• While dilute commercial bleach (sodium hypochlorite) and PPM (Plant Preservative Mixture) tend to be used often as disinfecting agents, other chemicals are available.
• Calcium hypochlorite is often used as a pool disinfectant and can often be purchased at discount stores such as K-Mart, Shopko, Wal-Mart and Home Depot.
• Calcium hypochlorite tends to be "gentler" on some plants than commercial bleach and often will rid the plant material of contamination when other chemicals fail.
• The reason for this is not always understood.
  
• Calcium hypochlorite is messy and smelly. Wear a dust mask, gloves, and goggles. Do not work near food. Read the MSDS before handling it.  This is not a project that is done in your kitchen.

How do you use it (mathematical calculations)?

The recommended concentration for use of calcium hypochlorite is 9-10% for 5-30 minutes. This means 9-10 grams per 100 ml water or 23-25 grams per 1 cup of water (which is about 250 ml), where  1/4 teaspoon = about 1.14 grams.

Most calcium hypochlorite purchased in the discount stores for pool disinfestation have only 75% active ingredients - this means you need to use 25% more to get the proper concentration therefore:

1/4 teaspoon = 1.14 grams x 25% = about 0.86 grams active ingredient

If you need about 24 grams active ingredient in 250 ml of water,

       24 grams * /0.86 grams (per 1/4 tsp)  =  24/.86  =  almost 28

then you need to add about 28  1/4 teaspoons or 7 tablespoons

or    28*1.14 grams = 31.93 grams

(email me if this does not make sense)

How to use it (practical directions)?

• Calcium hypochlorite is messy and smelly. Wear a dust mask, gloves, and goggles. Do not work near food. Read the MSDS before handling it.
  
• Add 7 tablespoons of calcium hypochlorite to 250 ml (1 cup) of water and mix well. Allow to settle and carefully pour the clear liquid into a second container (such as a pint jar) leaving the white powder behind.
  
• Soak your plant material in this solution for 5-30 minutes. Stir occasionally to insure that the solution is getting in contact with all parts of the plant piece. The length of time will have to be determined experimentally. Some plants tolerate a long soaking time and others do not. Test a small piece first and look for signs of browning or bleaching   OR try different lengths of time: 3, 5, 10, 15 minutes, and so on.
  
• After soaking in the calcium hypochlorite is over, move the container to the clean area, and transfer plant pieces to sterile water. Soak in sterile water for at least 5 minutes, or transfer to fresh sterile water after a few minutes. Culture on sterile media as usual.
  
• Check the MSDS for proper disposal methods for your area.
  
• A white film may be left on glassware.  Use a dilute acid like 1 M HCl.  Dairy cleaners (acid detergents) that were developed to remove "milk stone." will also work and should be available at local farm supply stores (Charles Tuttle, email communication - thanks Charles).