Care Guide

Iris Species and Varieties

By Rupert Foxton-Smythe

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Bulbous irises are among the most refined and enchanting plants of the early garden, yet they remain surprisingly underused. Compact, delicately scented, and rich in color, many species thrive equally well in borders, rockeries, grass, and indoor pots.

TL;DR

Bulbous irises are compact, fragrant, winter- and spring-flowering plants ideal for pots, rockeries, and borders. They require shallow planting, cool conditions, and well-drained soil, rewarding gardeners with early colour and perfume when little else is in bloom.

Many of the iris species must be considered amongst the loveliest subjects of the bulb garden, yet it is remarkable how little known are most of them. Most are suitable for pot culture in the home and it is surprising that more are not commercially grown for sale in pots when they would make a welcome change from the usual tulips and hyacinths. Particularly am I thinking of the lovely Iris reticulata which will come into bloom in January, reaching a height of only 8-9 in. This is the ‘netted’ iris, so called on account of the strange netted coating of the bulbs.

It will prove an outstanding plant for a rockery where its dainty foliage and habit does not give an appearance of coarseness in any way. The plants are at their best when planted near a rock, particularly if it is a piece of weathered Yorkshire stone, which is greyish white in color, and which shows off the rich purple, crimson and pale blue colors of the bloom to the greatest advantage. On the rockery or as an edging to a border it will come into bloom mid-February, at a height of only 6-7 in. Planted in short grass where it looks delightful, it will reach a height of 9-10 in.

In the semi-shade of trees, particularly amongst the silver birch, with their brightly colored winter bark, the bulbs may be left untouched for several years when they are best lifted, divided and replanted during September. The bulbs should be planted no more deeply than 1 in – they should be just covered with soil and no more. They love a cool moist soil, which is provided by incorporating some peat or leaf mold, or even some rotted manure into the soil, and they do appreciate a peat mulch early in summer to protect them from a hot sun.

But it is in pots that they look at their best. They should be planted six bulbs to a pot in early September, well watered and placed under a covering of ashes just as for other bulbs. There they remain until taken indoors early in November. They must be given only the coolest of temperatures, whether in the home or greenhouse, in no way will they stand forcing, for it must be remembered that they will bloom unprotected in the open before the end of February. The blooms carry a delicious perfume which will scent a large room, when the blooms are fully open. No lovelier plant will be waiting to greet the new year and being quite inexpensive at least one pot should be in every home.

After flowering the bulbs should be slowly dried off and then replanted outdoors as soon as their foliage has died away. The flower head should be removed as soon as they have passed their best.

