Brown/black colored lettuce leaves

nekbet(6)September 5, 2013

I thought I posted this, but don't see my post... sorry if it shows up as a dupe...

Attached is a picture of my NFT bibb lettuce.. it has some brown/blackish color to the leaves.

It has been in the NFT system for about a week, after spending a week in the nursery channel (flooded channel, basically).

PH is 6.2, just lowered to 6.0
Water is 200ppm (ec x 500 scale), added nutrients to about 1150 now.
Temps are in the mid 70's (air and water).

Any ideas?

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PupillaCharites(FL 9a)

Are the roots healthy, white? EC for the lettuce seems higher than many of the lettuce fans here are using around 700 ppm plus what's in the water, unless you just increased it.

Also if you adjusted the pH down and the problem gets worse, it would make sense the nutes are too strong since going from 6.2 (already low for the starting plants) to 6.0 is going to increase the nutrient use even more, it may be too soon to do that with the high EC solution. Hopefully it all just goes away...

Is this the same system with the fleece spreader? If so I wonder how well the lettuce roots are draining too.

This post was edited by PupillaCharites on Thu, Sep 5, 13 at 16:26

    Bookmark   September 5, 2013 at 4:21PM
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Thanks. The roots look good - white, strong.

I thought lettuce liked low PH - 6ish... are you saying the PH is too low at 6.2 even?

I'm going to add some water and get the overall PPM down to 900, which would be 700 nutes 200 source water.

    Bookmark   September 5, 2013 at 4:39PM
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PupillaCharites(FL 9a)

That's not how I meant it and really the pH is probably not a problem. I'm sure lettuce can be fine even below 6 if you wanted, but my thinking was that most grow formulas are weighted away from phosphorus and it's uptake increases rapidly in what you mentioned. I guessed that is why it is recommended that lettuce be started at a higher pH and the pH lowered as it matures but its just a guess w/o experience to back it up. The thing was if the solution is already too strong, you might not be doing it any favors. So your dilution range range is really the primary thing to get a handle on as you already are doing. When the plants are so small they aren't using as much nutrient so putting high EC upfront is a sort of double whammy since the solution stays high longer under low consumption. A nutrient EC of 1.5 is quoted by Howard Resh.

    Bookmark   September 5, 2013 at 5:20PM
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That makes me think I can turn my ppm up a bit!

    Bookmark   September 5, 2013 at 7:53PM
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PupillaCharites(FL 9a)


You're so close now, just check that you make it healthy to the 5 1/2 oz range by day 35, if that is normal for your variety. If it is you ought to be ok and not need to waste fertilizer. Besides the lettuce will be a little sweeter if it isn't nuked with nutes. The EC range around the 1.5 Resh quoted was like between 1.0 to 2.3 for just the nute part w/o the water ppms. That sounds to me like starting at 1.0 and ending in the neighborhood of 1.5 or at the lowest that gives you a vigorous plant.

You never said your grams per gallon of fertilizer and the fertilizer N %. I would just use that to start around 85 ppm N and finish at about 125 ppm , maybe a little lower in that high EC water you have at least when adding full strength.

    Bookmark   September 5, 2013 at 11:37PM
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PupillaCharites(FL 9a)


Even if you added twice as much water when diluting instead of your plan to get to a 900 ppm measure, you'd end up with and EC from the fertilizer of 1.1 plus the 0.4 of the water which should be ok to rest a little and maybe recover form that dark stuff, just ask Rio, he's below that on the nutes. You can always raise it as the get bigger, if it needs it. But the big healthy roots sound like an excess of Nitrogen.

This post was edited by PupillaCharites on Fri, Sep 6, 13 at 0:16

    Bookmark   September 6, 2013 at 12:10AM
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I am 24-15-36 it takes 29g for 5 gallons per the recomendation of the mfg. but that puts me over 1000 with my 300 ppm water so I am in the 300+ ppm at the moment.
Everything looks good, but I keep having this feeling that I am gonna go out there one day and poof everything dead.

Sorry to hijack the thread. Based on what I have learned 700 ppm would be high for lettuce, but I have read of people adjusting to 800 ppm regardless of water ppm.

    Bookmark   September 6, 2013 at 12:14AM
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PupillaCharites(FL 9a)

Rio, Whoever sold you that fertilizer didn't give you an analysis for the stuff in the box, they gave you the NPK of the pure fertilizer which is less than half of what's in the box. It makes it confusing as heck, but I finally see what you have, which looks to be 9.0-5.7-13.7 +7.2% Ca. The best way IMO to deal with lettuce is base it on nitrogen ppm if the formula is for greens.

