Crown of thorns propagation

Euphorbia milii, commonly known as Crown of Thorns, is a species of Euphorbia known for its spiny stems and colorful, cup-shaped flowers. It propagates in several different ways, but cuttings provide the simplest and most fool-proof method of creating new plants at home.

When To Propagate

Crown of Thorns cuttings require warm conditions and bright light to root, so spring or summer are the best times to take root cuttings. Cuttings taken in autumn or winter will not have sufficient time to root before cold weather sets in and are more likely to produce an unhealthy, short-lived plant.

Choose a Cutting

Succulent new stems root more easily than older stems, so it is best to propagate Crown of Thorns in spring and summer when new growth forms. When choosing a cutting, look for a stem that is 2 to 4 inches (5 to 10 cm) long and no thicker than your pinky finger. It should have a few leaf buds or young leaves at the tip and no signs of damage or disease.

Photo via pinterest.com

Preparation

Between its sharp spines and mildly toxic sap, Crown of Thorns puts up a fight when it comes to taking cuttings. The right preparation helps minimize the risk of injury to yourself and to the plant. Be sure to wear thick gloves to protect your fingers from the plant’s spines and sap. Also, sharpen the blade of your cutting knife and clean it with rubbing alcohol to ensure a clean cut.

Take The Cutting

Crown of Thorns cuttings need to dry out before potting to reduce the risk of rot. Take the cutting by slicing straight through the stem 2 to 4 inches (5 to 10 cm) back from the tip. Rinse the cutting under cold water, then immediately dab the cut-end with powdered rooting hormone to stop the flow of sap. Set the cutting on a paper towel in a warm, dry place for a few days, or until the cut-end appears dry and slightly puckered.

Pot The Cutting

As with all succulents, Crown of Thorns need fast-draining, slightly sandy soil. Pot the cutting in a moist mixture of half potting soil and half sand. Stick the cut-end straight down into the center of the soil mixture, burying the bottom half of the cutting. Contact between the soil and the cutting is key to successful rooting, so firmly press the soil in around the cutting, taking care not to prick your fingers on the spines.

Cutting Care

Crown of Thorns cuttings require very little attention once potted. Simply set the potted cutting in a warm, dry place where temperatures stay above 70°F (21°) and protect it from direct sunlight. Use a propagation mat to warm the pot if your home is on the cool side. Drizzle water around the base of the cutting whenever the soil feels completely dry in the top inch (2.5 cm), but take care not to saturate the soil. New growth should appear in a few weeks.

Rooting in Water

Another method for propagating Crown of Thorns is to root the cutting in water. Simply take the cutting and place it in a tall, narrow glass with 1 inch (2.5 cm) of water in the bottom. Keep the cutting in bright, indirect sunlight and roots will appear in 2 weeks or less. Once roots appear, pot the cutting in a soil mixture specifically designed for cacti and succulents.

Warning

Crown of Thorns contain a white sap that causes irritation and burning on the skin and mucus membranes. Keep them away from children and pets.

Source: sfgate.com

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An ornamental planting of crown of thorns along a wall near Antananarivo, Madagascar

Euphorbia is a large genus of smooth and spiny shrubs and cactus-like succulents from 4” to 20 feet in the spurge family (Euphorbiaceae). Of the more than 1,600 species (including poinsettia, castor bean and cassava), crown of thorns, E.milii is a smallish tropical species from Madagascar that has long been grown as a houseplant or ornamental in warm climates. Many cultivars and hybrids have been developed that vary in flower size and color. The species name milii honors Baron Milius, once governor of the island of Bourbon, who introduced the species into cultivation in France in 1821. The common name refers to a legend that this plant was used as the thorny crown worn by Jesus at his crucifixion. There is evidence that this plant had been brought to the Middle East before the time of Christ, and the stems are flexible enough to weave into a circle, but it is more likely that another plant was used as his crown.

