To make potting soil from scratch for indoor or outdoor potted plants, partially pre-hydrate Medium Grind (1-2 mm) CLP by placing one rounded cup dry CLP in a five gallon bucket and fill with water- wait 15 to 30 minutes (depends on the temperature of the water) for the CLP to absorb the water and you’ll have a bucket of gel (warm water hydrates CLP faster). Mix with your favorite potting soil at the rate of one part partially pre-hydrated CLP (scoop with a sieve and allow to drain for a few moments) to two parts of your favorite potting soil.
This mix rate is a normal starting point- you should experiment with the species of plants you use and the environmental conditions in which they are grown. High ET-rate conditions will require using a greater amount of CLP in the mix. You can scale this set of instructions up or down depending on your production needs
Typically, this potting soil mix will extend the time between necessary watering by 6-8 times normal in locations with mild ET rates (daytime temperature, wind speed and humidity determine the ET rate). For high ET rates (high day temperatures, high wind speed, low humidity), mix at the rate of one part wet CLP to one part potting soil.
When planting shrubs and trees, you can use these directions and mix rates to add Standard Grind (2-4 mm) hydrated CLP to backfill soil. For large landscaping projects, prehydrate CLP in multiple buckets or use thirty gallon trash containers with wheels), dump the wet CLP on the ground near planting locations to drain excess water, and mix one part wet CLP to two parts backfill soil or half & half to suit the local ET rate, using a shovel as the measuring device.
If the plants are watered by hand with a hose irrigator or overhead spray system which delivers water rapidly, it is best to use medium grind CLP (1-2 mm) rather than the larger standard grind CLP (2-4 mm), to take advantage of the relative larger surface area and more aggressive water-absorbing nature of the smaller material. Note- medium absorbs a bucket of water in a few minutes, while it takes an hour or so for standard to come to full hydration. Therefore, medium grind will more efficiently absorb a greater amount of irrigation water as it percolates down through the soil mix in your plant containers.
However, if the above ground containers are irrigated slowly using a drip system, it is best to use standard grind. Since standard grind will then have the time to come to full hydration, you have the advantage of its relative smaller surface area, losing stored water through evaporation slower than medium grind.
In worst-case scenarios of extremely high evapotranspirative (‘ET’) rates, it may only be practical to use medium grind for above ground plantings (mounded or raised bed), combined with drip irrigation. Mixes of standard and medium are worth experimenting with in your own local high-ET-rate situation to find what works best, balancing the quick water-absorbing quality of medium grind against the longer water-holding nature of standard grind.
High-Performance Soil Mix Recalculation March 2005
Revised January 2016
Realizing it has been years since I calculated the volume occupied by the grind sizes of Hydrosource, and since manufacturing sources vary and have changed over the years, I decided to carefully measure samples of both medium grind (1-2 mm) and standard grind (2-4 mm) Hydrosource, to be certain of the dry measure. I hand-measured 5 lb. bags of medium & standard and found thirteen and one-quarter cups for medium grind and a half of a teaspoon more than fourteen cups for standard.
Calculating backwards from a desired volume of one cubic yard of soil mix combined with partially-hydrated Hydrosource at the rate of two parts soil mix to one part hydrated Hydrosource, I started with the assumption that one cubic yard equals 201.974 liquid gallons. One-third of that cubic yard needs to be partially pre-hydrated Hydrosource mixed at the rate of one rounded cup dry Hydrosource per five gallons of water- one third of the cubic yard is 67.325 gallons. In 67.325 gallons there are 13.465 five gallon containers, each of which requires 1 slightly cup of dry medium grind Hydrosource, which means there will be roughly 13 slightly rounded cups of dry medium grind Hydrosource to start, which equals 5.28 lbs. using the dry measure calculations previously stated.
Therefore, at $3.80 per pound (January 2016 single 55 lb bag price, no bulk discount) in single 55 lb. bag purchase quantities, a cubic yard of soil mix would use $20.05 of medium grind Hydrosource. To make a cubic yard of potted soil mix you would partially pre-hydrate 5.28 pounds of Hydrosource CLP in five gallon buckets (for 13.465 buckets), a heaping cup at a time, or evenly divide five and a quarter pounds of Hydrosource into two 30 gallon trash cans filled with water and gradually combine by shovel in a wheel barrow with 2/3rds of a cubic yard of your soil mix. In a large volume commercial soil mix operation, you can add 5.28 lbs. of dry medium grind Hydrosource to 2/3rds of a cubic yard of soil mix in a large cement mixer capable of handling the cubic yard final volume, gradually adding 67.3 gallons of water (13.465 five gallon buckets), mixing until the Hydrosource takes up the entire volume of water.
If you use a commercial organic product like Kellogg’s Raised Bed & Potting Mix at $10.00 retail per 3 cubic feet bale, it will take nine bags to make a cubic yard which costs a total of $90. When making a high-performance soil mix using Hydrosource CLP, one-third of the Kellogg’s mix ($30) is replaced with Hydrosource CLP ($20), saving $10 per cubic yard.
The high performance soil mix costs less, saves fertilizer, water, labor, and pays for the cost of the cubic yard of material in a single season through the various savings. The additional benefits of 30% earlier time to maturity, significantly higher quality plants (they behave like hydroponically grown), and intrinsically higher crop market value goes directly to your bottom line.
When calculating the amount of standard grind Hydrosource needed for larger-scale landscaping projects, use the figure of 14.78 cups of dry standard grind Hydrosource, which is 5.28 lbs. per cubic yard of backfill for planting shrubs and trees in-ground.
Calculations – Dry Measure Conversion to Cubic Volume
The following measurements and calculations are the ‘best guess’ approximate numbers to use for dry measure CLP, and for hydrated CLP with various final mix rates expressed in cubic feet of soil mix:
• Medium CLP (1-2 mm) = 2.65 cups per pound (5 lbs. hand measured three times, averaged)
• Standard CLP = 2.8 cups per pound (5 lbs. hand measured three times, averaged)
• 1 Cu. Yd. = 201.9740 gallons, liquid
• 1 Gallon Liquid = .004951131687 Cu. Yd.
For soil mix, one-third of the 201.974 gallons in a cubic yard should be made up of partially hydrated CLP gel chunks, or 67.324667 gallons, divided by 5 gallons = 13.4649 five gallon containers of partially hydrated medium grind (1-2 mm) CLP need to be made up – pre-hydrated at the rate of one rounded cup dry CLP per five gallons. 13.4649. I rounded a cup of dry CLP = roughly 14 cups dry CLP. Since MED CLP should exclusively be used for soil mixes, you would therefore need 5.28 lbs. MED CLP per cubic yard.
Comparing this potting soil mix formula to the standard in-ground garden and flowerbed rate of 10 lbs./100 sq. ft., broadcast on the soil surface, assuming 6″ mix depth, the total volume = 50 cubic feet of soil to which one- third the volume is hydrated CLP = 1.85 cubic yards x 5.28 lbs. CLP per cu. yd. yields just a bit less than the 10 lbs./100 sq. ft. rate recommended as optimal for in-ground gardens and flowerbeds.
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