Gardening – The gift that keeps giving

Red and green are the traditional colours of Christmas, a tradition that may actually date back to the pre-Christian Roman festival of Saturnalia, when wreaths of green holly with red berries would be brought into the home. The traditional colours were maintained in the Middle Ages, revived with emphasis on the German tradition of the Christmas tree in Victorian times and, of course, red was famously appropriated by the Coca Cola company in their redesign of the Dutch version of St Nicholas, our modern-day Father Christmas.

Naturally, in the Northern Hemisphere, Christmas is also in the middle of winter, when any red and green colouring would be welcome. The Northern Hemisphere is also where most of the traditional Christmas plants come from. In Europe and North America the most common species used for Christmas trees are Scots Pine, Fraser Fir and Norway and white spruce.

In New Zealand, we bask in warmth and sunshine (hopefully) over our Christmas break, with the colour provided by our own glorious pohutukawa, while radiata pine is by far the most common Christmas tree species. The only holly we see at this time is plastic!

After radiata pine, poinsettia is the second most common plant sold for Christmas. With vivid bracts in shades of white through pink to red arranged in attractive star shapes, this plant seems tailor-made for the season. In fact it originates in Mexico, where the natural flowering season is mid-winter, just the right time. However, all the plants sold in the Southern Hemisphere are forced to flower out of season by using large blackout curtains to restrict the daylight hours.

One aspect of this trade that I don’t particularly like is the thousands of these plants that are purchased for Christmas then dumped once the colour fades. Poinsettia are a lovely sub-tropical shrub that can be grown throughout the warmer parts of New Zealand, and with their natural flowering being mid-winter when most other plants are quite dull, these are an excellent addition to any garden – you just won’t have them flowering for Christmas again!

The trick is to keep these plants growing well. They are typically grown in peat-based potting mix, which is great for commercial nurseries, but in the home this mix is easily over-watered, leading to leaf drop and eventual death.

Poinsettia don’t like wet feet, so water little and often, rather than soaking the pot or letting it stand in a tray of

When you transplant it into the garden, knock most of the potting mix off the roots and plant in a free draining soil. While you are doing this, look out for white, cottony lumps on the stems or roots; these are probably mealybugs, which often infest this plant. An easy and low-toxicity treatment is to soak the whole plant in a solution of neem oil for a few minutes.

This is safe to use and acts by stopping the insects feeding, so they starve to death (I know, not the best Christmas present for them, right?).

Poinsettia do best in a warm spot, but with some shade during midday. Up against an east-facing wall is ideal, or at the eastern edge of a larger, open tree such as albizia or jacaranda. Avoid planting too near a street light or house lights, as this may be enough to reduce flowering. This vibrant plant mixes well with other sub-tropicals for a lush Pacifica or Bali-style garden, but is equally at home amongst other perennials in a cottage or European-style garden. So this year, try growing your poinsettia on instead of tossing it on the compost or fire heap with the Christmas tree!