Head gardener Chris Robinson learns to take care as he tends a college cacti collection. Linda Viney reports

The knock-on benefit for the college is that students who are studying horticulture have the opportunity to research the collection made up of 50 different kinds of cacti and 75 varieties of succulent.

Lessons are always learned the hard way as head gardener Chris Robinson soon discovered. Even the fine looking hairs on these plants are barbed and can be difficult to remove whilst the sharp spines can quickly penetrate deep into the skin.

He uses a litter picker to weed in between the cacti and avoid their sharp spines. 'The weeds are easy to remove because they are in a well drained gritty soil mixture recommended for cacti by Kew Gardens and which is akin to Death Valley,' adds Chris.

From November to March the glasshouse is kept very dry, a lesson to be learned with your own cacti. Over watering causes the plants to rot. As the days get longer a liquid feed of potash is given and watering increased only slightly.

'In these conditions growth rate can be quite high and even in a huge greenhouse the plants will try to escape through the roof,' says Chris. 'Some we have to prop up to prevent them breaking. Occasionally we have to cut the tops off and this allows the cacti to throw out branches. Some will grow 2ft in a year. 'We propagate by taking pieces off and allow them to dry out before planting. The important thing is to remember which is the top and which the bottom of the plant,' warns Chris.

In spring the cacti burst into flower turning the glasshouse into a riot of colour. The Queen of the Night is probably one of their most lordly varieties. The flowers come out only after midnight and are gone by morning. 'It is a great place to be on a cold frosty day as you feel transported to another world,' adds Chris Some cacti have their own economic uses too. Particular varieties are used for flavouring for Tequila and others have properties used in health remedies such as aloe vera

To arrange a visit to the walled garden and glasshouse at Bishop Burton call 01964 553000. There are also college open days during the year when you can tour the campus and learn more about the courses on offer.

THE cactus and succulent house at Bishop Burton College, near Beverley was set up 12 years ago by David Chambers the then chairman of the Hull Branch of the British Cactus and Succulent Society. He created a collection of these fascinating plants in a once run-down glasshouse within the college's walled garden after society members ran out of space in their own glasshouses. The glasshouse may have been in poor condition but it had potential. It was huge by amateur standards and heated, with large open beds and a high roof which allowed bigger specimens to grow up to 25ft in height. The temperature during the day ranges from 20 - 25 degrees centigrade dropping to 10 degrees centigrade at night, mimicking the desert conditions of the cacti's natural habitat. All the cacti originate from the Americas including Arizona and Mexico with a few from Africa. The specimens at Bishop Burton College have been supplied by local, enthusiastic members of the society who have free access to the display.