How to grow… Irises
Irises are stunning flowers that offer a huge range of colours, impact, form and often scent as well. This last aspect is often not mentioned when discussing or offering irises for sale, so it hit me somewhat by surprise when I caught the rich, sweet almost sweetie shop scent of these deep purple blooms.
Their foliage can be semi-evergreen and is often strikingly upright, sword shaped, giving form and contrast with other border plants even when not in flower.
There are several different types of iris, and each has quite different requirements in terms of sun and shade, planting depth, protection from rough weather etc, so it’s worth defining exactly which type of iris you’re looking at before buying and deciding where to place your irises.
As part of a new ‘How to grow…’ series of blog posts, we’ll try to cut through the hype and shed a little light on this much loved range of flowering garden plants.
Bearded Iris – Iris Germanica
These are the biggest boldest irises, with the widest range of colours, often blooming early in the season, from April to June. Their ruffs and falls can be strikingly different in colour from each other, and some have delicately veined and patterned throats.
Their leaves are semi-evergreen and upright sword-shaped silvery green, giving great structure amongst the border plants.
Each stem will probably have three or four buds on it so although each flower will last only a few days, a clump of Iris Germanica can bloom constantly for around a month.
The secret to growing these beauties (such as Iris germanica ‘Jane Philips’ pictured left), is not to plant them deeply. Their rhizomes (the knotty tuber like base of the plant similar to a piece of ginger root) need to sit on the surface of the soil, with the roots tucked just below the soil level. Rhizomes need to be baked in the summer sun, so angle them to face southwards and plant in a reliably sun-drenched spot or you won’t get many flowers.
Once each bloom has shrunk back and faded, remove to keep the rest looking tip top. And take a moment to drink in their incredible scent.
Every 2 or 3 years, if your bearded irises are multiplying, you can cut up the rhizomes to create new plants, keeping a leaf on each new plant, and discarding the middle of the root which is no longer full and fleshy.
Siberian Iris – Iris Sibirica
Less fussy than Bearded Iris, these have finer, more grass-like leaves, and can be grown in shadier spots than their bearded cousins.
Available in a smaller range of colours, these range from deep blue to paler shades into white, often with a yellow patterning at the throat of the falls, and don’t tend to have any noticeable scent.
Whilst bearded iris thrive in dry spots, their Siberian cousins enjoy a damper position, and are perfectly happy in clay soil. They don’t tend to need staking and provide a lovely flush of colour and upright form in the early summer garden.
Flag Iris – Iris Pseudacorus
This is a British native iris, which is often seen at the edges of ponds and waterways.
Typically yellow, you can find ornamental varieties in blue and purple as well as white.
If you have a natural pond in your garden, you can grow flag iris as a pond marginal. It can be grown in a water plant basket, on a shelf on the edge of the pond so just the base is submerged.
You’ll need to cut the plant back hard, every couple of years or so, as it is vigorous in growth and will grow right through the basket.
Early bulbous Iris – Iris reticulata
One of the first spring bulbs to flower, these tiny delicate blooms can really brighten up your garden from late winter into early spring. They have incredibly intense colour, and come in shades of deep blue, pale blue, magenta, orange, and yellow.
Iris reticulata can be easily swamped in a bed, and appreciate really sharp drainage, so are best grown in a pot on a garden shelf or table, so their grace can be appreciated closer to eye level.
Unsure which kind of iris you have or want to learn more about how to grow irises in your garden? Get in touch with Chiltern Garden Design.
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