From what you said, the 29 grams you put in are probably:
8-15-36 fertilizer 11 grams
Calcium nitrate 11 grams
Epsom salt 7 grams

That gives a nitrogen ppm of 138 ppm (and total of all plant nutrient added fertilizer salts at around 575 ppm, and if it is higher that is for additional non-nutrients in it) and sort of fits with the ppms you've mentioned. I don't think the overall water ppm has anything to do with it, I think you are still doing fine because the stronger nute wasn't necessary with the smaller plants. You had mentioned your water plus pH Down was 600 and you were shooting for 1000 and cut back to do that, which effectively puts your nitrogen around 115 ppm, the correct nitrogen rate for Nursery N ppm. I don't know how you got there with all those crazy high numbers (24-15-36), and in the end right on, at least calculated, but you did it man ;-)

If you go too low, an adjustment up ill easily correct it, with all that calcium in your water and formula you'll never get tip burn. That commercial formula mix pushes the lettuce to be as big as it can, shoving as much nitrogen in, but it looks like what everyone has told you is tending to say the magic number is in the range of the manufacturer ppm for mature lettuce anyway ... 140 ppm N. To do that Rio - the correct amount of your complete boxed mixture is exactly the 29 grams per 5 gallons you quoted which will correspond to an EC of nearlt 2.0 plus the water EC. When they are very small, probably the optimal you can do with the premix is cut back 15%-20%. As they get bigger, see how well it goes even if you stick to the nursery formula (using 25 g per 5 gal). which might contuinue to do the trick just fine according to the comments of others.

I was also reading what a lot of others have said which seem to cut the formula of the mature plants basically to the nursery formula, so I've learned a lot thanks to you guys and when I do my lettuce will start them on about 100 ppm N (The official Nursery formula is 115 ppm N) and jump to 135 ppm N (The official Full formula is 140 ppm N) when they start consuming larger quantities of nutrients measured by topping off with rainwater and watching how the average EC changes each two or three days. Those are Rios formulas which work. If I were him I would not buy the all in one mix though, and instead of using 25 g for nursery, I would cut back instead on the calcium nitrate and same proportional amount of epsom salt. Full strength fertilizer (instead of the premix of fert/Ca nitrate/epsom salt) probably has more desireable micro composition and too much Ca NO3 gives the small plants more nitrate than they need (--which seems to be the problem nek has and it would be great to see nek's NPK and mixing rate to compare both of you--); so it would be good to only cut back on the amendments and leave the fertilizer the same to keep the high traces.

for nek, it would be a great to know your fertilizer product and mix rates, especially to check the N ppm and see how high it is since it seems you started at a quite high EC of about 1.9 for the nutes alone. Some varieties might be a little different and the warmer it is the lower the EC should be.

This post was edited by PupillaCharites on Fri, Sep 6, 13 at 5:19

    Bookmark   September 6, 2013 at 12:56AM
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Thanks for the help so far.
I am using the general hydroponics floraseries. The feeding schedule is here:
They told me to run the first 3 weeks, then stick with the 3rd week until harvest for lettuce and basil.

The nursery channel was around 700ppm, so source water 200 and 500ppm of nutes

The finishing (current) is
120ml gro
90ml micro
30ml bloom
based on their rec of 10ml per gallon of gro, 7.5ml / gal for micro, and 2.5ml for bloom.
FloraGro: 2-1-6 (NPK), .5% magnesium
FloraMicro: 5-0-1, 5% calcium, 0.01% boron, 0.0005% cobalt, 0.01% copper, 0.1% iron, 0.05% manganese, 0.0008% molybdenum, 0.015% zinc
FloraBloom: 0-5-4, 1.5% mag, 1% sulfur

So my basic math tells me:
Nitrogen: 2% of 120ml of gro = 2.4ml + 5% of 90ml of micro = 4.5ml for a total of 6.9ml of nitrogen.
That sound right? How do I convert ml to PPM?

    Bookmark   September 6, 2013 at 8:20AM
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Here is a picture of the roots of a lettuce plant:

Here is a link that might be useful: picture link

    Bookmark   September 6, 2013 at 11:52AM
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Roots look healthy, I don't know about the math, still learning myself

    Bookmark   September 6, 2013 at 2:34PM
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PupillaCharites(FL 9a)

No substitute for knowing the recipe, great! Except you didn't directly confirm (at least in the last post) you have a 12 gallon solution, so just to make sure, 12 is right?

