Strombocactus (syn. Echinocactus) is a small group of cacti from Mexico (Hidalgo). Strombocactus disciformis has nice white flowers and Strombocactus pulcherrimus has deep violet flowers. Both species grow extremely slow. A mineral cactus soil and a careful water regime is essential for these plants. Minimum temperatures in winter should be kept around 10 °C. Propagation is done from seeds. In my opinion the Fleischer method is best for sowing Strombocactus. Seeds are tiny and should not be covered with soil. Strombocactus seedlings appear as little green to yellow dots and are very sensitive. maintaining a good air humidity in the first 3-6 months is very important.