Purple stems, brown spots - early flower

[AllMenWillBSailors]

Hi AFN
Been reading here for a while, but my local forum died and I need some help, so I finally created a user here.
A little sad that first post should be in the infirmary
Photos (at the bottom) are not great, camera kind of broken - will get new one next month.

Problem:
Second grow and starting to see issues of same nature as I had in my first grow
Ap. 1 week into flowering, some leaves gets brown spots that progressivly spreads, stems become purple and whole issue will gradually spread (first grow gave good quality 150g(5.3oz) @150w LED so no disaster).

However, for this grow I changed Lights, Medium, strains, ph-down brand and nutrients -so quite surprised to see same type of issue.
Noticed it yesterday (day 27) - just one leaf - but heavy spotting and purple steam - removed the leaf since it was the only one and thought -well maybe it is a disease afterall, better avoid spreading.
Today I have 3-4 leafs on each starting to show the same and with stems turning purple.

NOTE: please ignore the drooping leaves, they do this the last few hours of lights-on, then an hour into next lights-on they are back to being raised/upright.

Medium/grow method:
Indoor/cabinet/soil/LED/Autoflowers - not organic.
DIY grow-cabinet. Slightly less than 2x2feet (W58cm x L57cm x H192cm)
2 x 11L (2.42gallons) Fabric pots w. Soil - mixed w. ap. 25-30% perlite (washed) and a bit of "BPS Root explosion" (Mycorrhiza).
Soil assumed to be ap. ph 6.3 (Label says 5.8-6.5, but I added "half a fistfull" of "garden lime")

Feed and supplements used:
Common Tomato fertilizer (NPK 4-1-7) at ap. 10-25% strength – total < 7ml in each Pot from day 16 onward.
Canna PK13/14 -added once - at day 28 at ap. 20% dosis - ap. 0.8ml each pot.
Have bottle of BioBiz CalMag -but have not used.
Hand watering, tempered and after "damp off" -Ph Downed, currently ap. 1.2 L every second day for each pot - nutrients every second/third watering.
Not watered to runoff at any point.

water source:
Tapwater – ph-downed to ranges 6.2-6.5 (ph down was Grow-version of "Hydroponics of Holland PH-Down" – now switched to Bloom-version of "Hydroponics of Holland PH-Down") - Yes it is applicaple for soil.
Checked the water-report and found it had no chlorine (trace amounts) -pretty “hard water” though.
Can supply details of water report.

Strain/age:
Two autoflowers @ day 32
1x FastBuds Orange Sherbert Auto
1x Alien vs. Triangle (maybe - gifted, is not directly from Mephisto - literally could be any auto)

light used:
Kingbrite LED 240w - currently @160w (bar based, not QB)
Schedule: 19/5 on/off -Yes i am weird, sorry.
Details: LM301H + CREE XP-E2 660nm -Spectrum 3500K
Current distance 50cm/20Inches

Climate:
First 2 weeks:
Humidity 66%-76%(lights off) and 65%-55%(lights on)
Heat: 19c (lights off) and 23c (lights on)

Week3 and forward:
Humidity 56%-63%(lights off) and 46%-54%(lights on)
Heat: 20c (lights off) and 26.5c (lights on)
Carbon filter + inline vent @ ap. 145m3/hour
2 x 120mm pcfans for circulation

Additional info:
Friend of mine use almost same setup with no issues over three grows:
Exact same soil-mix.
Water PH/hardness is comparable.
Light is almost the same as mine.
Nutes are the same - but suspects he feeds more heavily.



While I am more than a little annoyed, I am not in a panick - as last grow turned out great (yield/quality) with exact same issue....
(assuming this will spread/expand to same extend).

Right now my prime suspects are:

• Underfeeding?
• Pk13/14 too rough on them? (but they only got ap 08.ml in 1.2l water once each!)
• PH-Issue: but how would that happen - if soil started around 6.3 and all waterings have been in the 6.1-6.5 range - yes the PH could be slightly off, but hardly significantly so?

Do not have Ec-meter (and REALLY dont want to get one -question will result in rant, sorry)
Have tossed PH-probe as it was crap, and are back to using ph-drops (have two sets from different vendors and they agree, so feel confident w. those)

Any other information needed, just ask and I will try to provide.

Thank you for any help!

 

[Bruce Campbell]

What brand of soil did you use?

Do you know if it had any other amendments / starting nutrient content? Or, was it just peat that you added perlite and lime to?

Edit: Also - What does your water quality list for calcium content?

(Some list calcium (only) along with other individual metals, some report "calcium hardness" (along with other hardness measurements), and others provide just a total TDS / EC value.)

Edit 2: Are those hydroton / clay pebbles on the top layer of the pots?

 

[AllMenWillBSailors]

What brand of soil did you use?

Do you know if it had any other amendments / starting nutrient content? Or, was it just peat that you added perlite and lime to?

Edit: Also - What does your water quality list for calcium content?

(Some list calcium (only) along with other individual metals, some report "calcium hardness" (along with other hardness measurements), and others provide just a total TDS / EC value.)

It is a common local brand of "gardening soil", sold everywhere around here.
"on paper" it is a little "too hot" for autoflowers, but many here use it with succes.
To protect the young roots, I added a little "non-hot" seedling soil around the jiffies when planting (about amount of 1½ beer-can)
It is not an ideal soil, but it really should be "ok".

I have a picture of the soil inventory, but it is not in english, so ask if anything is not clearly understandable from the picture. Amounts are per cubicMeter M3:

As for the water - it is HARD - just ask my bathroom-tiles
They report both the "hardness" (in dH -and the amounts of Calcium/Magnesium)

The top-dressing are called "leca marbles" they are made from burned clay I think, extremely common here and should be completly neutral/harmless- they are used for drainage in the bottom of pots or as top-dressing to limit evaporation and make soil less available to insects.

