Jacks Professional 5-12-26 + 15.5-0-0, slow flower initiation?

Hello Cult of Jack!

Im a member of the cult of jack too. I love paying pennies for my nutrients vs hundreds of dollars. Quick question to seasoned jacks users.

Since switching to jacks, ive noticed my budding initiates later. (I see white hairs in 2 weeks vs under 1 week with other brands) I suspect its from me continuing to use 15.5-0-0 during flowering. My ppms for start of flower are 700-750 and I work it up to 900. This includes 140 ppm of the tap water.

Anyone else notice this. Or can suggest a tweak?

You've got jacks 15.5-0-0? That's calcium nitrate double salt! Yes you keep using that!! That's your main source of both nitrate and calcium!

It's analogous to GH "micro" bottle and calmag+, which both use calcium nitrate as their main ingredient.

Here's a tip: You can get the exact same 15.5-0-0 calcium nitrate double salt for $2.60 a pound or 7 dollars for 5 pounds at cropking.

http://www.cropking.com/HydroponicSupplies/index.php?main_page=index&cPath=264_265

Maybe you're using slightly too much if flowering is delayed? Try using a bit less. You can also order some mono potassium phosphate (KH2PO4) to use to boost P a bit. It's 0-52-34 NPK, but be sparse with this! Even flowering plants don't need nearly as much phosphate as they do N, K, and Ca.

I think its the same price with cropking. I buy the 25lb bags. So it comes to $35 for 25 pounds on both sites. But it would be cheaper if I was only buying a pound. So thanks for the link.

Some of my sativas can take the high ppm's like nothing. No problem. big buds. great smell and fantastic weight. but then some of my indicas get more leafy, budding is delayed, buds form smaller, and they finish weeks late. Is that from a general over feeding? Or is it the nitrogen being present in high amounts? I know it has something to do with the high value double digit npk.

I used a nutrient calculator (hydrobuddy) to figure out that if you add 1 part calcium nitrate and 1 part Jacks hydro 5-12-26 (by mass), you will get:

an N2O5:K2O ratio of 1:0.59:1.27
a K2O:Ca:Mg ratio of 1:0.73:0.24 (good ratio, very similar to hoagland solution which is 1:0.71:0.17)

What proportions of calcium nitrate and 5-12-26 are you using?

EDIT:

If you use 1 part calcium nitrate and 2 part jacks 5-12-26:

N2O5:K2O ratio of 1:0.94:2.04
K2O:Ca:Mg ratio of 1:0.37:0.24 (too much potassium per calcium I think)

This is how I do it.

I use PPM to measure the amounts.

I start by making 900ppm solution.
900-140(140 tap water) = 760

I add 450ppm of 5-12-26 so the total with tap water is now sitting at 600ppm. I then add 300ppm of 15.5-0-0. So my total ppm now is 900.

From that I reduce by adding water until my ppm is 750. Thats usually where I start to flower on a 2 foot tall plant in dwc.

For flowering, try using:

10 parts 15.5-0-0 calcium nitrate
7.5 parts 5-12-26 Jack's hydro mix
2 parts mono potassium phosphate (KH2PO4)

http://www.cropking.com/HydroponicSupplies/index.php?main_page=index&cPath=264_268

Hydrobuddy shows this to have:

N2O5:K2O of (1 : 1.01 : 1.37)
K2O:Ca:Mg of (1 : 0.72 : 0.18 )

It estimates that 10g,7.5g, and 2g will give an EC of 1mS/cm in a 4 gallon DWC.

You should really download HydroBuddy and use a 0.1g digital scale for measuring dry nutes. I input the formula for Jack's 5-12-26 manually into the substance database, but you can select "yara calcium nitrate" since that is the 15.5-0-0 double salt 5Ca(NO3)2.1NH4NO3.