Of roots and canopies

Many of you will have heard of Marie Antoinette, the wife of Louis XVI of France. While the story is thought to be untrue, tradition has her saying of the starving peasants asking for bread, “Let them eat cake.” Lost her head in the end.  Anyway, she had a favourite tree in the Palace of Versailles under which she often sat to do the things that Queens do. It was an oak tree. A venerable old tree more than 300 years of age which finally dropped its last leaves and was pronounced dead by the Office of National Forests. It had survived the French Revolution, several large-scale wars, and the great storms in 1999 which destroyed 10,000 trees in the park of Versailles, and which laid the groundwork for its death a few years ago. Its canopy had been much reduced and the spread of the head at the end was almost nothing. The post mortem concluded that so many trees had been destroyed that the old oak had become totally exposed and dried out in spite of the water given to it. It’s a sad sort of ending to an old tree don’t you think?  The good news is that the gardeners at Versailles have germinated oak trees from its acorns.  And in true romantic Gallic fashion I expect that in time one of the tree’s offspring will be planted. Unlike Marie Antoinette’s.

The really important thing about this story is that the tree really died because the roots were suddenly exposed due to the canopy being reduced so much. I hinted a few weeks ago that the destruction of roots due to excessive heat was a problem, even when growing normally heat resistant plants like cacti. In the Arizona desert region of the USA cactus plants are baked unmercifully and receive only a few inches of rain every year or two. They survive this by producing amazing root systems spreading over dozens of square yards (or metres). They do this in order to be able to get every drop of rain that falls and store it in their tissue. That is how they survive.  When they are grown in a plant pot they are unable to spread their roots out to get water as they do naturally because they come up against a man-made wall of clay or plastic.

Unless we understand this we might assume that when we grow cactus in pots they only need to receive a small amount of water, and forget that the cactus in the desert spreads its roots far and wide in the search for water. In a five-inch pot they can’t spread very far so you must give them more. How much more? Probably fill up the pots with water every two weeks but make sure that they are in ‘open’ compost. This is the safety net should you get heavy handed, and ensures that no matter how much you give them it will drain off very rapidly. Make sure that there is plenty of drainage (broken pot) in the base of the pots in which you grow them as well. This helps the drainage. The very last thing they need is to have their roots standing in water. Now that will really kill them off.

Your cactus plants will need a lot of sunshine.  They are not lovers of shade and it is a good idea to sink the pots into the ground or some suitable material like fibre so that the roots are not baked in what would amount to a pot roast. Keep their bottoms cool.  The tops are thick skinned and often covered in hair to prevent water loss. Remember though:  Never keep them in the shade and suddenly expose them to hot sunshine. Expose them to the sun gradually.
Until next week may your God go with you wherever you may be.