Euphorbia milii in the wild (L) and habitat (R), near Fort Dauphin, Madagascar

The species E. milli grows as a shrubby plant on a woody stem up to 3 feet tall. The variety splendens grows larger, 5-6’, and the hybrids are of various sizes. The greyish brown, branched stems, adapted for water storage, are 5-7 sided. The stem and branches are covered with prominent, 1″ sharp grey spines, although there are some clones that are nearly thornless. The new growth is sparsely covered with narrow succulent leaves. The smooth-edged leaves are 1½”long (some hybrids are much larger, up to 6″ long), obovate (wider near the tip) and are spirally arranged on the stem. The bright green to grayish green leaves naturally drop off as the stems mature, producing a scraggly appearance on older plants. The plant may completely defoliate when stressed (drought or high temperatures), but will later leaf out on new growth.

Typical Euphorbia-type inflorescences are produced throughout the year under ideal conditions. A specialized structure called a cyathium (fused bracts that form a cup) has a single female flower with 3 styles surrounded by five groups of male flowers, each with a single anther, and five nectar glands. Two of those 5 nectar glands have petal-like appendages that most people would consider the “flower”.

The buds (L), open infloresences (LC), inforescence closeup (RC) and closeup of cyathium (R)

On the species these are bright red, or yellow in E. milii var. tananarivae, which is often sold as E. millii var. lutea, but hybrids offer a variety of flower colors from white, cream and yellow, through many shades of pink and red. And some hybrids come in double forms. The flowers are generally produced in clusters (cymes) along the stem (axillary), but some selections bloom in terminal clusters. Sometimes poor flowering is due to too much light at night – these plants need darkness to initiate flowering.

Hybrid cultivars come in a variety of flower colors

Crown of thorns is available in a variety of sizes and colors

Crown of thorns is a quite tough plant in cultivation, taking extreme conditions and still looking good. Several species and cultivars in the E. milii complex were introduced into cultivation in the 1970s that were used in breeding to produce a wide range of plant forms and flower colors. Hybrids of E. milii and E. lophogona (which has long, leathery leaves) produced free-flowering plants with large, thick, deep green leaves. The California hybrids, developed for their stout stems and larger colorful flower bracts, are often referred to as “giant crown-of-thorns” series (e.g. ‘Rosalie’, ‘Vulcanus’, and ‘Saturnus’). German growers made selections of natural crosses in the wild similar to the California hybrids, but with thicker leaves and thinner stems, including varieties such as ‘Somona’ and ‘Gabriella’. The flowers, ranging in color from cream to various shades of pink and red, are often formed within other flowers. Many of these hybrids are patented, and many are marketed in very small pots, as they are tolerant of both drought and over-watering and bloom well in tiny containers. Short and Sweet™ is a compact dwarf cultivar with soft spines that is covered with small bright red bracts. ‘Mini-Bell’ is another dwarf cultivar with a compact growth habit and lots of small red flowers.

Euphorbia milii Thai ‘Yellow Crown of Thorns’

In the early 1990’s new, large flowered hybrids were produced in Thailand. These Thai Poysean hybrids were likely the result of a mutation, rather than selective breeding (Poysean is the name Chinese immigrants used for E. milii). The economic boom conditions of the time and demand for more exotic types of E. milii fueled the development of hundreds of cultivars, with a huge range of flower colors and plant sizes. Instead of just bright red or yellow, there were also many pastel shades, often with blends of different colors. And with cymes with more flowers, some looked more like hydrangeas than the typical crown of thorns. The form of these plants tends to be more upright and compact than the typical straggly-stemmed species, and the leaves are much larger and a brighter green. When the Southeast Asian economy crashed in the late 90’s, most of these cultivars were lost. Now there are only a few major growers near Bangkok that export these plants. The Thai hybrids are popular as collector plants but have not been successfully introduced in Europe or the US as mainstream flowering houseplants. There are many different cultivars available from specialty nurseries. A few include ‘Jingle Bells’ with soft pink bracts tinged with red and green; ‘New Year’ has buttery yellow bracts that change to cherry red as they age; ‘Pink Christmas’ sports cream bracts that develop pale pink and reddish streaks; and ‘Spring Song’ with creamy yellow bracts.

