Lime is actually a generic word, much like the word automobile.
There are as many types of lime, or lime with differing content, suited for specific purpose, as there are automobiles.
Consequently, the inexperienced often buy the wrong lime type, use it, and cause damage, or death to their first bulk substrate cased projects.
For immediate buffering of peat, garden, or horticultural hydrated lime is optimal, IMO.
Beware, there are several other types of hydrated lime, which are not optimal. Generally, being 10X stronger than garden, or horticultural grade hydrated lime. They are far to strong for mush/cult purposes.
Horticultural, or garden grade hydrated lime is not that hard to find, at garden center stores, and/or plant nurseries. If you cannot find it locally, a 3 minute google search will get you multiple links to on-line stores that sell it. A 3 to 5 lb box, or bag goes a long way.
The next CRITICAL factor, in the use of horticultural, or garden grade hydrated lime as a peat buffer. Is having the ability to test the resulting Ph. Which requires either litmus strips (inexpensive per tube, or box), or high quality Ph testing probes ($60 to $140).
A standard rule of thumb, established by the well respected RogerRabbit is, 1 teaspoon of hydrated lime (and gypsum) per cup of peat mixed dry, with an equal amount of vermiculite, then hydrated.
That rule of thumb, will generally get the peat Ph into the optimal range. However, I am more cautious than that. Simply because the Ph of peat can vary 1 full point from source, to source. The Ph of vermiculite from differing sources, will vary slightly, also.
So, your peat, may not have the same starting Ph, as mine, or others from differing locals.
I do batch runs of about 100 lbs of hydrated bulk substrate, per 10 tray run. When you calculate the time, labor, and cost of spawn, incubation, bulk substrate, then pasteurization, spawning, then more incubation to get that 100 lbs of hydrated substrate to the fully colonized stage, where a casing cover should be applied.
You have a considerable per run investment in equipment, time, space, materials, and labor.
You can flush all of that down the toilet in an afternoon...by applying a casing cover that has a Ph, outside of the optimal range.
To insure your casing mix Ph is between 7 & 8 (7.5 being optimal IMO),
REQUIRES THE ABILITY TO TEST & DETERMINE WHAT YOUR EXACT CASING MIX PH IS............WELL BEFORE APPLICATION.
I use a Kelway HB-2 probe, as I have one available 
The $10/$20 soil type Ph probes, sold at Home Depot, Lowes, etc. Are not worth the trip to buy one. They are not accurate enough, for this type use.
Ph strips are common place, extremely accurate, and not expensive per tube, or box. They can be found at your local swimming pool or spa supply store in your neighborhood. They are well worth the cost.
Some advocate, once a casing mix Ph is adjusted with lime recommended here. No further, or long term buffer is needed. As the lime will maintain proper Ph, over the life of a substrate tray. I do not disagree. However, being cautious, I add a small percentage of crushed oyster shell FLOUR. As it can do no harm, and serves as double insurance, the proper Ph is maintained throughout the fruit cropping cycle.
Oyster shell FLOUR particulate size is about a 50/50 small grain sand and flour size powder.
Crushed oyster shells (chicken grit size), are worthless. As the particle size is to large to permit Ph buffering over a short cycle, as used here.
Pellet lime, crushed dolomite lime, and pea gravel size lime, are also worthless for buffering purposes, as they pertain here. Those work fine, for garden soil application, over the course of 5 to 20 years.
Edited by Tippinthru (08/07/06 12:51 PM)
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