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Old October 29, 2016   #22
BajaMitch
Tomatovillian™
 
Join Date: Sep 2015
Location: California
Posts: 84
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I use 4.25 gallon containers that I get from various restaurants for free. It isn’t that easy, though.You have to walk into many restaurants hat in hand to beg for their free empty containers with lids, but it is worth it.

I use Kellogg’s Outdoor Premium Potting mix at $5.97 + tax for 1.5 cu ft., Sunshine Sphagnum Peatmoss at $12.47+ tax for 3 cu ft compressed (yields 6to 7 cu ft expanded), Perlite $14.00 + tax for 4 cu ft., compost from equestrian center at $2.50 + tax for 1.75 cu ft.

The 4.25 gallon Self-Watering Container (SWC) holds 3.5 gallons of wet grow media + ferts plus the volume for the water reservoir.

For the SWC, the basic grow media, I use, by volume,
6.7% compost = 285 grams,
51.5% potting mix = 2,608 grams,
20% peat = 505 grams ,
20% perlite = 304 grams

and the following added ferts:
59.6 grams Vigoro 17-17-17
77.8 grams bone meal
53.34 grams potassium nitrate, KNO3
0.09 grams calcium nitrate, CaNO3
49.3 grams dolomite
1.28 grams calcium carbonate, CaCO3
28.56 grams Epsom salts
¾ teaspoon Alaska Fish solution
35.86 grams potassium sulfate, K2SO4
1 gram monopotassium phosphate, KH2PO4

The above recipe costs me a total of $2.77 for everything for one plant for the complete growing season not including the cost of the seedling. I get the containers for free.If I buy the seedlings at local nurseries, they cost $5 for a packet of 6 seedlings of one cultivar, or $3 to $4 for each a seedling.So, the obvious way to reduce that cost to almost zero is to use seeds from the previous year’s crop or to grow cuttings over the winter from the previous year’s crop.Then use that plant to get cuttings and grow them into seedlings for the next year.That’s what I am going to do.

The above results in the Hydro-Gardens Chem-gro formula precisely. I put the non water soluble Vigoro 17-17-17 in a fert strip circle 1 inch deep from the top surface and at the perimeter of the container.I put the non soluble bone meal, dolomite, and calcium carbonate in a flat layer about 2 to 3 inches from the top of the container.All the water soluble ferts are periodically fed to the plant by way of fertigation spread throughout the 180 day season which begins on April 1st with the planting of a 10 inch to one foot tall seedling.

4.25 drip irrigation container that holds 4.5 gallons of wet grow media + ferts:

For the Drip Irrigation containers’ basic grow media, I use, by volume:
30% compost = 1,636 grams,
35.5% potting mix = 2,305 grams,
16.67% peat = 540 grams ,
16.67% perlite = 326 grams

and the following ferts:
105.6 grams Vigoro 17-17-17
3.4 grams ammonium sulfate
50.4 grams bone meal
48 grams dolomite
0.7 grams calcium carbonate, CaCO3
7.6 grams Epsom salts
44.3 grams potassium sulfate, K2SO4
12.2 grams monopotassium phosphate, KH2PO4

The above recipe costs me a total of $3.11 for everything for one plant for the complete growing season, not including the cost of the seedling. I get the containers for free.


To control costs, I looked high and low for the KNO3, K2SO4, KH2PO4, and CaNO3 until I found a local chemical company that carried this stuff.It cost me about $88.00 for those four items altogether, but I got good volumes that reduced the per gram cost significantly over having to buy them at smaller volumes on the internet plus shipping.The price per gram when purchased in 1 or 2 lb bags would be sky high.Buying in larger quantities locally reduces the cost per gram by 50% to 85% not to mention the big savings on shipping which saves another $30 alone.The one problem with this is that I had to buy a 50 Lb bag of KNO3 – I had no good choice in the matter as the prices were all over the place on the internet.All the chemical suppliers that I found locally only carried KNO3 in 50 Lb bags.

Note that, at least in my experience, various plastic buckets will claim to be a certain specific volume, but the actual volume is often different from the claim. Also, when you irrigate the dry ingredients, they lose about 21% of its dry volume.My recipes account for this so that the wet ingredients come right to the top of the 4.25 gallon container.

It is interesting to note that the cost of the SWC versus the Drip Irrigation Container is very similar even though the volume of grow media in the SWC is 22% less. While the the larger volume of grow media in the Drip Irrigation Container requires more fertilizer, it also contains 30% compost which provides a great deal of NPKCaMgS at a low cost which reduces the quantity of the more costly added ferts.

My goal in life is to find that optimal balance of cost to good fruit yield. I am getting very close to my goal.
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