Bright red flowers adorn a crown of thorns

These plants can be moved outdoors for the summer. To prevent sunburn, acclimate them gradually to the higher light levels outdoors. The plants will benefit from rain water, but be sure to remove any dead leaves or matted flowers during periods of prolonged wetness, so that fungal diseases will not develop. Any plant part that turns brown should be cut off immediately so prevent the rot from spreading further.

Crown of thorns is grown as an in-ground plant in mild climates

Crown of thorns is quite tolerant of a range of conditions. This species prefers full, direct sun and average temperatures, but will grow in part shade (although flowering may be reduced). Some hybrids are better adapted to part shade. It will survive temperatures down to about 35F, so plants that are moved outdoors for the summer in the Midwest need to be moved indoors well before frost. It does well in low humidity, so succeeds in heated homes in northern climates. The species and varieties do best when the soil is allowed to dry between deep waterings. Many of the hybrids, however, do better with growing conditions more suitable for tropical foliage plants than typical succulents, and require more frequent watering. Fertilize lightly in spring and summer with a balanced fertilizer. Over fertilization will produce soft and vigorous vegetative growth and few flowers. E. milli is sensitive to boron, so be cautious about using fertilizers with high levels of micronutrients.

Many cultivars of crown of thorns can be kept in small pots

Most types of crown of thorns can be kept in small containers to keep the plants more compact, and will bloom even with restricted root room, but some of the hybrids need larger containers. Repot only when the plant outgrows its container, and replant using a rich, well drained planting medium, such as a commercial cactus mix amended with additional perlite, pumice, sharp sand or gravel and a little extra composted manure or other organic nutrient source. The plant can be set lower in the ground than its original level, particularly if the plant becomes too tall for the container (or to hide the graft union on some of the grafted hybrids). Replant in spring or summer when the plant is growing vigorously.

Crown of thorns is aptly named for the large spines on the branches and stems

Plants can be pruned to keep their shape and size. The milky sap will stick to and gum up cutting implements, so it is best to use a knife that is more easily cleaned, rather than shears. As with other Euphorbias, the copious, sticky, milky sap can cause dermatitis in susceptible individuals and temporary blindness if enough gets in the eyes, and is poisonous if ingested, so use caution when trimming or propagating this plant. Also beware of the sharp thorns! Cut the stems back to axillary buds to increase branching and a more compact habit, or remove entire branches back to their base to open the plant up. Remove weak or thin branches first to improve the vigor of the plant. Hybrids tend to need less pruning than the species, as they have been bred to be more branched and compact.

Crown of thorns is easy to propagate and has few pests

This plant is easily propagated from prunings or stem cuttings. Remove 3-6″ terminal sections and dip the cut end in cold water or powdered horticultural charcoal to prevent the milky sap from running excessively. Allow the cuttings to dry for 2-3 days before placing in well-drained planting mix (such as sharp sand, perlite and peat) to root. Keep the medium just barely moist – if too dry the cuttings will not root, but if too wet they may rot. They should root in 5-8 weeks when temperatures are warm. Potted crown of thorns often become run-down looking after many years; these plants are best discarded after establishing cuttings to replace the original plant. Plants can also be propagated by V cleft grafting using a 2-3″ stem tip on a 2-3″ stump, with ¾” matching wedges. Plants can also be grown from seed, but plants rarely produce seed without hand pollination with different plants.

Crown of thorns has few serious pests. Mealybugs are the most common insect pest in the Midwest, but spider mites, scales and thrips may occur. Diseases generally are the result of too much water, either in the soil or on the foliage.