Not exactly how to calculate it though since the specific gravities are up to 25% more than water and it can get complicated if they don't properly disclose, e.g., high chloride and that that is part of the SG. In any case, these appear to me to be the N ppms for the program on your label that you said you are using, W1, W2, W3, W3, W3:

Week 1: 56 ppm
Week 2: 182 ppm
Week 3+: 224 ppm

This is basically the strength for basil and spinach by Week 3, and for GH stockholders too. Too high in everything for lettuce, you are burning them out - confirmed by the brown/black if that began appearing around the end of W2.

Compare to Rio's which is 140 ppm N mature, and the 115 ppm N for Nursery.

An optimal W3+ formula for 12 gallons, which gives 140 ppm N is:

Flora Grow 118 mL (130g)
Flora Bloom 21 mL (24g)
Flora Micro 62 mL (77g)

    Bookmark   September 6, 2013 at 2:56PM
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Man I gotta learn and more importantly understand the math.

    Bookmark   September 6, 2013 at 3:44PM
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PupillaCharites(FL 9a)

So for next time if you want a good Lettuce program:

Mix for 12 gallons NFT res:

Week 1a - same as Flora recommendation -or-

Week 1b (gives 70 ppm N) -
Flora Grow 33 mL (36g)
Flora Bloom 32 mL (37g)
Flora Micro 40 mL (50g)

Week 2 (gives 115 ppm N and great PK):
Flora Grow 81 mL (90g)
Flora Bloom 21 mL (24g)
Flora Micro 55 mL (69g)

Week 3+ (140 ppm N, perfect PK) is:

Flora Grow 118 mL (130g)
Flora Bloom 21 mL (24g)
Flora Micro 62 mL (77g)

I honestly didn't look at the supplements they are recommending besides the basic three part flora and I really don't know if their week one program requires them, so check to see whether they have anything for NPK besides 0. If they get twisted up with other products you don't have or start feeling like it might be snake oil use Week 1b. If I were doing this, I would start with the 1b regimen in this post and after I went through a cycle or two I would look at 1b and 2 and instead of changing then see if I could just make an addition of a little more than Week2 - Week1's nutrients difference to the existing solution. It is not so critical that week 1-2 transition and even Week 2 might be ok to kick off with after you fool with it, so you used one formula for the first two week and the other for the rest.

But please note - these suggestions are not meant to be used with the supplements if those supplements have any NPK value which they probably do since the 56 ppm N off the basic week 1a GH recipe is too low.

    Bookmark   September 6, 2013 at 5:01PM
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Thank you for this!

Yes - 12 gallons is what I am using. I need to confirm I am filling it with 12, and not filling it up to 12 once the system is running (as 6 channels and the drain is prob another gallon or 2 ).

Originally, I looked at the makeup of the general hydroponics bottles and thought I need more bloom off the start...

The lettuce appears happier even since yesterday morning with the addition of water (see pic linked).. just a hint of brown has gone away... hopefully tmrw will be even better.

What do you use for nutrients? I used the GH because folks said it was easy. I think I was reading "lettuce" forums and really it was weed growing... There is no way the PPMs they were talking would work - I wasn't even at full strength with the week 3 yet...

I'm eventually going to have one reservoir for lettuces, chard, kale.. and another for basil and some other herbs... It does appear that the herbs have different needs than the leafy greens.

again, thanks for the help.. I'll be putting in new nutrient water tmrw and will go with this mix... Also have a small reverse osmosis system on order to get the source water down to near 0-ppm so this is easier...

Here is a link that might be useful: picture today

    Bookmark   September 6, 2013 at 6:50PM
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PupillaCharites(FL 9a)


In the middle of something else but just to comment, I don't recall the numbers exactly but just want to catch you - no need for the RO water. You are better off with regular water after the Chlorine is gone. You are actually better off with it and the RO will bring it into the iffy zone. Plus, it will have a little natural buffer with the regular water. It may not be an issue with full strength, but below the Nursery I seem to recall a Cal Mag supplement would be required if you didn't use a reasonably ppm'ed water, hard actually helps.

Yes, your 200 ppm hard water is a required ingredient for your formulation in all W1, W2, W3, since the calcium is too low in all of them without it. Think of the bright side of things - it comes out of the faucet cheap. The formula in RO water is only 55 ppm (W1) to 85 ppm (W3) for calcium. Hopefully, and likely, the water adds over 30 ppm of calcium and topping it off with nutes or water will further add to that.
Calcium in tap of US cities

Be sure to take it from the tap before the water softener.

