About the genus
Ferocactus is a genus of cacti with about 25 species. It is native mostly to Mexico, but occurs also in southerly states of the USA.
It is named for its ferocious spination, with many species having stout, often hooked spines densely covering the plant body.
The size of species varies from globular bodies the size of melons, to massive, over 4m tall, giants one metre across, with most at dimensions between these extremes. In cultivation they make colourfully spined plants, with a few which will flower in cultivation at no more than a small football size, but many having to get larger before flowering may be expected. Even without their crowning glory of flowers they are often good-looking enough to warrant inclusion in a collection. The flowers arise from the centre of the growing point of the plant, pushing their way through the spines often before opening their brightly coloured blooms, from purple, through orange and red, green, yellow or white.
How to grow them
Most often obtained as seedling plants a few years old, they will benefit from repotting into larger pots, in your preferred potting compost, and certainly with a third or half added fine gravel to keep the mixture free draining, so that it does not stay soggy, a sure way to see the demise of these plants. Watering can commence in the spring, to encourage new roots to form and invigorate the plant, but do not water a second time or subsequently until the soil has dried out. Checking with a blade slid down the inside of the pot will show whether this is so and further watering can safely take place. Slow down watering in the early autumn, and allow to dry out completely before there are any low night temperatures and less sunny days, allowing the plants to take a winter rest. A minimum of 4–5°C should be maintained to ensure they do not suffer from UK winter temperatures.
During the spring and summer months they will not need shade and generally grow strongly both in the plant body as well as the spines, which thrive in plenty of sunshine. An occasional feed with a high potash content fertiliser (that designated for tomatoes is fine) will help spur on their development into their potential size and possible flowering.
Apart from the smaller growing species, a few of the larger ones are worth growing for their very attractive and dramatic spines, and even if they take some years before flowering, they are worth their place in a collection for their spines alone.
One worth growing for its outstandingly different appearance is F. glaucescens, with modestly-sized, straight, yellow spines on a blue-green body, yellow flowers and unique white to pale yellow fruit. This species will flower at about 20cm diameter.
The smaller species include F. fordii, with fierce spines and pink flowers. Another which will oblige with green to yellow flowers at small football size is F. viridescens. Perhaps the most obliging of all the smaller species is F. latispinus, usually growing as a solitary plant, and wider than it is tall, with very strong down-curving central spines, ready to trap an unwary finger if handled too casually; it comes with deep pink or sometimes white flowers.
Text John Pilbeam
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