In your garden: The 'Flowers of the Holy Night' that put the red into Christmas

Poinsettias are now as much a part of Christmas as the cake, turkey and sparkling tree. They appear in supermarkets and garden centres from the middle of November and brighten up our homes with their distinctive red colour. But how much do we really know about them?

History

Poinsettias originate from Mexico where they grow into large shrubs. The Aztecs used to make a red dye and a fever control from their leaves. In the 1820s, Joel Robert Poinsett, a US ambassador, discovered some by the road side and took a few cuttings back to grow in his greenhouse. A Poinsettia's botanical name Euphorbia Pulcherrima means "very beautiful".

Legend

According to legend, Poinsettias became associated with Christmas after a poor Mexican child, who could not afford a gift to offer Christ on Christmas Eve, picked some weeds from the side of the road and was told, "even the most humble gift if given in love will be acceptable in Christ's eyes". When she laid the weeds at the foot of the nativity scene in the church they burst into a bouquet of brilliant red Poinsettias. From then on they were known as "Flores de Noche Buena" or Flowers of the Holy Night, for they bloomed each year during the Christmas season.

Facts

The red coloured parts of the plant are not actually the flower but bracts (leaves). The flower is the yellow Cyathia in the centre. They ooze a milky sap like all Euphorbias. Poinsettias represent more than 85 per cent of plants sold at Christmas - more than 60 million are sold in the US alone and there are over a hundred varieties, including shades of pinks, cream and burgundy.

Growing

At Pentland Plants we grow over 80,000 Poinsettias each year for supermarkets, florists, garden centres and our own shop. We buy rooted cuttings in July, pot them and grow them in our glasshouses. They are pinched to make them branch out, spaced regularly, given water, fertiliser, growth regulator and shading to make them change colour by early November. Many British growers of Poinsettias have now stopped due to the huge cost of heating at the coldest time of the year. We're lucky as we have a biomass boiler.

Care

Poinsettias hate cold drafts so keep yours warm, in good light and water it enough to keep the compost moist. If you want to make your plant go red again next year, cut it back to eight inches in March and start liquid feeding. From mid-September to mid-October the plant must be in complete darkness at night, then treat it as normal and you will see the colour changing in November. Poinsettias hate travelling, so British grown plants will probably outlast those imported from Europe. If you buy direct from the grower your plant will go straight from a cosy glasshouse into your living room.

• Carolyn Spray is director of Pentland Plants, Loanhead, www.pentlandplants.co.uk, 0131-440 0895. She is also a presenter on the Beechgrove Garden.