Nitrogen, when and how?

I’m growing in happy frog soil under a 600w blurple. How do I know when they need nitrogen? I’m currently working to flush my soil but I’m debating flowering fairly soon and every time I’ve went to give them nitrogen they don’t seem to like it too much. I have the foxfarm trio and have struggling to understand them. Some people say they need it and some say they don’t. Everyone says the plants will tell me but I am not fluent in plants at the moment lol. Other than some occasional grow big, I’m just giving them pH water with cal mag and they seem to enjoy that. My main two concerns are if I’m slowing them by not giving the nitrogen and how am I going to know when to give them all 3 nutes when I switch to flower. I have a problem with yellowing leaves and brown spots that i assumed was a lack of cal mag which I didn’t have until a month ago, I have not noticed the discoloration spreading but I did give them a little nitrogen with the feeding last night and they didn’t liven up like they normally do when I feed them just cal mag pH water. I never imagined the damn nutrients would be so difficult to comprehend lol. Ive seen the feeding schedule, and when I attempted to follow it based off my plants age, they never responded well at all. Im wanting to learn before I flip them to flower so I can try to salvage something out of this grow.


This is for soil growers. You want to run 1 dose over a course of One week. Just use about 1/3 and or 1/4 strength and you are supposed to feed twice a week. Which means Two 1 gallon doses per week. Then the other 5 days pH water.

Practice makes perfect. The 3 Fox Farms liquid trio is the first 3 on the chart. It has when its a seedling and every week after till you are done growing.

I hope that makes sense. If not ask questions. :+1:


@MrPeat my plants are about 2 1/2 months old currently. I stunted them a few times with mistakes. According to the chart I should already be in flower or priming them for flower but that’s not where they are at. So let me ask it like this:

pH Cal mag = vibrant happy looking plants
pH Cal mag + nutes (nitrogen and/or potassium) = droopy not so happy looking plants.

Is the sad look normal for when you add nutes? I’ve been only giving 1/3 strength when I do give nutes.

I’m not trying to be dense but in all my 2 months experience growing :joy: they seem to not like the nutes. My major concern is when I go to flower they are going to die because I still don’t have a handle on the nutes. I need like nutes for the dumbest of dumb dummies or something. Should I just stick to pH water and cal mag until a problem presents itself? Is the sad look just part of adding nutes? Do I just need to follow the schedule and see if it kills them?

The sad look happens on every grow I have seen. They tend to snap out of it after being watered.

Have @Myfriendis410, @dbrn32, @Covertgrower i’m at a wall to remember who does what. :+1::+1::+1:

@Vance420 We need pictures in natural light. Pics of the whole plant and some leaves you have problwms at. This is a must. :+1:

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I just want the best life for my girls…and to have great bud from my efforts :joy::joy::joy: all of you guys have helped a lot and I’m grateful. I just need to get the nute thing figured out and I think I can be a half ass decent grower.

Will add pics at lights on and see how they appear.

this was before the feeding and they seem fairly happy to my untrained eye, don’t judge my lst attempts lmao.
pic of a bad leaf from 3 days ago which I assumed was from the cal mag deficiency
I’m hoping the brown spots are the mag deficiency and it seems like it’s stopped spreading but will post the sad look in a couple more hours. I run lights out during the heat of the day to help maintain temps.

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With out pictures we would only be speculating.

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Pictures just loaded.
From the looks of it, that’s all old growth, and all new growth looks good.


@Covertgrower added pics to post above yours from 3 days ago but will take more at lights on in normal light.

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Well I have mentioned 3 growers. They could be at work right now. Just be patient. They will also ask for a support ticket with all the informations.

By the way I had a very rough start just a little over 2 years ago. I was going to quit but my sister reminded me of my green thumb. I have done some impressive things with fruit trees, trees, flower garden and a veggie garden. I am glad she reminded me I can do cool grows.

Its about 40 years under my belt. I had one plant that was over 60 feet long aka two main vine brach was 30 feet to each side.


Thanks for jumping in @Covertgrower. :+1::+1::+1:

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@MrPeat no worries, I believe I do a little better when I have a plan and currently I feel extremely stupid about the nutes. Like I understand the concept that plants need these things, more so at certain times of the grow etc but what I don’t know is when yo use them. I was advised that nutes should have been given early and then that they were too small for nutes etc. I think I just need a really good flush and to maybe start again with 1/3 dose of the nutes but at this stage I’m not sure if I just do my nitrogen and cal mag or start all 4 or what lol.

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What nutrient line are you currently using?

Yellow leaves could be sign of nitrogen deficiency.

I would like to spend the time to grab all of the neccessary data and explain this in detail, but I don’t have it right now. I’ve seen way to many posts just like this over the last year, and I’m not sure where they’re coming from. It’s nearly impossible to be successful just feeding a plant calmag or one bottle of a 3 part nutrient package for any length of time. Having an amended soil that will provide nutrients is fine, but when they start to become depleted, a complete nutrient package needs to be applied. Even if it’s in extremely diluted form, that’s fine. But just applying calmag or the “grow” bottle of nutrient line is a mistake in most cases. It will create a situation where the included nutrients will lock out other nutrients, cause ph issues, and ultimately land you right in the place you’re in.