Species

  • Iris reticulata. This is the native iris of the Caucasus, strongly perfumed – the color being rich purple-blue with attractive orange marks on the petals.
  • I. reticulata Can tab. A superb plant of recent introduction, bearing blooms of a pure Cambridge blue shade, striped orange on the fall petals. Though of a delicate color the blooms are well able to stand up to winter conditions but are at their best when planted in pots.
  • I. reticulata Hercules. A magnificent contrasting color, the blooms being almost bronze-colored with beautiful orange markings on the falls.
  • I. reticulata Krelagei. An old variety which carries almost no perfume, but it bears a bloom of a warm deep crimson color. A strong grower of refined habit and slightly earlier flowering than the others.
  • Iris alata. The first of all irises to bloom – from an early August planting it will come into bloom in a sheltered border in the open in early November. It likes a dry soil, one well enriched with lime rubble. Flowering at a height of only 8-9 ft. it is also a most suitable plant for a cool-house. It bears a rich lavender-colored bloom with the lower petals colored gold.
  • Iris Bakeriana. A member of the reticulata section and carrying the same rich fragrance. It is even earlier flowering, coming into bloom in a sheltered corner immediately after Christmas. The blooms are almost of a sea-green shade, blotched and marked with yellow and black blotches. Slightly taller growing than the reticulata, but equally valuable for indoor pot culture.
  • Iris Bucharica. This is a lovely species from Bokhara, where the best carpets are made. It bears, in early May, a spray of pale yellow and white blooms enhanced by the rich shiny bottle-green color of its foliage. It likes a dry, sunny position. The bulbs should be planted in October. It is a grand rockery plant but not very suitable for indoor pot culture.
  • Iris Danfordiae. Introduced to Britain in 1899, this is another winter-flowering iris. On a sunny February day it may be seen opening its orange, brown and yellow blooms amidst the melting snow. It also does well in pots given the same treatment as the reticulata.
  • Iris histroides. Coming into bloom in the open in early March, this is a delightful iris to follow on Danfordiae. The blooms are of brightest blue, crested with gold and it is perfectly hardy even in an exposed position. It is an excellent plant for indoor flowering in February.
  • Iris orchoides. A rare and expensive variety, but so beautiful that at least one or two should be planted in every garden. The primrose yellow blooms appear in April at a height of 15 in. and look particularly lovely when planted in short grass under trees.
  • Iris sindjarensis. A lovely iris which bears its fragrant violet-grey blooms during March. It is unusual in that its blooms are borne in clusters of three or four on stems 12 in. long. It requires a well-drained soil and a position where it can be kept as dry as possible such as under a wall or beneath a clump of conifers or cupressus trees. It will bloom well in pots in a cool-house. Outdoors it is best planted in October.
  • Iris sisyrinchium. An inexpensive and delightful plant bearing its small purple flowers during April, May and June. The blooms last only a day, but are constantly being replaced by others right through early summer.
  • Iris tingitana. A native of Tangier and not quite hardy though in the south-west it will bloom abundantly in the open. It should be given a dry position, one where the summer sun will bake the ground. Should the summer be wet and sunless the bulbs may tend to rot away. Indoors it is a splendid subject for planting in large pots or boxes. The rich deep blue flowers have a vivid orange spot on the falls.

English Iris

  • Mansfield. Of a rich wine purple shade.
  • Mont Blanc. Purest white and a strong grower.

Spanish Iris

  • Cajanus. This is a late-flowering variety of a rich golden yellow, valuable in bridging the gap between the Spanish and English flowering-times.
  • King of the Blues. A strong grower, producing its deep purple blooms during June.
  • La Reconnaissance. An unusual shade for bulbous irises, this variety bears blooms of attractive rich bronze with golden blotches.
  • Queen Wilhelmina. Bears a neat white flower which has a small yellow blotch on the fall petals.
“No flower greets the new year with greater elegance than the early iris, rising fragrant and jewel-bright from winter soil.”

More Information On Iris Species and Varieties

Many species of iris deserve far greater recognition for their beauty, fragrance, and adaptability. Among the finest is Iris reticulata, the netted iris, named for the distinctive mesh-like coating of its bulb. Flowering as early as January in pots and February outdoors, it produces richly coloured blooms in shades of purple, crimson, and blue, carried on neat stems just a few inches high. Its dainty habit makes it ideal for rockeries, edging borders, short grass, or planting beneath silver birch trees where winter bark enhances its colouring. Bulbous irises thrive in cool, moist but well-drained soil. Shallow planting is essential; bulbs should be covered by no more than an inch of soil. Incorporating peat, leaf mould, or well-rotted manure improves conditions, while a light summer mulch protects bulbs from excessive heat. Once established, clumps may remain undisturbed for several years before being lifted and divided in early autumn. Pot culture reveals these plants at their finest. Six bulbs planted to a pot in September, kept cool and well watered, and brought indoors in November will bloom naturally without forcing. Cool temperatures are essential, as these irises are naturally winter-flowering plants. Their blooms release a strong, delightful perfume capable of scenting an entire room, making them perfect for seasonal indoor display. After flowering, blooms should be removed promptly, and foliage allowed to die back naturally. Bulbs should then be dried gradually and replanted outdoors. Beyond Iris reticulata, many species offer beauty across late winter and spring, from the vivid yellows of Iris danfordiae to the pale primrose tones of Iris orchoides and the fragrant violet-grey clusters of Iris sindjarensis. Together, they provide a long succession of refined colour from winter’s edge into early summer.

About the author

Rupert Foxton-Smythe

Rupert Foxton-Smythe is a seasoned horticulturist and avid plant enthusiast with over three decades of experience in the field of botany. As a leading expert at Houseplant Guru, Rupert brings a wealth of knowledge and a deep passion for all things green.

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