About the genus
Eriosyce are native to South America from the dry southern desert of Peru through Chile, as far south as Concepción, in coastal plains and valleys leading to the Andes mountains, with a number in the Andes themselves. They can also be found in Argentina. Ranging from sea level to 3,000m there is a variety of form and size, from large barrel-like plants such as E. aurata to the almost subterranean E. odieri.
Most plants are single-bodied with natural offsetting restricted to a few like E. aspillagae and a few forms of E. curvispina. Some have a large rootstock which requires a deep pot, while others are fibrous rooted. Body colour is variable with grey or brown forms besides the regular green. Their flowers are equally variable ranging from hummingbird-pollinated to the traditional bee-pollinated.
Eriosyce has a turbulent history of nomenclatural changes and many people still prefer the older generic names of Neoporteria, Islaya, Thelocephala, Pyrrhocactus, Horridocactus and Neochilenia. This is particularly true on the Continent where the labels reflect the workings of Backeberg and Ritter.
How to grow them
It is wise to consider their natural habitat for an indication of their requirements. Most need a frost-free greenhouse, although some will even tolerate a light frost but few will tolerate wet conditions.
Whatever compost you use it must be free-draining, and water should be supplied sparingly. Previous cultivation notes indicate the diverse nature of composts growers prefer, but all recommend adding grit. The use of peat is a constant issue and bodies like the RHS avoid its use. Some growers have excellent results with a pure mineral substrate but compost is only part of successful growing, and watering, ventilation and other features all play a part.
All composts have a limited supply of minerals so the addition of fertiliser is required. One low in nitrogen is recommended, and a fertiliser displaying the feed at 1:1:1 is ideal. Much has been written about South American cacti preferring an acid soil but there is no real evidence for this. What can cause problems is stagnant compost so it is advisable to repot at least every other year.
Many Eriosyce have large fleshy taproots so a ‘Long Tom’ or deep pot is required. The diameter of this pot should not be much larger than the plant itself and the old adage of being able to place your fingers between plant and pot rim is a good one. Standard 2¾in (7cm) or 3½in (9cm) long toms are ideal.
Most commonly available plants are easy to cultivate by following the advice given above, but the genus does have some species that challenge the experienced grower.
Some recommended species:
E. chilensis – Easy to cultivate, this coastal species has many different flower colours, deep pink or white with some nice mixed coloured petals.
E. esmeraldana – Dwarf species, clustering and free-flowering.
E. occulta – A dwarf plant with striking pale flowers. Tuberous roots mean that ‘Long Tom’ pots are needed and careful watering.
E. taltalensis – Fibrous rooted with a dark almost black body. Small pink flowers in winter or early spring. Careful watering required.
E. paucicostata – Often blue-grey bodied and easy to flower with cream petals sometimes infused with pink.
Text and photos: Roger Ferryman, except E. calderana and E. esmereldana, Richard Keyte
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