Euphorbia polygona horrida aka African Milk Barrel

The African Milk Barrel thrives in warm temperatures typical of its native South African habitat. It tolerates temperatures down to -4°C (24°F) and can survive brief drops to -10°C (14°F) if the roots remain completely dry. However, it should be protected from frost in most climates. For outdoor cultivation, it's best suited to USDA zones 9b-11. In cooler climates, grow it in containers that can be brought indoors before temperatures drop below 30°F (-1°C).

Yes, the African Milk Barrel produces small flowers during summer. The plant develops green to yellow-green cyathia (specialized Euphorbia flower structures) approximately 4mm in diameter along the ridges of the stems. The green cyathia coloration is actually a key distinguishing feature from related varieties—Euphorbia polygona var. polygona produces red to deep purple cyathia instead. Plants typically take 5-8 years from propagation to reach flowering maturity.

Euphorbia polygona is perhaps the most morphologically diverse member of its genus, with 12 recognized varieties. The main varieties include var. horrida (glaucous blue-grey stems), var. polygona (green stems with purple cyathia), var. nivea (white appearance), var. major, var. minor, var. noorsveldensis, var. striata, var. ambigua, var. anoplia, var. exilis, var. hebdomadalis, and var. alba. These are organized into two subgroups: the Polygona-subgroup and the Horrida-subgroup, primarily distinguished by stem coloration and cyathia color.

The African Milk Barrel can grow outdoors year-round in USDA zones 9b-11, which have mild winters and warm summers similar to its native South African habitat. In suitable climates, plant it in well-draining soil in a sunny location protected from excessive rainfall. In cooler regions, grow it outdoors during summer and bring it inside before temperatures drop below 30°F (-1°C). The plant must be kept dry during cold periods to prevent root rot. Partial shade can help prevent scorching in extremely hot, sunny locations.

The African Milk Barrel can be propagated through offsets, stem cuttings, or seeds. The easiest method is by separating offsets that sprout around the base of mature plants—use gloves and tongs for safety, separate an offset, let it callus for several days, then plant in well-draining soil. For cuttings, slice a healthy stem, rinse with cold water to stop latex flow, let dry 3-7 days until callused, then plant. Roots typically form within 2-6 weeks. Seeds can be sown in spring after soaking for 24 hours; germination takes 1-2 weeks with warmth or 2-6 months in cooler conditions.

Repot your African Milk Barrel every 2-3 years or when it outgrows its container. Spring is the best time to repot, at the start of the growing season. Choose a pot only slightly larger than the current one with excellent drainage holes. Use a cactus/succulent potting mix or create your own with regular potting soil mixed with sand or perlite. Handle carefully with thick gloves to protect from spines and toxic sap. Allow the plant to settle for a week before watering to let any root damage heal.

The African Milk Barrel is relatively pest-resistant, but can occasionally be affected by mealybugs (white, cottony clusters) and spider mites (causing yellowing or speckling). Treat infestations with isopropyl alcohol on a cotton swab for mealybugs, or increase humidity and use insecticidal soap for spider mites. The main disease concern is root rot from overwatering—ensure excellent drainage and allow soil to dry completely between waterings. The plant may also host the parasitic mistletoe Viscum minimum in its native habitat, though this rarely causes significant harm.

The African Milk Barrel is primarily pollinated by insects attracted to its small cyathia (specialized flower structures). Each cyathium contains nectar glands that attract pollinators. The plant can produce seeds after successful pollination, though many Euphorbias are also capable of self-pollination. In cultivation, hand-pollination may be needed if natural pollinators are absent. The seeds are ejected explosively when ripe, so collectors often place a net around flowering plants to catch the seeds.

African Milk Barrel is a low-maintenance plant that requires minimal attention, making it an excellent choice for beginners.

New growth will sprout from the top of the plant as it grows upwards.

African Milk Barrel’s native range is Worldwide.

African Milk Barrel does best in dry soil and should only be watered sparingly.

The African Milk Barrel is delicate when it comes to soil that is too damp, therefore, it is crucial to select a potting soil that has efficient drainage and doesn't hold an excessive amount of moisture. An ideal soil should consist of a substantial amount of perlite or vermiculite for proper drainage and some organic matter for nutrition. Mixing a few handfuls of perlite with commercially available cactus soil should produce the desired result.

African Milk Barrel requires abundant, bright and direct light. Placing it less than one foot from a window is the best way to make sure the plant receives enough light to survive and thrive. Depending on your region, however, the current weather can affect the placement of the plant in your home. For example, in some areas the sun may be too direct and intense, so it's best to place it farther away from the window. You may also need to adjust your placement according to the season as the sunlight can change intensity over the course of the year. If you live in a region with significant temperature fluctuations, such as a desert, you may need to place the plant a bit farther away from the window to avoid extreme heat or cold. With some care and attention, your African Milk Barrel will be sure to bring you many years of beauty and enjoyment.

African Milk Barrel thrives in dry environments, but if you provide extra humidity or mist your plant, the lingering water on its leaves could create an ideal environment for certain fungal diseases.

The growth of African Milk Barrel is gradual and it doesn't necessitate any additional fertilizers. Replacing the soil in its pot once a year should suffice to provide the plant with sufficient nutrition. It's important to keep in mind that plants derive their energy from the sun's rays, not fertilizers.

African Milk Barrel is poisonous if ingested. We suggest keeping this plant out of reach if you have children, cats, or dogs in the home.

During the cold period, it is common for African Milk Barrel to go dormant and their growth may slow down, so waterings should be spaced out more during this period.