crown-of-thorns

order: malpighiales
family: euphorbiaceae
genus: euphorbia
species: milii

First Story

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21 april 2012

Crown-of-thorns is a plant I knew as kid. Our neighbour used to have a bush in front of their house. It's a plant that had the same level of popularity as ixora at that time. I must admit that before this I'd never really liked it. After being to botanical gardens in the past year my interest for plants escalated tremendously. From that instant on I already knew that this plant was going to be in my wish list.

Again I got this plant as a discounted item for 0,90 eur. I think the reason the plants were in sales was because it was a low season in winter, where people don't usually go look for plants. But I did. If I had more room at home I'd probably got a dozen more plants.

This plant belongs to the spurge family. In German it's called 'Wolfmilchgewächse' which is literally translated as 'wolf milk plants'. So called probably because these plants contain white sap that can be poisonous if in contact. The genus 'euphorbia' is the most diverse genus in the family and is one of the most diverse in the entire plant kingdom. Like many other spurges, euphorbia milii also have colourful leaf-like bracts surrounding the inflorescence. Its structure is very similar to that of its close relative, poinsettia (euphorbia pulcherrima). Red bracts (other colours exist in both species), small inconspicuous inflorescence, thin green leaves that tend to change colour in response to light exposure. The differences between the two make it even more interesting. That makes one realise how manifold the nature actually is. As the name reveals, crown-of-thorns have got thorns all along its stem. The inflorescence tubes ascend vertically and branch out further at tips. They don't grow towards the light. They just want to grow higher to get attention from fellow pollinators.

It's quite easy to care for this plant. At least I haven't got any big issue with mine up until now. Just let the soil dry out between watering. Bright window sill. Keep above 13 °C to prevent leaves drop. Ideally more than 8 hours direct sunlight daily. Fertilise sparingly in summer as over-fertilising prevents blooming. Trim branches to shape plant in early spring. Spray cut end with cold water to stop bleeding. And be warned again that its sap is poisonous and is lethal to fish.

Update

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31 march 2015

september 2014.

This is the first update after 3 years of growing it. It has grown tremendously during these years and has been potted up 3 times, mainly for the reason that it doesn't topple over easily. The stems have elongated manifold, though there is no branching to be seen nor has there been any new stem. I decided, at least for now, not to prune them back and will just let it grow the way it grows naturally, which is pretty much vertically.

From my experience growing this plant, I can confirm its hustle-free maintenance for which reason it also lends itself to certain degree of neglect. Short periods of drought do it no harm. However I like to water it regularly when it's growing outside in the hot summer sun and frequently feed it with diluted balanced fertiliser, which clearly improves the colour of the leaves and the bracts.