Maximum Yield Cannabis USA October/November 2018 | Page 68

To further examine and compare costs, each expense can be sepa-
rated into individual categories such as rent, utilities, lighting,
equipment, nutrients, etc. If these costs are calculated separately,
then they too can be compared for improvements or lack thereof.
For example, if an additional $100 in nutrient expenses improves
production or quality by more than $100 in value, then it is gener-
ally worth it to continue the practice. Costs on durable goods
(those that aren’t used up during the grow) can be spread out over
their expected lifetime. If the lamps for the lights are used for four
runs, then each run bears 25 per cent of the cost of the lamps. If the
lamps are changed every other grow, then each grow must support
50 per cent of the cost.
Getting Value from Nutrients
A little math comes in handy when making nutrient selections
as well. The NPK listing on nutrients indicate the percentage by
weight of nitrogen (N), phosphorus (P) and potassium (K).
What this means is nutrient solution A, made with a fertilizer
with a value of 5-0-0 that is applied at 15 milliliters (ml) per
liter, should have the same nitrogen content as nutrient solu-
tion B with a value of 15-0-0 applied at 5 ml per liter. It is the
final amount of nitrogen in the nutrient solution that counts,
not how concentrated the original nutrient was. If 15 ml of
nutrient A is 20 cents cheaper than 5 ml of nutrient B, then,
all other things being equal, it should be the better choice.
When deciding which to use in the future, it will come down to
whether nutrient B is worth an additional 20 cents per treated
liter. To find out for sure, test a few plants using each nutri-
ent. Record the nutrient expenses used to grow both sets and
calculate the GPD at harvest. Not only should the more expen-
sive nutrient produce more product, but enough above and
beyond to cover the additional expense to be worthwhile.
Calculating Lighting Costs
The same can be calculated for electricity and lighting costs.
An examination of your electric bill should tell you at what
rate you are charged for electricity, and that can be used to
calculate how much it costs per day to run lights.
To calculate lighting watts per square foot, calculate the
square footage of the garden area. If 8x1,000W lights are used
in a 10x20-foot area, then 8,000W is used to cover 200 square
feet. So, 8,000W divided by 200 square feet is 40W per square
foot. A change in lights or an increase of wattage per square
foot should also show a commensurate increase in production
to be cost effective.
Once such numbers are recorded and calculated, then
decisions can be made based on results. If a change in
gardening techniques improves results, then consider
keeping the change. If it doesn’t, consider discarding it and
returning to previous methods. Improvements to the garden
should result in documentable improvements in production
or quality to be cost effective.
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