Do I fertilize seedlings?

[AKmark]

I hired a new grower, and this guy is good. He is an old hippy that says he is interested in growing produce rather than......... After a brief interview, I seen an honest humble man standing there, and hired him. Wow, this guy knows his stuff, very technical and he certainly knows advanced growing technique, he is spouting stuff that goes right over the top of my head.
At any rate, I am sitting 20 plants aside for him to show me his work, I will keep the plan zipped until I see positive, worth mentioning results. He is making sense on paper, so we will see.

[AKmark]

These were grown on the program you are now on Ricky

[RayR]

Originally Posted by Ricky Shaw

RayR,

Thank you Ray, that's what I'm here for, to check my work. So, I have two Hanna testers, both calibrated recently. The PPM reading is 1266 on one and 1256 on the other, and my source water is 50-60. They each have PH at ~ 6.2 and the uS values are 2530 and 2540.

What checks is that I'm using the small batch measuring directions which say, "For 1 gallon, swap out the “pound” for “tsp” below. Meaning 1/2 tsp 4-18-38, 1/4 tsp each Mag&Cal and it comes out close on the meters. Matter of fact I have to add a pinch of fert to get it up to strength.

I think I'm using the meter correctly. If not, why would would the reading be close when I follow mixing directions and not way off? The user videos for the Hanna are not very in depth and I want to get this right. Comment are welcome.

I'm no expert on hydro but understand the basics. I'm an organic grower outdoors but I may mess around indoors on a small scale with both organics and synthetics during the winter There is a lot of confusion with TDS because there are different conversion factors that different nutrient manufactures have adopted and TDS meters typically base their conversion factors fixed at the ppm 500 (NaCl) scale, the ppm 700 (442) scale or sometimes both can be displayed. Some meters don't use the fixed conversion factors but instead use the more accurate non-linear conversion factors.
So for everybody to be on the same page we have to know the ppm scale that is being used.
The recommended ppm is 1200 + source water or an EC of 1.6mhos + source water (equivalent to 1.600µs/cm or 1.6ms/cm). That would mean to me that he recommendations are based on the PPM 700 scale. 1.6 X 700 = 1120ppm, that would be a little higher using
the non-linear factors. In the same ballpark anyway. For a meter that displays the 500 ppm scale it would read about 800ppm instead of 1200ppm. TDS is so confusing.

[Zenbaas]

Originally Posted by RayR

I'm no expert on hydro but understand the basics. I'm an organic grower outdoors but I may mess around indoors on a small scale with both organics and synthetics during the winter There is a lot of confusion with TDS because there are different conversion factors that different nutrient manufactures have adopted and TDS meters typically base their conversion factors fixed at the ppm 500 (NaCl) scale, the ppm 700 (442) scale or sometimes both can be displayed. Some meters don't use the fixed conversion factors but instead use the more accurate non-linear conversion factors.
So for everybody to be on the same page we have to know the ppm scale that is being used.
The recommended ppm is 1200 + source water or an EC of 1.6mhos + source water (equivalent to 1.600µs/cm or 1.6ms/cm). That would mean to me that he recommendations are based on the PPM 700 scale. 1.6 X 700 = 1120ppm, that would be a little higher using
the non-linear factors. In the same ballpark anyway. For a meter that displays the 500 ppm scale it would read about 800ppm instead of 1200ppm. TDS is so confusing.

I always assume people are using the 500ppm scale unless they state otherwise.

[Ricky Shaw]

Ray,

Si I should be mixing to 800ppm instead of 1200ppm?

I have a Hanna 98129 and its set on .5 conversion and temperature corrected, the factory defaults. My current readings are 1258ppm, uS 2511, and 6.2ph.

What doesn't square here is this would make the mixing directions wrong, they come out very close to 1200ppm as I and pecker have both noted.

[AKmark]

Ray has a point there, we are not getting a elemental PPM reading with our meters, that is what is throwing us off. Our meters do not read actual PPM like we seek. So we just do as we are told by the big boys, or not. I believe it has to do with the atomic weight of oxygen being calculated in the fertilizer on their end, and other items than NPK, CA Mg, being measured in the TDS on our end/ fillers. I am reading about this, and hopefully will understand it good enough to explain someday.

What ever happened to sticking the plants in dirt and slinging MG on them? lol

[RayR]

Originally Posted by Ricky Shaw

Ray,

Si I should be mixing to 800ppm instead of 1200ppm?

I have a Hanna 98129 and its set on .5 conversion and temperature corrected, the factory defaults. My current readings are 1258ppm, uS 2511, and 6.2ph.

What doesn't square here is this would make the mixing directions wrong, they come out very close to 1200ppm as I and pecker have both noted.

That's the way I would interpret it since the EC is given as 1.6. You're feeding at 2.5 EC. I just don't know, you have to contact the nutrient manufacture and get some clarification. Also is that nutrient concentration for early stages of growth or for mature flowering plants.? Seems way high for early veg anyway.