You’re not in bad shape though looking at your pictures. As far as comment about nitrogen, calmag usually has a good amount of nitrogen in it. Imo if your plants are getting worse, your best bet will probably be to flush and reset nutrients. But I wouldn’t just do that until you see problem continue or you have ph and tds data in and out. And don’t worry about the schedule times either. They are setup like that based on minimum amount of time it takes plant to be mature enough to flower. You can pretty much veg indefinitely on late veg nutrient regimen.


@Covertgrower foxfarm trio grow big, big bloom and tiger bloom. My conclusion at this point is that I was unaware happy frog had some nutes in it so I think I had a lockout early. Attempted a flush that wasn’t adequate but got them back Ina decent range. I’m thinking it either has the nitrogen it needs still in the soil or it simply doesn’t need it currently but pH and ppm and the nutes themselves are all new to me and I’m just trying to have a general understanding so I can keep things running smoothly.

@dbrn32 once again I appreciate your help brother. My issues at the moment stem from my own ignorance as a new grower. Once I “get it” I think it will be no big deal like the rest has been. I was under the impression that essentially plants needed nitrogen first, then N and potassium as it neared time to flip them and finally it needed the phosphorus alone with the rest during flower. I just haven’t been able to establish when as it corresponds to my ladies specifically. I wish I had done the trio from early on as some people have told me they feed starting with the first serrated leaves. I’m not sure if that’s just for autos or if it counts for photos as well. I feel like at this point the idea that the 3 nutes are done in separate phases led me to my current problem instead of seeing they needed more of one at certain times etc. Just a learning experience and my own ignorance are the biggest problems lol but I’m determined to succeed, I just don’t want to kill them while I’m educating myself.


I agree; the leaf shown looks like an old fan that got in contact with soil at some point and is dying back. If you had many of these I would actually say nute burn.

Under your lighting and in HF I would not think you’d need cal mag at all this early, but plant has been in medium for 10 weeks. It would help to get a runoff TDS to see how depleted soil is. I don’t see signs of N excess but like stated should follow published grow schedule. FYI the ones I’ve seen are giving ppm in 700 scale not 500 scale. So if in USA don’t trust those numbers without conversion. If using base nutes, you have to use the ratio published but can dilute down to a target TDS. I wouldn’t feed over 750 ppm at this point.


@Myfriendis410 I tested pH in and out as well as tdm on 5/30 and the pH numbers were slightly higher coming out, like 6.13 going in (I know this was too low now especially for cal mag to be taken in) and 6.37 coming out. The ppm was 506 going in and 672, 648, 636, and 774 coming out. I thought that could mean a lockout or it could simply mean the nutes are just sitting in the soil. I’m planning to do a good flush tonight and see what it’s looking like.

I understand. The information that is out there in most places is usually just incomplete. It’s accurate that plants need/use nitrogen early in the grow. But it’s not necessary to shove nitrogen down the plants throats either. Simply having some available is usually plenty good enough, especially for a beginner. Some of the articles out there would have you believe you need to be a chemist or botanist to feed plants, not true at all. In most cases a decent all purpose fertilizer at modest concentration will keep plants healthy throughout vegetative cycle.

Like the old timer says, try to follow schedule as far as ratio of one bottle to the next, even if it’s at reduced strength. This will keep your macro and micro ratios proper regardless of concentration you’re feeding. From there, you should be able to address issues by raising or lowering your ppm or increasing/decreasing feeding intervals without too many issues.


672, 648, 636, and 774 means you don’t need a flush now. I would suggest feeding at 750 ppm using the called out ratio of all three base nutes every other time she gets liquid. Give cal mag on non-feed days to keep nute TDS nominal. When runoff starts to creep up above 1,200 ppm or so it will be time to flush, or when changing the nutrient regimen. (like at the flip)


@Myfriendis410 alright let me ask you this, how do I raise the ppm? Last time I checked my water was around 6.5 - 7 pH and dropped to 5.3 or so after the nutes were added. I use pH up to get it back to 6.5 but have no clue how to raise or lower ppm.

Edit: or is adding a stronger dose of the nutes how to raise the ppm? For instance if I’m adding 2.5 mL of whatever, bump it up to 5 mL?

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TDS (PPM) is a measure of dissolved solids in parts per million and is calibrated in the U.S. to the NACL scale or 500 scale. There are other systems you’ll see like EC or U.K. TDS (700 scale or KCI) but lets stick to that one.

Solution concentration is based on how many solids are dissolved in an aqueous solution. The stronger the solution, the higher the TDS in ppm. (TDS=Total Dissolved Solids)