Flowering stage – watering and nutrients

I am about to begin my flowering 12/12 stage on my first ever grow, tomorrow.  I know enough to stop using my veg nutrients and get some flowering nutes.  I bought some 10-54-10 Bloom Builder from the advice of a nice lady at a local nursery (about my ‘tomatoes’).  I didn’t want to ask too many questions … I had planned on beginning them on the flowering nutes immediately …?  Is that a good idea?  I think I have read to use just water during the first and last two weeks of flowering and the nutrients in between, but I can’t find that info again despite an extensive search.  Can someone comment on that?

Also, I have read about PK 13/14.  What is this exactly and how do I use it … or should I?

Edited Feb 11, 2012:

Carrying on from Campo’s comments on the Cloning Advice post regarding watering (I thought this might be a better place to discuss it… I copied/pasted your comment, hope that is OK)

Campo’ comments – “are you sure that you are not over watering max ? with experience you will know by the weight of the pot but for now here’s a useful tip which is pretty fool proof: 1) get two pots the same as what you are growing with and fill with the same dry medium you’re using for the plants 2) weigh one with some kitchen scales 3) take the other and water until the water starts to creep out of the pot 4) drain off until it it stops dripping, then weigh

the difference in weight will equal the amount of water retained by the medium for example, if your dry pot weighs 4 kilos and the watered pot 5 kilos this is a difference of 1 kilo which converts to 1 Liter of water now next time you water wait until there is 25% or preferably less of water retained by the medium so for this example I would water when the pot weighs 4.25 kilos or less

The weight of the plant is negligable at this stage (100g)

Overwatering is an issue when growing under LED grow lights … for this reason I switched from soil to coco – perlite. Next time I suggest you do the same, or DWC (deep water culture) or any other type of hydroponic system such as NFT.”

I am so confused!  Let me explain.  I am back and forth on whether I am over or under watering.  Just want my girls to grow good and stromg!  lol

I thought I might be overwatering, but have been very careful to make sure they get good and dry before I water.  I haven’t gone as far as weighing the pots (no scale), but I do take note of the weight of a dry pot and after I water.  I also stick my finger down the side … I’ll water when the top is completely dry (1-2 inches) and my finger tip all the way down feels mild dampness.  I used to water them twice a week with about 600-700 ml of water, but I already noticed the droppy claws of the under growth.  I thought it might be too many nutes, so I reduced the amount and even watered once with straight water.  After about 3-4 days the top leaves which “always” stand up and look healthy, would begin to droop.  Each time after I watered them they stood right back up looking healthy.  I thought I was getting the hang of this, but the lower leaves still looked straggley and limpy.  I only have small 2 gallon pots (partly to help control the plant size) and I am sure the roots are right to the bottom.  I was  noticing that the water never reached the bottom drain holes, so I decided to start using more water … 1 liter each per plant … I am thinking “maybe I am actually underwatering them” … ?   I have been watering them 1 liter each every 3-4 days for about 2-2.5 weeks.  Now just a tiny bit of water comes through the drain holes.

Now, just to confuse me more and make me consider underwatering again … I came home from work Thursday last week and they were all VERY droopy!!  The plants had been watered on Tuesday (4 liters split between 5 plants cuz I only had 4 liters),   As usual my biggest plant droops first but this time it looked just dreadful! (see below)  The soil was dry, pots light so the only thing I could think of is underwatering, although that made no sense … I had watered them only 2 days ago and have never seem them as sad as this!  I gave them all one liter and within 3-4 hours, they were all standing back up strong and healthy … except if you look under the canopy and the smaller under growth.  I removed some of the big fan leaves around the bottom which seemed to just hang there covering the lower vegetation (they were droopy too, some laying flat on the soil) … 2-4 per plant … hoping maybe some more light exposure will help, but the top canopy is so thick (especially with all 5 plants close together) that I am not sure it will.

I did make one change this last week.  Until now I was using demineralized water from a bottle (mineral salts < 10 ppm) treated by reverse osmosis.  It was getting too expensive, so now I am using tap water that I leave sitting for 24 hours so the chlorine can evaporate.  That is all I can think of … maybe my frequency of watering is OK but I should cut back the amount to perhaps 500 ml?