– Susan Mahr, University of Wisconsin – Madison


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Some knowledge about growing from seed is necessary to germinate even the easiest seeds. Most seeds require humidity to germinate, even desert plants like Welwitschia mirabilis require that their growing medium remains moist until germination.

Most seeds require oxygen to germinate, if buried too deep in their growing medium, or if the medium is too wet, the seeds may not get the oxygen they require.
Some seeds need to be in the light (surface sown) or in the dark (sown deep enough to receive little or no light) to germinate. A rule of thumb is to cover the seeds their own width deep in the growing medium, but some seeds prefer to be sown much deeper, and some fairly large seeds like to be surface sown (or higher).
Many seeds germinate best at certain temperatures, some will germinate at a comparatively wide range of temperatures, yet others need fluctuating temperatures.
Almost all seeds are waiting in a dormant state for some outside stimulus to break their dormancy, some just need sufficiently high ambiant humidity, others need scarification, vernalization or to be passed through the intestines of an animal.

Euphorbia milii seeds will usually germinate in 10-15 days, even under good conditions germination may be erratic.
Sow Euphorbia milii seeds about 6mm deep in a Well drained seed sowing mix at about 25°C.

Pre chill HP for 7 day. Sow in lime-free compost.

The thorny Christ plant (Euphorbia milii) is a very popular indoor plant. This is due to its frugality on the one hand and its pretty little pseudo-blossoms on the other hand, which are no real flowers in the proper meaning of the word, but spathaceous bracts located on the shoot tips. They tirelessly appear almost all the year. In the case of indoor cultivation, it can grow to lush small bushes.

Plant Profile

  • Family: Euphorbiaceae
  • Botanical name: Euphorbia milii
  • Origin: Madagascar
  • Growth: succulent, leafy, with thorns, upright shrub-like, highly branched
  • Height as indoor plant: 10 – 50 cm
  • Leaves: small, green, oval, alternately arranged, depending on the species either evergreen or deciduous
  • Flowers: usually red, pink, rarely white or yellow
  • Use: Indoor plant, ornamental foliage plant
  • Poison: very poisonous, contains skin-irritating latex, poisonous to animals

The Christ plant which originates from Madagascar, belongs to the euphorbias. It grows as a succulent, leafy and thorny shrub, reaching a height between 10 – 50 cm, depending on the age. The name Christ plant is due to the resemblance between its branches and Christ’s crown of thorns.

Its shoots, all surrounded by spiky thorns are brownish and covered with small, oval leaves. The bright red, pink, white or yellow flowers grow on the shoot tips. Aside from the pure forms, there are many hybrids available.

Euphorbia milii with red flower color

Like all euphorbias, the Christ plant is poisonous. It contains poisonous latex which can cause irritation of the human skin and mucous membranes. Particularly endangered are toddlers and pets such as dogs, cats, bunnies, hamsters and guinea pigs which should not come into contact with this plant.

Care

Euphorbia milii is a very unpretentious and easy-care plant which will forgive one or two mistakes in cultivation. That makes it a perfect plant for beginners. Many lovers prefer the hybrids rather than the pure-bred species. In the case hybrids, the cultivators mainly focus on a great bloom density and a flowering period as long as possible. Regarding plant care, pure and hybrid varieties differ only very little.

Location

The Christ plant is a true sun-worshipper. The more intense and constant the sun exposure, the more intense the flowering and the longer the flowering period. Even the bright midday sun can not harm this decorative plant. In semi-shaded locations, the growth of blossoms is significantly reduced.

Warm rooms with normal room temperature and low humidity are perfect. The air should be dry rather than too humid and the temperatures should not drop below 15 degrees Celsius. Otherwise, the Christ plant would throw off its leaves. A spot on a south-facing window is particularly suitable, even though hybrids are more independent of daylight. From June to September, it can also remain in a rain-sheltered place outside.

