Mediterranean Garden Society

Unusual Bulbs for Mediterranean Gardens

by Johannes Ulrich Urban
photographs by Johannes Ulrich Urban

Photographs to illustrate the article published in The Mediterranean Garden No. 106, October 2021

The photo at the top of this page shows a flowering meadow with Gladiolus italicus near the Cabo de São Vicente. With some management (mowing after the seed is ripe) such a display can be achieved in a wild garden. (Photo Johannes Ulrich Urban)

Johannes Ulrich Urban gardens in Portugal on the very south-western tip of Europe.

He writes: There is a vast range of bulbs from mediterranean-type climates in different parts of the world which are very suitable for those who garden in exactly this kind of climate.  But many of these plants are barely known. They are adapted to the dry, hot summers and mild, wet or at least moist winters that are typical of this climate. Their natural places of origin are Chile, California, the Mediterranean Basin itself and especially South Africa, which in its winter rain areas is a hotspot of endemism and diversity. There is no other place on earth where the number of bulbous species is greater than in the winter rainfall areas of South Africa.

As waterwise gardening becomes more and more important, these bulbous plants are the perfect candidates for a garden with no or very little irrigation. Depending on the situation where they are planted and depending on whether they are grown in open soil or in a container, they may need the occasional watering in dry, sunny and windy spells in winter. During their active growth they do not like to go dry. This would not kill them, they are bulbs after all, but it might send them into a kind of premature emergency dormancy with maybe the loss of flowers and for sure less vigour in the following season. Other than that, they do not need water or even resent it once they are fully dormant during the hottest and driest time of the year; some would even be killed by water at the wrong time. Almost all of these bulbs have an internal calendar or clock combined with an internal thermometer. Once the time has come when the first rains can be expected, they wake up from their summer dormancy: some wait for the first rain to moisten the soil, others react to lower soil temperatures when autumn arrives while yet others simply start to flower regardless of weather, temperature and rain once they feel it is their turn.

So which are the unusual bulbs of the title? I have picked my personal favourites with no claim to cover all suitable ones.

Tropaeolum azureum

Tropaeolum from Chile: Dainty but surprisingly vigorous climbers with brightly-coloured flowers. They grow from small potato-like tubers, starting in early autumn with hair-thin, almost invisible shoots prone to damage. Once big enough to be visible, they need something to cling to. Best on a fence or trellis or climbing into a (deciduous) shrub. The most exquisite species is T. azureum with true blue open flowers. T. hookerianum has purplish-blue flowers, T. brachyceras is bright yellow and the easiest one is T. tricolor with tubular charming flowers in red, yellow and black. Yes, black. If grown in pots, they need a very small amount of water every four weeks in summer. One disadvantage with the exception of T. tricolor should not be concealed: they come from very dry climates in Chile and sometimes they skip one or even two seasons. The tubers remain perfectly healthy and will eventually sprout again but this is a challenge to the gardener’s patience… Very easy from seed, they flower in the first season from an early autumn sowing but seed is always scarce.

Cyclamen persicum: elegant and fragrant wild form beats its overbred offspring

Cyclamen, wild forms. Wonderful for naturalising in suitable places. Most are natives of the Eastern Mediterranean countries. There are principally two groups of cyclamen: autumn-flowering and spring-flowering. The former start to flower in late summer, often without leaves which appear later. These are Cyclamen hederifolium and C. graecum. For the specialist there are many forms and selections. Some C. hederifolium are scented. C. graecum likes full sun, while the other is a plant of dappled shade.

The main spring-flowering species is C. persicum, the ever so much more elegant parent of the over-bred florist’s cyclamen sold as a houseplant. Dainty slim white or pink flowers high above the foliage, scented. Most have a darker coloured “nose”. It likes full sun.

All cyclamens go completely dormant in summer. As their tubers grow rather shallow care must be taken not to damage them during dormancy. Once they are happy, and they are easy to please, they will self-seed. Their seed carries a sugary appendage which is loved by ants and other animals. who eat this appendage and discard the seed. This is how cyclamen seedlings can appear in the most unexpected places.

Lachenalia aloides var quadricolor: unusual colour combination

Lachenalia. This genus comprises an almost unknown group of plants, all from the winter rainfall areas of South Africa. The flowers of one group are reminiscent of aloe flowers while those of the other group are small urn-shaped and densely packed. They are often very bright with freakish colours or combinations. Two favourites are L. viridiflora and L. aloides var. quadricolor (syn. L. quadricolor) The first flowers in mid-winter in surreal jade green, enhanced by purple-brown spotted leaves, unbeatable in beauty in the rain. The second has tubular flowers that come in orange, green, yellow and aubergine, varying with the age of the individual flower. A good potful is quite a sight, again with the same purple spotting on the leaves. Easy from seed, many produce pea-like bulbils and are happy both in pots and in the open garden. But slugs also like the juicy leaves.