This post was edited by PupillaCharites on Sat, Sep 7, 13 at 2:46

    Bookmark   September 6, 2013 at 7:06PM
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PupillaCharites(FL 9a)

Be sure to see the comment on RO water.

About your question on a better nutrient system. The Flora Series is rather lousy for lettuce. You need high micros but low nitrogen for lettuce. The moment you start adding micros, the nitrogen sky rockets. It is really a two part formula regarding nitrogen and micros, and unfortunately just not lettuce friendly no matter how I look at it. Maybe someone else sees it differently, but I can't.

You're best bet is to discuss this with Rio, even though his was premixed and set in stone, it is better than yours if he got what I think, for its high ratio of iron, boron and manganese to nitrogen which is not achieveable with this Flora series is a more general scheme trying to do everything. Lettuce is less weedy and herby if you get what I mean, and not bloomy either, an outlier.

If it were me I would do something outside the box if I already had the flora stuff. I would split open the scheme while the manufacturer scowled 'what are you doing', by putting Flora Grow in some temporarily forgotten place, and just buy some potassium sulfate which is a cheap fertilizer, to basically stop Flora Bloom from forcing of high phosphorus, which is really the only thing Flora Grow is there to do. So I think (without carefully checking) that dumping the Flora Grow and relying on Flora Micro to supply all nitrogen I'd be very happy with my micronutrients levels and my new three parts would be sulfate of potash, Bloom for phosphorus, and Micro. That would be the perfect lettuce formula and the only but might be two cents worth of epsom salt from the corner drugstore. That's the qualitative recipe...

Don't be discouraged. The easy solution is what Rio did and your Flora nutes are excellent for other crops. They will probably do ok for lettuce even at low micros since the plants can adapt and the ingredients are all high quality, we might try to increase a little more of the Micro, basically for each gram up, 2.5g less of Grow but it will start to go out of whack and compromises get made as in all these mixing schemes.

    Bookmark   September 7, 2013 at 6:06AM
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Alrighty... an update..

I drained the finishing channels reservoir (I have nursery too, which is much lower PPM and seems happy) and refilled with your week 3 recommendation above.

PH was around 6 and PPM 750 but it seemed as expected...

Since last week when I added fresh water (that sat for a day to get chlorine out) the leaves are looking much better. They have slowed growth a touch, but hopefully this new nute mix will add some growth.

I think the next round I will not do so much basil. Just more leafy greens - to that end, I have kale, chard and more lettuce in the seedling tray now.

Based on what you said about calc and nitrogen - and a few youtube videos and threads...
I went ahead and ordered this from -
Masterblend Tomato Fertilizer 4-18-38
Calcium Nitrate
Magnesium Sulphate

I am getting some tip burn with the high-PPM and tap water solution...

I'd like to get an analysis of my water... and/or, use RO water and add the calcium to get a known quantity as an experiment. I'll probably setup two channels (18-22 plant sites) in a smaller reservoir for this soon...

thanks again for the help.. I'm going to ping Rio and see if he has any notes I can piggy back on.

    Bookmark   September 9, 2013 at 10:42AM
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PupillaCharites(FL 9a)

That formula is fine with the added benefit of being able to make a nursery formula (when you aren't forced to compromise because of having a graduated mix of plant maturities together from the same res).

That guy who made some of those Master Blend videos ought to get a commission he's made so many customers for that formula. I think he is using a 12/12/6 gram per five gallons if I remember right. For lettuce, & MBT 4-18-38, it would likely be an improvement to use (Calcium nitrate/MBT/epsom): 10.7/14.4/6.7 for 5 gallons, or 35g/26g/16g and that gives very close N~140. This would closely match Rio's commercial lettuce formula.

OK for RO water or the tap you've had. Don't know about normal tip burn, that is usually a Calcium deficiency in hydroponic solutions by using waterwith unavailable calcium but counting on it.

    Bookmark   September 9, 2013 at 2:22PM
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PupillaCharites(FL 9a)


(Calcium nitrate/MBT/epsom): 10.7/14.4/6.7 for 5 gallons, or 35g/26g/16g and that gives very close N~140.

should have been

(Calcium nitrate/MBT/epsom): 14.4/10.7/6.7 for 5 gallons, or 35g/26g/16g and that gives very close N~140.

    Bookmark   September 9, 2013 at 2:26PM
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