Soil

Euphorbia milii prefers a permeable, humous and sandy substrate. This can either be a mixture of soil and sand or a substrate mixture composed of 1 part of humous soil or peat substrate, 1 part of loamy soil, 1.5 parts of quartz sand and 1.5 parts of lava granules, gravel or expanded clay. The ideal pH of the soil should be between 6 and 6.8. To protect the plant against germs, it is advisable to sterilize the country soil. Commercial soil is unsuitable, since it does not meet the requirements of the Christ plant.

Euphorbia milii – a popular indoor plant

Planting

This plant should be repotted for the first time immediately after purchase. Commercially available plants are usually delivered in conventional peat or flowering soil, which is rather disadvantageous for the Christ plant. Therefore, it should be repotted in a suitable substrate as soon as possible.

After this, young plants should be repotted annually due to their fast growth. For older specimens, repotting is recommended only every 3-4 years or as soon as the old pot has become too small and is no longer stable.

  • the best time is in spring
  • the new pot should only be slightly larger than the old one
  • if it is too big, the plant will focus on forming new roots
  • it will give less attention to growing flowers
  • besides that, there should be enough drainage holes to ensure the outlet of water
  • for the bottom layer in the pot, attach a drainage of coarse gravel or granules
  • add a some substrate mixture on the drainage and place the Christ plant on top
  • now fill the pot with substrate up to a few centimeters below the top edge
  • set the pot up carefully several times
  • this way, gaps in the root area can get filled
  • remaining cavities may threaten the stability of the plant
  • finally, press the soil down firmly and water; if possible use rain water

To protect yourself from the pointy thorns when repotting, the plant can be taken out and repotted for example using leather gloves, Styrofoam or cacti tongs.

Planting in hydroponics

The Christ plant is very suitable for both soil-bound and hydroculture, but converting it from soil to hydroponics is not recommended. It would be better, to raise this plant in hydroculture from the very beginning, meaning as a scion. Since the water demand of Euphorbia milii is rather low, it is advisable to use a water level indicator which should remain showing the minimum for this plant.

A water level indicator displays, when the plant needs to be poured. Depending on the season, this will be the case about every 3-7 days. As with the soil-bound plants, room-temperature and lime-poor water should be used for pouring. If there is no rain water available, you can also use stale tap water. It should be left to stand for at least one day.

Euphorbia milii with white flowers

Watering

The Christ plant’s water demand is low to medium. Thus, occasional pouring is perfectly enough. Pouring is to be done in a way that the root ball gets completely moistened. Let the top substrate layer dry before pouring again. If temperatures drop below 16 degrees Celsius, let the ball dry out to about half until watering again.

Despite this, however, the root ball should never completely dry out. Otherwise, the plant would quickly lose its leaves. On the other hand, excess water must always be removed from the saucer. In the case of hydroponics, the water level indicator will tell you, when to pour again.

Fertilizing

In the year that the Christ plant (Euphorbia milii) is repotted, fertilizing is completely unnecessary. From the next year on, you can administer a liquid cactus fertilizer via the pouring water from April to September every 14 days. When fertilizing, it is important to never fertilize the dry substrate, because this would burn the roots. Over-fertilization should be avoided as well; it would lead to the formation of long, thin and weak shoots. In the case of hydroponics, the administration of a suitable long-term fertilizer every three months appears to be useful.

Trimming

As the age grows, Euphorbia milii can reach considerable proportions or turn bald in the lower part, which may justify a cut back now and then. The plant tolerates trimming well and can basically be cut all year round.

  • the best time for trimming is in early spring between March and April
  • the cuttings can be used to produce scions
  • if you want the plant to grow more bushy, shorten the middle drive directly at the neck
  • to rejuvenate the Christ plant, it can be shortened by about two-thirds
  • it will usually thrive again
  • only use sharp cutting tools
  • this prevents bruising
  • it is important to disinfect the cuts after every trim
  • for this purpose, you can dust them with charcoal powder for example
  • this is to prevent germs or viruses from penetrating through the cuts

Because of the poison of the Christ plants, you should always wear gloves and, if possible, protective goggles during cutting operations, to prevent the highly irritating latex from touching your skin or mucous membranes and causing irritation there. Furthermore, it is useful to cut the plant outside or at least in a well-ventilated room.

