About 2,000 species belong to the genus spurge (Euphorbia), which, depending on the species, can be annual or biennial, shrub or woody. The genus in turn gives its name to the family of the spurge family (Euphorbiaceae). Since it is very large and consists of very different species, they are often divided into sections and subgenera according to their origin and use for the sake of simplicity. All Euphorbia species are common in the tropics and subtropics, but also in the temperate zones of Central Europe and Asia. Apart from the houseplants, almost all species in our latitudes are at least conditionally hardy. A further characteristic of many Euphorbia species is their succulent growth with thickened, water-storing leaves and stems. This enables them to colonize even inhospitable, dry and stony mountain regions and semi-deserts.
Appearance and growth
Optically, the different spurge milk species and varieties differ considerably. Some grow over 150 centimeters high and are impressive appearances in the bed, others remain small and dainty. Still others remind of cacti. What they all have in common, however, is a relatively long flowering period, often lasting several months, and a special flower shape. Actually, the term “flower” is not botanically correct at all, because the most striking thing about the Euphorbia species are their yellow, green, red or orange bracts and bracts, which surround the actual, rather inconspicuous inflorescence – the cyathias – and attract insects of all kinds. In addition to the flowers, the colour and shape of the foliage also varies from species to species. The color spectrum ranges from gray blue to green to reddish. The leaves can be greyish and winter-green as in the case of the spurge wolf’s milk (Euphorbia myrsinites), but also lance-shaped and dark green as in the case of the spurge wolf’s milk. In addition, some Euphorbia species are characterised by a particularly beautiful autumn colouring.
The latex, typical of all spurge species, is toxic, irritates the skin and can cause allergic reactions. Therefore, Euphorbia is popularly said to be “as dangerous as a wolf”. The juice can be especially dangerous for small children and pets. Gloves are therefore recommended when handling spurge and contact with the eyes must be avoided as it can lead to temporary blindness.
Location and soil
The light requirements of the individual spurge species are similar – all prefer a sunny, warm place. Some like the marsh spurge (Euphorbis palustris) like it rather wet, but most prefer a dry to moderately moist, permeable soil. The native evergreen almond spurge (Euphorbia amygdaloides) also thrives in a semi-shade location with fresh soil. It is best to inform yourself about the location requirements of the Euphorbia species of your choice right at the time of purchase. The basic rule is: the more the conditions in the garden are similar to those in the natural environment, the better the spurge thrives.
For more sensitive species, such as the imposing Mediterranean spurge (Euphorbia characias ssp. wulfenii), spring planting is recommended so that they are well rooted until the first winter. One- or two-year-old perennials as well as shrubs are also planted after the ice saints in spring. The same applies to spurge species cultivated in tubs, for example the rod spurge (Euphorbia virgata). Depending on the species and variety, a planting distance of between 20 and 50 centimeters must be observed.
The cut varies from species to species. The leaves of deciduous Euphorbia species such as the steppe spurge (Euphorbia seguieriana ssp. niciciana) should remain over the winter as it is an additional winter protection for the plant. Winter and evergreen species do not need pruning and towards the end of winter you can share the species of spurge. This is sometimes quite difficult because of the partly somewhat woody roots. The division is often only possible with a sharp knife. Whether dividing or pruning, no matter what type of care work is performed on Euphorbia, be sure to wear gloves to prevent skin irritation. In this way you also protect yourself from spined specimens such as the Christ thorn (Euphorbia milii).
Wintering or winter protection
Before the first frost you should cover sensitive Euphorbia species planted in the bed with leaves or fir twigs. Wintergreen spurge species need winter protection during frost, especially during clear frost, and should not be exposed to direct winter sunlight. Species such as the poinsettia (Euphorbia pulcherrima) or the Christ’s thorn can go outside at temperatures above 15 degrees Celsius as soon as it gets colder, but they have to return to the house.
Since the spurge species can cope in nature at the most diverse locations, you will also find the right species for every garden situation. In the sunny gravel bed, prairie garden or rock garden with permeable soil, for example, the Walzen-Wolfsmilch feels very comfortable. The local cypress spurge (Euphorbia cyparissias) and the steppe spurge also thrive in dry locations. In the shrub bed, the yellow-green flower of the steppe spurge forms a pretty contrast to violet flowering species such as blue rhombus (Perovskia atriplicifolia) or catnip (Nepeta racemosa). Lower species are also well suited as groundcovers. These include Balkan spurge (Euphorbia amygdaloides ssp. robbiae) and purple cypress spurge (Euphorbia cyparissias ‘Fens Ruby’). Tropical species such as the poinsettia feel most at home in a warm and humid, bright place in the conservatory. However, they are usually disposed of after Christmas, as they can only be made to flower again with a little effort as short day plants.
As I said, there is a suitable spurge plant for every purpose and every garden. Some Euphorbia species are also well-known houseplants, such as the poinsettia, originally from Mexico, or the Christ’s thorn, while others are popular perennials, such as the roller spurge or the fire spurge (Euphorbia griffithii ‘Fireglow’). Winter hardy and perennial – and therefore very interesting for the garden – is, for example, the multicoloured or golden spurge (Euphorbia polychroma). Species such as Euphorbia acanthothamnos grow into regular shrubs and are cultivated and used like woody plants. Almond spurge is recommended as an evergreen ground cover. Palisade spurge (Euphorbia characias) with its varieties has a unique appearance. The easy-care and very persistent shrub grows into a shrubby hemisphere and impresses with its bluish leaves or strikingly hairy leaves. The variety ‘Emmer Green’ is also decoratively variegated. The honey-giving spurge (Euphorbia mellifera) is actually one of the shrubs, but is treated like a perennial in the garden. It smells pleasantly of honey in spring – the sunnier the location, the more intense.
Spurge is increased by sowing (usually self sowing) or division. Varieties are also propagated in spring by head or shoot cuttings, otherwise the offspring are not pure. The cuttings should be placed in a bucket or bowl of lukewarm water immediately after cutting so that the latex can run off. Otherwise it can happen that the dried juice hinders the rooting.
Diseases and pests
The species of spurge can be attacked by powdery mildew, thrips, rust or aphids. The poisonous latex protects the plants from many predators, but nudibranchs are not always deterred in some specimens.
In an interview with our store editor Dieke van Dieken, plant doctor René Wadas reveals his tips against aphids.Credits: Production: Folkert Siemens; Camera and Editing: Fabian Primsch
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