Do You Use Calcium

[Des]

Harry I have used Gypsum in a few pots to gauge its effect on PH and I am finding that the media PH increases to between 7.7 to 8.2 which is too high for Cymbidiums , I have reverted to using Dolomite lime as a buffer and this seems to keep the media PH at around 6.5 to 6.8 (I realize that this could be due to the type or brand of Gypsum available here in SA)
which means that the plants are able to take up all the nutrients they require.

[Suresh Kalyanpur]

Hi John,
How much of Magnesium Sulphate do you add to say five litre of water?
Thanks in advance

[Des]

Originally Posted by Suresh Kalyanpur

Hi John,
How much of Magnesium Sulphate do you add to say five litre of water?
Thanks in advance

I add 5 grams to 5 liters of water every 6 weeks

[Suresh Kalyanpur]

Thank you Des.
Suresh

[orchids3]

Des
It may be your paticular gypsum. I do like granular Dolamite Lime best. Powdered gypsum seems to clog the media somewhat and make the pot retain too much water but I have not found a high pH condition. In some climates the retention of water might be desireable but not mine. It rains a lot here. It had not occoured to me to check the pH of my rain water but I will. One article I read about Marble statues in Europe said that the statues were beginning to deteriorate slowly due to acid rain. That only confirms what we believe. Calcium carbonate (marble is one type)releases calcium when when the water is acid and in the process lovers pH. My pH been slightly lower than 7 around 6.8. My experience confirms the article Steven Early wrote for the CSA Journal about the use of Lime.