Planting
Golden barrel cactus can be grown as an outdoor plant or a houseplant.
As an outdoor plant, it prefers a well-drained location, but is not particular about soil type. If your local soil tends toward heavy clay, add sand or gravel to an organic mulch and create a mound to keep your cactus from having wet feet. This is especially important during the cold weather season.
Your cactus will do well in a moderately sunny location, but young plants might need a little protection from midday sun.
Potted golden barrel cactus plants do best in a specialized compost designed specifically for cactus plants. It provides good drainage while still retaining the right amount of moisture for growth.
Propagation
The mature plants need a little winter chill to encourage them to bloom in the spring and subsequently fruit. Each fruit produces thousands of tiny seeds. The seeds can be collected in the fall, then sown in a heated propagation tray filled with cactus potting mix. You can stretch a plastic film over the tray to help retain the moisture and warmth. Place in indirect sunlight or artificial light. The tray should require little watering, but should not be allowed to dry out completely. The young plants will grow best at around 25 degrees C.
Once germination begins, at around 4-6 weeks, remove the film.
Ongoing Care and Maintenance
Once established, golden barrel cactus require very little maintenance. Since they originate from an area where the rainy season is short and intense, followed by long dry spells, they require very little watering. The plants are largely pest free and do not require pruning.
When watering, avoid splashing water onto the body of the plant because this can cause scorching, especially if watered during the day.
Repot container plants in the spring, and feed using a specialized cactus fertilizer during the warm months.
Indoor or outdoor, avoid excessive watering at any time but be especially cautious to avoid it during the chill winter months.