Overwintering

During the cold season from October to February, the Christ plant should be treated to a 4-6-week rest period at somewhat cooler temperatures around 15 degrees Celsius. You can do this by drying it up, so to speak. That means, that the amount of water is gradually reduced until you finally only pour to keep the root ball from completely drying out.

Temperatures around 15 degrees Celsius in winter are conducive to the formation of new flowers. If, on the other hand, you keep pouring as usual, the plants tend to etiolate. They would grow long, thin and weak shoots which do not produce flowers.

While dry heating air is a big problem for most plants especially in winter, the Euphorbia milii almost desires it, even all year round. For hydroponics, the water level should also be lower then. Fertilizing is not to be done in winter, neither for soil-bound nor for hydrocultures.

Euphorbia milii is toxic in its parts of plants

Propagation

Sowing

A propagation of the Euphorbia milii, Christ plant by sowing is more elaborate than using cuttings, but still possible. For this purpose, the seeds are spread on the cultivation substrate, only slightly covered with soil and then moistened. Subsequently, the propagator is covered with a transparent plastic film or a plastic hood depending on the vessel, to create optimal germination conditions.

The whole is then put in a warm and bright place, but protected from direct sun exposure. To avoid mold and putrefaction, the cover should be removed daily for a short time to vent the substrate. After about 3-4 weeks, the first seedlings appear in most cases. When they are about 10 cm in size, they can be separated and put in small pots for further cultivation.

Scions

The best time for cultivating scions is in spring, ideally after cutting back the plant. Thereunto, 8-10 long shoot tips are cut off and the leaves are removed, apart from the upper ones. After cutting, you will notice white latex running out of the cuts. This so called “bleeding” can be stopped by placing the scions in lukewarm water until latex stops leaking out.

  • then let the cuttings dry in the air for 1-2 days
  • plant them in small pots using a slightly damp mixture of peat and sand
  • place the whole in a warm and bright spot without direct sunlight
  • temperatures between 22 and 25 degrees Celsius are optimal
  • a location near a heater would be fine, since warm feet support the formation of roots
  • the substrate is to be kept slightly moist over the entire time
  • after about four weeks, the cuttings will have formed their first roots
  • the young plants can be transferred to small pots
  • they should be further cultivated in a brighter, probably also full sun place
  • to receive more bushy plants, pot several specimens together

Since the Christ plant (Euphorbia milii) tends to quickly appear unsightly if you cut off too many scions, there is a possibility to receive several new plants from one cutting. Particularly older plants, which have dormant buds almost full-length on their shoots which can thrive again, are suitable for this purpose. These scions are not inserted into the substrate as usual, but they are planted horizontally. This way, they will thrive from several buds and quite a few rooted scions or rather young plants are produced.

Euphorbia milii with pink flower color

Cultivation in hydroponics

If you want to keep Euphorbia milii in hydroponics, it makes sense to already grow the cuttings in hydroponics from the very beginning. To do this, the lower leaves are removed from the cutting and rooting is done in willow water. Willow water can easily be self-made by removing the leaves from this year’s shoots of a willow and dividing them into about 2 cm small pieces, that are drawn into water for 24 hours. Then the water is poured off and the cuttings are set in.

Alternatively, rooting can also take place in a vessel filled with granules, whereby the used vessel should, of course, not have drainage holes. As soon as enough roots have grown, you can repot them in commercially available hydrotubes. It is essential to use a water level indicator and always keep it at the minimum.

Diseases

Thanks to its high content in poison, most pests usually stay well clear of the Christ plant. It is also relatively robust towards diseases. Nevertheless, too much water can cause root rot. Affected plants often can not be rescued. As a precaution, attention should be paid to drier cultivation.

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