There are many more lachenalias in bright rose or red, pure yellow, purplish blue or white and many combinations of these colours. Some are strongly and pleasantly fragrant. All lachenalias are strict winter growers and dormant in summer. The dormant bulbs do not like to bake in very hot dry soil in the sun. I move the pots into a shady position for the summer. But flowering is best in full winter sun.

An oddity is L. mutabilis which changes colour, starting off a luminous blue then fading through yellow to greenish, always with black dots around the mouth of each small flower, aligned like pearls along the stalk. I have been discovering this underrated genus, guided by a wonderful book by Graham Duncan from the Kirstenbosch Botanical Garden in Cape Town*.

Ixia viridiflora

Talking about green flowers… Ixia viridiflora has another surreal colour. The tall slender inflorescences swing in the slightest breeze and carry a line of star-shaped iridescent green flowers with dark centres – their colour is difficult to describe and difficult to photograph. Surprisingly fast and easy from seed, this is a totally underrated plant, having flowered in the second season after sowing. It does well in pots that can be moved to a prominent position when the plant is in flower. The growing plant needs a constantly moist soil but once again, when dormant it needs to be dry.

Oxalis bowiei

Oxalis. Yes! Not all of them are weeds. There are true gems and the best ones are of course slow to increase. Here again are two groups: autumn and spring-flowering, the best flowering from autumn through to spring. The autumn-flowering ones are among the fastest plants to start after the onset of rain. Within days after the first drop falls bright flowers will appear, mostly before the leaves unfold but this will not take long either. There is an extreme variation in shape, size and growth habit, some Oxalis are not recognisable as such when not in bloom. The flowers all follow the same pattern but differ in size and number. Some are carried singly, others in umbels and some flower all along scrambling shoots. These flowers only open in direct sunlight. They are so bright that I wonder whether they might contain reflecting pigments. True blue is missing, but apart from that the whole spectrum is present, often in contrasting combinations and often so abundantly flowering that the leaves are barely visible. Some need a careful eye because they produce a lot of tiny bulbils and are potential weeds. I grow all of them in pots for safety reasons except for a few which have proved safe in the open garden. Oxalis bowiei is one of the best, with large silky pink flowers over a long time; it is easy, well behaved and not invasive.

Albuca spiralis with Oxalis massoniana

Albuca. This is a genus of bulbs with modest charm from different parts of the African continent. There are evergreen species, most are winter-growing and summer-dormant but there are also summer-growing and winter-dormant ones, all depending on where they are at home in a large distribution area. Each individual flower of an Albuca is somewhat similar to a snowdrop flower. Albuca flowers can be upright or downward-facing and they typically have a green stripe on the back of each petal, finer or broader. The size of the plants varies from ground-hugging dwarfs to 2m giants and everything in between. The flowers are borne on long racemes. One of the most spectacular species is A. clanwilliamigloria with bright golden downward-facing flowers (without green stripes) on a stalk up to 2m tall. In its native habitat it grows inside huge tussocks of Restio (rush-like South African endemics) which gives the long and slender inflorescence some stability. A. nelsonii is not quite as tall with upright white, scented flowers with a green stripe. It forms huge evergreen clumps and is a good waterwise plant for dappled shade. Another impressive giant is A. batteniana. Its flowers are greenish-white but it is the most impressive evergreen foliage that makes it a magnificent architectural accent plant. Not quite as big but still vigorous is the evergreen spring-flowering A. aurea with upright-facing yellow flowers with a broad green stripe. To break the rule of winter-growing bulbs there is the lovely A. tenuifolia (syn. A. shawii)with bright yellow hanging flowers and foliage that is delightfully liquorice-scented when rubbed. It is a beautiful subject for a pot, sheltered from winter rain, but also possible in the open garden with summer water.

Gladiolus priorii, first flowers from an autumn 2018 sowing

Gladiolus: Everyone knows the large hybrid garden gladioli; they are summer-growers and for many people they are just too showy. The wild species, however, have kept their natural elegance and charm. There is a huge number of species of which many are winter-growing and summer-dormant. However, most species gladioli are not ideal for the beginner. They take much longer from seed to flower than other bulbs and have their requirements – if these are not met the corms may disappear. Many are of small stature and have very fine grass-like leaves so they are best grown in pots in order not to be weeded accidentally. But there are native Gladiolus species in many Mediterranean countries which are lovely and easy, Gladiolus italicus and G. illyricus, difficult to distinguish. They can easily naturalise in flowering meadows if the grass is not too dominant (see photo at the top of this page).

