Krokos, which means saffron. Apparently the dried leaves smell of saffron when infused in boiling water. How obscure is that? Crocosmias grow from corms. Each year a new corm grows on top of the old one, just like gladiolus.  They do not get nearer the surface of the ground because the roots on the bottom corm are able to draw the corms deeper into the ground when growing conditions permit.

The sword shaped leaves give the plants a sharp, architectural quality and they are a good contrast to the softer form of many other perennials. The seedheads of some varieties are particularly attractive and are sought after by flower arrangers more than the blooms.

Crocosmias need an open sunny position to flower well. The corms do tend to become overcrowded after a few years and their performance declines as foliage is forced to grow up towards the light making it weak and liable to collapse. They can be grown from dry corms planted in late winter of early spring but more often they are purchased as growing plants ready to make an almost instant impact in the garden. Although more expensive, buying them this way at least you can see what you are getting.

Crocosmias are frequently used in “hot colour” planting scheme with vibrant dahlias, cannas, heleniums, rudbeckias and all of those perennials that glow in the late summer garden. They also work brilliantly with blues: ceratostigma, perovskia, lavender and the like. The sharp leaves and vibrant blooms also make a wonderful partnership with grasses. Tall ones with prairie grasses such as panicum and calamogrostis and short ones with the light and airy Stipa tenuissima. Tall still stemmed grasses lend support to varieties like ‘Lucifer’. The shorter varieties of miscanthus can also be good with the shorter crocosmias.

Of all the named varieties the tall and vigorous Crocosmia ‘Lucifer’ is the best known. This has slender fans of ribbed sword shaped leaves reaching 90cm, 3ft or more in height. The flower stems reach well above this. The blooms are relatively large and vibrant scarlet with a hint of glowing flame. ‘Lucifer’ is tall and needs to be planted further back in the border amongst tall, stout subjects which will lend support; alternatively install hazel twigs early in the season. ‘Lucifer’ looks stunning growing with the blue-grey foliage of Rosa glauca.

Unfortunately because ‘Lucifer’ is so well known and desirable many inferior forms are sold under that name. Actually I do not think it is the best choice for most gardens: it is tall and is liable to collapse without support.

On the other hand the lovely small-flowered Crocosmia ‘Carmin Brilliant’ will fit in anywhere. This is smaller in stature, 60cm, 2ft or so with finer more delicate foliage. The branched flower spikes carry many fire-fly blooms of carmine red. It flowers for a long time, has great seedheads and fits in to most gardens much more comfortably.

Another really well known crocosmia, ‘Emily McKenzie’ has much larger flowers than most. The blooms are more like sparaxis than the common montbretia. Each bloom is large and open, warm copper orange with mahogany bars on the petals. Again it is only 60cm, 2ft in height and is easy to fit into the garden. I’ve planted it against the shining mahogany bark of Prunus serrula; a combination I am really pleased with.

I would always choose the orange-red crocosmias over the yellow varieties. However in the right situation the yellow ones are light and bright and add a little sunshine to the planting.  I find ‘George Davidson’ one of the most useful. The flowers are small, the leaves fine and the flower stalk slender and elegant. It is a soft, deep yellow and subtle enough to sprinkle through a planting scheme to give it a late summer lift.

Crocosmia ‘Buttercup’ on the other hand is larger in bloom and earlier flowering. The blooms are a pleasing shade of yellow, not hard and are held beneath the flower stems. It is a good choice with dark green or yellow-variegated shrubs and is lovely with anything blue.

Despite their strong lively colours crocosmias are surprisingly good mixers that fit into a great variety of planting schemes from the traditional herbaceous border to prairies style planting. They also work brilliantly in tropical planting schemes with more exotic subjects. Some may have behaved badly in native environments, but they have certainly enjoyed enduring popularity in gardens across the world.