Appreciate any suggestions.

 

[Bruce Campbell]

I'm thinking it's low P / high Ca.

I may not be doing the conversions correctly, but your soil actually looks like it's pretty low in starting nutrients - I'm getting about 0.03%-0.01%-0.03% NPK by weight. For comparison, that's about 1/10 of a fox farm's blend.

Your feed seems low, too, and the high Ca from your tap water may be making things worse. High Ca can reduce P availability in the soil, but usually doesn't completely remove it until very high pH. Your ph-down will add some P, but you probably have a lot of room to increase the feed.

I normally try to balance K:Ca:Mg in a 4:2:1 ratio. Based on your tap water and the Canna PK alone, that means you'd want to be up around 2.5 mL/L of Canna PK just to balance out the K and Ca. You'd then want to add about 500 mg/L of epsom salts to balance out the Ca and Mg. And, that would be at each watering to remain in balance.

That's a big jump, so I'd go slow - but my point is, I think you have plenty of room to increase your P/K. Another better option may be to switch to RO/demin to remove the high Ca from the equation entirely, if that is possible for you.

 

[namvet25]

Thankyou for the detailed info,thats the way everyone should do it.Was your plant dry when you took the picture? You might have lockout so i would give her some cal/mag and a little nitrogen Next grow try using Promix soil mix or some other brand name and PH the water Also i would remove any lower leaves that are touching the soil or are not getting any light.

 

[AllMenWillBSailors]

I'm thinking it's low P / high Ca.

I may not be doing the conversions correctly, but your soil actually looks like it's pretty low in starting nutrients - I'm getting about 0.03%-0.01%-0.03% NPK by weight. For comparison, that's about 1/10 of a fox farm's blend.

Your feed seems low, too, and the high Ca from your tap water may be making things worse. High Ca can reduce P availability in the soil, but usually doesn't completely remove it until very high pH. Your ph-down will add some P, but you probably have a lot of room to increase the feed.

I normally try to balance K:Ca:Mg in a 4:2:1 ratio. Based on your tap water and the Canna PK alone, that means you'd want to be up around 2.5 mL/L of Canna PK just to balance out the K and Ca. You'd then want to add about 500 mg/L of epsom salts to balance out the Ca and Mg. And, that would be at each watering to remain in balance.

That's a big jump, so I'd go slow - but my point is, I think you have plenty of room to increase your P/K. Another better option may be to switch to RO/demin to remove the high Ca from the equation entirely, if that is possible for you.

Thank you, I really appreciate it !

Very good point about the water and high Ca.
I just took a quick look at some posts on cannabis and hard water, and clearly it is a bigger issue than I thought.

I will need to read up on that and see what my options are, as I think this is my main problem.
Considering my local weather, rainwater might be possible, just got to figure out what I would need to add then.

Increasing the feed does not sound too scarry, as I have been going very light so far. My concern was that the slight yellow tips meant I was already giving "enough".

As for the soil, I think something must be off in the conversion, simply because the growers I have talked to here, consider it somwhat "hotter" than "commercial Autoflower soil" like BioBiz LightMix - also it would be weird for a commercial "all-round gardening soil" to be extremely low in nutrients.

Might be back with more questions when I have read up on the hard water issue

 

[AllMenWillBSailors]

Thankyou for the detailed info,thats the way everyone should do it.Was your plant dry when you took the picture? You might have lockout so i would give her some cal/mag and a little nitrogen Next grow try using Promix soil mix or some other brand name and PH the water Also i would remove any lower leaves that are touching the soil or are not getting any light.

Thanks!

Yes it was dry to the point where I would have watered, except it was minuttes until "dark time". I will water as soon as I have read up on the "hard water issue" before I decide on the what to add to the water (or even source some non-tap water).

Yeah, am close to "giving in" and buying autoflower specific soil next time.

Usually would remove low/yellow leaves just thought if I had some kind of lockout, I would let it suck out any remaining stuff drom those. Since with the clay-marbles I am not too affraid of them rotting?

 

[AllMenWillBSailors]

So, an update.

Based on the great input here, I did some reading on "hard water issues" (too much Ca) - and it really seems to fit the bill.
I am quite sure this is my main issue (and was last grow as well) - yes, also some underfeeding but I think that is less critical and easier to fix.

So late friday night I turned to damage control - 10mins before closing time, I managed to buy all eight 1-liter Distilled water bottles from local grocery store (Lady at register gave me a weird look ).

Watered to slight runoff (ap. 1.5l each pot) w. Distilled water, Ph-adjusted to 6.4 and with 3.5ml/l NPK 4-1-7 and canna PK 13/14 1ml/l. (former of which has a bit of Magnesium)

As soon as it is dry enough, i plan on giving 2l in each pot of 75% distilled w. 25% tap-water and ap. same PH & feed as above - expecting at least 25-30% runoff - and hoping this will help get rid of any excessive Ca buildup and "solve" any lock-out, esp. of potassium and magnesium.

Long term, using bottled distilled water is obviously silly, so starting to collect rainwater and looking for cheap manual RO-filter/pump (like the ones used for hiking).
I guess something like 33% tap-water to 66% RO water would be suitable longterm - except for lack of magnesium, so also ordered epsom salt.
Might try my hand at a single initial "foilage feed" once the epsom arrives, to circumvent any lockout at roots and to make Magnesium available asap.

Does this make sense or am I missing anything?

Compared with friday, there are a few more purple steams but no significant new spots. So hope things are heading in the right direction. Will know in a few more days.

 

[Bruce Campbell]

Sounds like a plan!

 

[EP3]

Hope it all keeps in track for you m8.

Cheers EP3