Petty spurge (Euphorbia peplus) is an annual plant from Europe, Asia, and Africa. It is fast-growing and has become invasive in some countries because it outcompetes other species for resources such as moisture and sunlight. Petty spurge latex is mildly toxic, has nevertheless attracted the attention of researchers in the US and Germany who hope to isolate useful compounds from it.
I. Appearance and CharacteristicsÂ
Euphorbia peplus (petty spurge, radium weed, cancer weed, or milkweed), is a species of Euphorbia, native to most of Europe, northern Africa and western Asia, where it typically grows in cultivated arable land, gardens and other disturbed land.
Outside of its native range it is very widely naturalized and often invasive, including in Australia, New Zealand, North America and other countries in temperate and subtropical regions.
It is an annual plant growing to 5–30 cm (2–12 in) tall (most plants growing as weeds of cultivation tend towards the smaller end), with smooth hairless stems. The leaves are stalked, oval-acute, 1–3 cm (0.4–1.2 in) long, with an untoothed margin. It has green flowers in three-rayed umbels. The glands typically of Euphorbia are kidney-shaped, and have long thin horns.
var. minima has stems low, ascending, branchy, leaves roundish, seeds smaller 1-1.4 mm (vs. 1.3-1.6 mm of var. peplus), predominantly countries on the north edge of the Mediterranean (PoWo Map)
II. How to Grow and Care
Sunlight
Spurges naturally grow in places that have plenty of sunlight, but some species can tolerate partial shade (e. g., Euphorbia amygdaloides var. robbiae). Full sun provides the best environment for spurges. If they are grown indoors, spurges need at least 6-8 hours of direct sunlight every day for proper development.
Temperature
Genus Euphorbia is very large and diverse, so its different species can be found in various habitats, but the majority are well-adapted to a temperature range of -29 to 4 ℃. Many spurges, in spite of having succulent leaves, cannot handle long periods without moisture and need to be watered weekly during hot summer days. Some cactus-like species are well adapted to high temperatures and prolonged dry periods, but most species used for landscaping and decorative gardening require more moisture for proper development.
Watering
Petty spurge needs regular watering about once a week, especially during growing seasons. The plants don’t need great amounts of water during temperate environmental conditions, but during hot summer days they need as much water as any other plant. Petty spurge needs to be watered when the planting medium is dry for 5 cm at the surface. Those grown in indoor environments also need a sufficient amount of moisture during the resting season. To avoid excess moisture in the medium, it is best if small amounts of water are added from below.
Soil
Spurges aren’t picky when it comes to soil type. They can grow in a variety of soils. Some species of Euphorbia can even thrive in nutrient-poor soils, requiring only that the soil be well drained. If the soil is full of moisture and is prone to water retention, it will most likely cause root rot.
Fertilizing
Petty spurge doesn’t require large amounts of fertilizer for normal growth and development. In fact, very little fertilizer is required. As mentioned earlier, some species can thrive even in very poor soils, as long as those soils are well drained. Fertilizer should only be applied when the plants start showing nutrient deficiency symptoms on lower leaves. When the lower leaves turn yellow, it is time to add half-strength liquid fertilizer to the soil. That will keep the plant well fed for several months.
Planting Instructions
Dig a hole twice as wide as the plant’s root ball before planting. Then, turn the container with petty spurge upside down and let the plant slowly fall into your hands. Place the plant upright in the hole and slowly fill in around the roots with loose and fertile potting mixture, adjusting the planting depth until it is just right. Water it once. Do not overwater, as standing water is not good for the plant.
Pruning
In early spring, if there are any damaged stems, they need to be removed to keep the plants healthy and to optimize their nutrient management. It is advised to cut back a certain number of stems after blooming in order to stimulate consistent flowering and growth of new foliage. When cutting a stem, cut at the stem’s base. It is very important to use gloves while handling and pruning petty spurge, because their tissues contain milky-white latex sap which is poisonous and can irritate the skin.
Propagation
Petty spurge can be successfully grown from seeds, but the seeds are rarely commercially available because they are difficult to germinate and stay viable only for a short period of time. Petty spurge is most commonly propagated via cuttings.
It is important to wear gloves while working with petty spurge cuttings and to clean the pruning shears thoroughly after pruning, so that any unwanted contact with the sap is avoided. Before planting, it is necessary to leave the cuttings to dry for 2-3 days. This will prevent rot from developing and enable proper formation of the callus tissue. It is advised to plant the cuttings in a soilless medium, such as peat moss, because it provides an optimal environment for proper root development.
Cuttings should be misted regularly, and the pots in which they are planted need to be wrapped in either foil or a plastic bag to preserve moisture. The bag or foil needs to be removed for two hours each day to provide sufficient air and to prevent excess moisture in the medium. If this step is skipped, molds and rots can easily develop and damage the health of the young, sensitive cuttings. When the cuttings develop a root system, they are ready to be transplanted into soil.
Transplanting
The ideal season for transplanting petty spurge is between early spring and early summer (S1-S3), as temperatures are milder and water supply is abundant, encouraging efficient root development. For location, petty spurge thrives in well-drained soil with sun to partial shade. When transplanting, remember to avoid damaging its root system for optimal growth.
III. Uses and BenefitsÂ
The plant’s sap is toxic to rapidly replicating human tissue, and has long been used as a traditional remedy for common skin lesions. The active ingredient in the sap is a diterpene ester called ingenol mebutate.
A pharmaceutical-grade ingenol mebutate gel has approval from the US Food and Drug Administration for treatment of actinic keratosis.
In Germany, recent studies have linked Euphorbia peplus with the virtual elimination of squamous cell skin cancer.
IV. Harvesting and Storage
Some species of Euphorbia can be cut for fresh flowers or foliage, such as snow-on-the-mountain (Euphorbia marginata), Euphorbia fulgens and Euphorbiaformosana. When harvesting cuttings, remember to wear gloves, as the sap can be irritating to the skin. It can be cut from the base of the stem. Soak the end of the cutting in hot water for 10 seconds to stop the milky sap from oozing. The vase life of the cutting will be about 5-7 days, and some flower food can extend its life.
When the fruits of Euphorbia plants are ripe, they burst and scatter the seeds over a large surface area. In order to harvest all the seeds, the individual fruits or the entire plant must be wrapped in nylon, gauze, or similar material before the ripe fruit bursts and releases the seeds.