Originally Posted by AKmark

Ray has a point there, we are not getting a elemental PPM reading with our meters, that is what is throwing us off. Our meters do not read actual PPM like we seek. So we just do as we are told by the big boys, or not. I believe it has to do with the atomic weight of oxygen being calculated in the fertilizer on their end, and other items than NPK, CA Mg, being measured in the TDS on our end/ fillers. I am reading about this, and hopefully will understand it good enough to explain someday.

What ever happened to sticking the plants in dirt and slinging MG on them? lol

Yep. There is no way an electronic meter can give you a precise reading of Total Dissolved Solids or tell you what elements and compounds are dissolved in the water. The only way to do that is with some time consuming and expensive lab work. But you don't really need that kind of precision.
EC is an absolute measurement, it tells you the Electrical Conductivity of a solution. Pure water doesn't conduct electricity but with dissolved electrically charged ions and molecules it will conduct electricity. Salts by far have the greatest impact on EC since salt molecules disassociate into charged ions in water. Other soluble molecules that don't disassociate in water into ions can also impact EC if they carry a + or - electrical charge but to a minor extent. Molecules that have a neutral charge won't impact EC at all.
A TDS meter is just a EC meter with one or more conversion factors built in to give you an estimate of ppm. There are actually many different conversion factors for different applications but for hydro and general horticulture the most commonly used are the NCl (ppm500) and the 442 (ppm700) scales.
It's no wonder the Europeans throw TDS right out the window and use only EC.

[Ricky Shaw]

Ray, you're a genius! I'll have more to report tomorrow.

[Ricky Shaw]

An excellent catch Ray, thank you.

Going with the theory that if equations are involved, somebody probably made a chart, I found dozens of them. This one is good because it shows three conversion scales and some manufacturer's that use them. (Hanna .50/Eutech .64/ Truncheon .70)

Our directions say, 1.60 mhos + source water. Sliding down the EC ms/cm column on the left we can see that corresponds to 800ppm on a Hanna set on a .5 conversion.

My answer: 800ppm + 56ppm source water= 856ppm

[Ricky Shaw]

Plant A, the regular leaf, seems unfazed with the two weeks of energy drinks. Bea has drying tips on the earliest true leaves. Possibly over-fertilization, but nearly all the houseplants have it here from the dryness. Had not worked with potato leaf plants before, I like'em. They seem more expressive than regular leaf and not just talking dry tips.

A new mix has been made, 850ppm using the .5 conversion, ph 6.39 unadjusted, mhos 1.679

[AKmark]

Ricky, I do not think that is fertilizer burn, the leaf does not look dark green enough, and burn usually leaves a dark brown burn on the tips. That almost looks like the beginning of damping off syndrome.
I had some real problems during fruiting in one greenhouse using a low ppm like that, I labeled it a Potassium deficiency, yellow shoulder, blotch ripening, it was the most horrible ever. I knew Potassium deficient leaves never fix the damage, but had no idea the fruit cannot either. Every fruit that was set was just garbage, I had to go through a complete cycle of fruitset before good fruit came off those plants. I literally hauled over a 1000lbs to the compost shed
We can assume several factors affect our numbers between you and I, I got the best results following the recommended PPM on the HG bag, my EC was way higher than it should have been. A discrepancy, but in the wrong direction. I had the state horticulture guy here, we were so confused, he was going to contact HG.
At any rate, I follow results, and for me it is the ppm on the bag.

[Ricky Shaw]

Ricky, I do not think that is fertilizer burn, the leaf does not look dark green enough, and burn usually leaves a dark brown burn on the tips. That almost looks like the beginning of damping off syndrome.
I had some real problems during fruiting in one greenhouse using a low ppm like that, I labeled it a Potassium deficiency, yellow shoulder, blotch ripening, it was the most horrible ever. I knew Potassium deficient leaves never fix the damage, but had no idea the fruit cannot either. Every fruit that was set was just garbage, I had to go through a complete cycle of fruitset before good fruit came off those plants. I literally hauled over a 1000lbs to the compost shed
We can assume several factors affect our numbers between you and I, I got the best results following the recommended PPM on the HG bag, my EC was way higher than it should have been. A discrepancy, but in the wrong direction. I had the state horticulture guy here, we were so confused, he was going to contact HG.
At any rate, I follow results, and for me it is the ppm on the bag.

It's evident that seedlings not only will withstand sizable doses of nutrients, but can most obviously benefit. I think as I get more comfortable with the instruments and mixtures, I want to ramp up and find that sweet spot.

[Ricky Shaw]

Paul Robeson 33rd day from seed, 8" tall, 13" span, I'm thinking these would be about ready to go. Very happy with the results for a fluorescent shop light, near nursery quality.

I'm going to do some Big Beef from a couple different sources next and run elevated nutrient levels on half and keep a log. What could be tougher than Big Beef, right?

[Cole_Robbie]

I think I'm going to start my early indoor seedlings underneath a south-facing window, and make a little hot box around the window. I'm still going to use lights, but what I'm going for is a little bit of UV-light hardening in the seedlings. I never seem to be able to get them hardened off enough when started indoors. However much foliage I grow indoors, the sun just burns it all off when the plant goes to the greenhouse. Plants recover, but I'd like to skip that step.