This magnificent Babiana is happy among its succulent company

Babiana: This group of South African bulbs comes in very striking bright colours. They are easy to please in a place in full sun. Their flowers in satiny red, bright blue, sometimes yellow and often with other contrasting colours give quite a show, especially when grown in large numbers. Their name refers to the baboons which like to dig up and eat their bulbs. The plant has adapted to this by producing tiny bulblets which will be missed by the monkeys. The main bulb will have fed the animal but the bulbils maintain the species and are an excellent material for propagation.

Iris xiphium var lusitanica, a rare native bulb

Iris: This vast genus embraces many species which are eminently suitable for a mediterranean Garden. Botanically they are divided into several groups, mostly referring to their different storage organs: rhizomes, bulbs, bulbs attached to very fleshy succulent roots. Many are fragrant, some are difficult plants for the connoisseur only but most irises are rewarding and easy garden plants requiring no summer water. Good ones are Iris albicans, blue I. xiphium and the yellow variety I. xiphium var lusitanica, I. lutescens in different colour forms and many, many more. The Iris xiphium group is one of the parents of the so-called Dutch Iris which is also very suitable for mediterranean gardens and easily available.

Sparaxis: a group of South African corms with leaves like a small Gladiolus and very bright flowers. The best known is Sparaxis tricolor with orange, black and yellow flowers which is a vigorous and never disappointing plant. A more refined species is S. elegans of which the white form is of exquisite beauty: pure white flowers with an intricate central mark of black and purple with contrasting small yellow dots, all with a metallic sheen.

Tritonia: the plants look very similar to Sparaxis but the flowers are different. Each petal has a translucent “window” at its base. The flowers are not as bright as those of Sparaxis and come in orange or reddish tones. But a mass planting of Tritonia is quite a sight.

Both Sparaxis and Tritonia are easy to propagate either by cormlets or seed and are good candidates for naturalising in suitable places.

Watsonia marginata in full bloom in April, in front of blue Echium candicans.

Watsonia: Towards the end of spring and with some species flowering into summer, watsonias are the queens of the flowering bulbs. Some are evergreen and need summer water and some are winter-growing and the perfect plant for a waterwise garden. My personal favourite is Watsonia marginata. It has lush sword-shaped leaves well into late spring and flowers towards the end of spring with scapes of pink flowers more than 2m tall. These tall inflorescences withstand wind as if they were made of steel wire, looking like a giant bouquet leaning and swinging gracefully outwards. A magnificent accent plant. Later the foliage and steel wire stalks die down and need a trim. It needs some water after flowering until the leaves die down naturally. Then it is kept totally dry in the succulent and bulb border. The picture shows a 3 year old clump.

There is one species of watsonia everybody should avoid: W. meriana var. bulbilifera. The name bulbilifera says it all… this plant has decided to replace flowers with small bulbs which will eventually fall to the ground and start a new plant which does the same. They are aggressive weeds in many suitable climates. Another word of caution: I was told by a friend who is an experienced gardener that watsonias do best on lime-free soils and may fail on lime. As I garden on granitic lime-free soil, my experience is no point of reference for this question.

The last spring-flowering bulbs is the Californian Triteleia. It comes in blue, purplish blue or yellow. Its flowering takes place at the end of the growing season, with leaves already withering or even completely dry. These plants benefit from some water until flowering is over. This is a group of spring bulbs that is new to the author. They are best grown in large numbers and make quite an impact.

There are so many more. Exotic-looking Ferraria with green-brown-yellow and black flowers, bright crocus-like Romulea, the large group of Ornithogalum, delightful dwarf Narcissus, a whole collection could be started with alliums alone, the winter-growing Anemone and Ranunculus species and last but not least the huge array of Mediterranean orchids, all of them spending the summer dormant in their bulbs or tubers. Orchids should never be disturbed in nature but they should be present in any Mediterranean garden provided no such things as weed killers are in use. The more common bulbs like Amaryllis belladonna, Scilla peruviana and Freesia are no less attractive.

I would like to encourage garden owners to experiment with new bulbs. There may of course be the odd failure, as always in gardening. But an overall reward can be promised.

Further information on this huge group of fascinating and beautiful plants can be found in the WIKI of the Pacific Bulb Society. The Pacific Bulb Society is affiliated with the MGS and offers a seed and bulb exchange twice a year for members with an address in the EU where some of the bulbs mentioned or their seed may be offered. The next EU exchange will take place at the end of October 2021. Or a worldwide exchange through the US-based seed and bulb exchange, depending on the import restrictions in your country.

* The Genus Lachenalia by Graham Duncan, published by Royal Botanic Gardens, Kew, 2012

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