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Look Mum - I can fly
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WATERING
I have stated ad nauseum that sufficient water should be added to the planting medium of a potted plant/tree to maintain a just moist consistency. Neither too wet nor too dry. This is not the full picture of watering requirements.
Water is needed for the metabolism of a plant to continue to work. Water pressure in the plant system is necessary for it to hold its leaves up without drooping. It always moves toward the highest concentration of salt so if the planting medium contains more salt than the top of the plant, water will be drawn downwards instead of up and the plant will probably expire.
Photosynthesis in the leaves converts carbon dioxide and water into sugar and oxygen. Water then, is again necessary for that procedure to take place.
As the weather becomes warmer, the leaves transpire (their equivalent of sweating) to keep the plant cool, making a larger amount of water necessary and this has to be taken into account.
Ideally the water should contain little or no salt and have a pH value of something between 6 and 7.5.
Water direct from the tap has a chlorine content which can be reduced by drawing the mains water and allowing it to stand for a time, when most of this will be released into the atmosphere. The standing water will also assume the same temperature as the air and will benefit from being close to the plants/trees for which it is intended.
Pond and well water can often have concentrations of salt in it and should only be used if tested and found suitable.
Rain-water appears to be the best for our purpose if it is collected and stored out of contact with contaminants. It is usually almost salt and calcium free and very slightly acidic. It is nearly mandatory for Rhododendrons, Camellias and Gardenias.
If you grow Hornbeam, Hazel, Hawthorn, Beech, Spruce, Yew or Cherry be particularly careful about avoiding salt.
A modicum of lime is welcomed by Euonymus, Sabina juniper, Apple and pear, Blackthorn, Oak, Mountain ash and Yew.
Watering through a fine rose gives a more natural application and is less likely to wash medium out of the pot or cause puddling. Leaves may also be wet in this way but not if watering last thing before nightfall when less evaporation takes place. Moisture remaining on the leaves overnight or for a long time can result in fungus growth.
Only if the root ball has dried out completely, is it sometimes necessary to dunk the pot completely in water until all bubbles cease to rise. Peat based mixes are sometimes difficult to re-wet and may need this and even a spot of detergent added for particularly moisture resistant mixes. After being allowed to drain, subsequent watering is best continued from above in the normal way. The passage of moisture from top to bottom of the medium draws air in behind it. Air being necessary for the health of the roots too.
If I have missed anything important out, tell me and I will add it to these ramblings.
My name is Don and I'm a bonsaiholic. If at first you don't succeed, stop growing Serissa.
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Last Login: 7/10/2008 7:00:34 PM
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Stymie - I believe you are incorrect to say, of tap water standing, that carbonates and salt are released to the atmosphere. In fact what will happen is that the water itself will be released to the atmospere in the form of water vapour, and the carbonate and salt content will remain constant which, with the water volume slowly reducingby evaporation, will lead to an effective increase in concentration, not a decrease.
Did I read you correctly? SJ.
Surrey John says "keep pruning".
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Look Mum - I can fly
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Hiyah John. That sounds feasible but I'm not a chemist. Its the way that I read it when composing the article a few years ago. The chlorine certainly reduces. Perhaps it is released as a gas.
My name is Don and I'm a bonsaiholic. If at first you don't succeed, stop growing Serissa.
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Forum Member
Group: Forum Members
Last Login: 7/10/2008 7:00:34 PM
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Spot on Stymie! The chlorine can evaporate, because it is normally a gas, but the carbonates and other salts are all normally in solution so lack the ability to beak through the surface into the atmosphere in gaseous form. Three cheers for GCSE chemistry. SJ.
By the way I'm not getting much time recently to surf, and BH and BG taken together have doubled the necessary surfing time - I'm hoping to be back on with more efficiency soon. Have just started repotting - two larches, both small, (well, one's a Pseudolarix) and will do a windswept Lonicera at the weekend if the whitlow on my finger has receded by then - antibiotics should zap it. It's extremely painful for such a small thing. The Lonicera doesn't yet know it will be widswept.
Surrey John says "keep pruning".
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