9 thoughts on “Flowering stage – watering and nutrients

  1. Campo Cultivator says:

    hello m8 keep on feeding the veg nutes for the first week of flowering and around day 10 to 16
    change to you flowering nutes
    speaking of which tomatoes are not cannabis and the needs are different it would be worth your while getting some canna terra flores or some such specialist cannabis flowering feed
    pk 13/14 is a potassium/phosphorus boost which is a one at most two shot application that enhances flowering at week 5 in a 8 week genotype don’t worry about it! as when growing with soil you have to watch for toxicity and salt build ups play around with it when you have a grow under your belt and have everything else down pat
    hope this helps

  2. Maxwell Turner says:

    Thanks Campo! I actually didn’t tell the lady it was for tomatoes (I do use that as a code word sometimes! lol) I said it was for my wife and had no idea what she was growing, just that she wanted maximun bloom. Didn’t know that there was cannabis specific food … I’ll go hunting for some.

    Btw, I replied to your overwatering post over here instead. Seemed more appropriate in this thread.


  3. Allen Buddington says:

    HEY MAX!AAnd campo!during flowering ,if plant is doing well you will need to water much more frequently.When you find you cannabis nutes make sure it has t least magnezium along with other micro nutes ..muey importanta!!! :-)

  4. Weed Widow says:

    yeah he is right with nutes mg is important just add some epsom salts to supplement every week or so
    lol don’t worry about that under watering episode at least you know when to water now :)
    I remember I did it to a 3 meter tall plant outdoors last year lol when I walked into the field my heart hit my stomach its amazing how quick the recover when they are given water pheww
    heres a link to some top nots nutes which deliver to your region I think :)
    hope this helps


  5. Maxwell Turner says:

    My local hydro-shop has Canna Terra Flores … thought I’d go with that. Also I saw they sell Canna Coco and the coco nutrients. From everything I have read, coco is a far better medium than soil so that is definately they way I will go next time.

    Still trying to figure out why my under growth is so limpy … it is only on 3 plants … I gave those 3 half of normal on the last watering to test again if I might be over-watering. And yes, it is amazing how fast they recover. I was sure they would … what make me scratch my head the most is how these plants don’t seem to have a pattern to their need for water.

    I gained about an extra week or so due to a last minute super cropping attempt, but 12/12 is coming soon! Can’t wait to reap my rewards!


  6. Maxwell Turner says:

    I still have the problem of very happy, healthy top leaves and droopy, straggly lower/inside secondary vegetation.

    I thought over watering might be the issue, but I have repeatedly left the plants until the upper leaves wilt before I water … I have tried giving them a lot of water often … I have tried flushing them with water only … no change!! No yellowing or spots so I don’t think it is too many nutes … just quite droopy … not healthy looking like the upper leaves.

    I am now wondering if my small 2 gallon pots might be the problem … maybe the roots have out-grown their square footage? I purchased some 5 gallon pots and was thinking of transplanting them, but I’m not sure if I should at this point.

    I am only a few days into flowering … first, does anyone think going to bigger pots will help with my problem? If it will, any tips on how to get an 18 inch plant out of the pot without causing too much trauma?

    I bought a moisture meter and although water usually just barely trickles out of the bottom drain holes when I water, 2 days after watering, the middle is ‘medium’ and the bottom couple inches are ‘dry’. I thought the bottom would dry out last. Is that telling me something?

    Btw, I have used some epsom salts in my water this time (one tsp per gal).


  7. Maxwell Turner says:

    Well good news. I think I have finally determined that I was under watering. I guess I hadn’t paid attention and the water hadn’t been running out of the bottom of the pots and the bottom few inches remained mostly dry for a couple weeks. I found this out when I probed with my moisture meter a while after I had watered … the bottom was still dry. I gave each plant another litre each (twice as much as normal) and the pots trays filled up this time. A few hours later, they looked 100% better.


  8. Mikey p says:

    I have also just started this fine hobby and have found that air pots are a pretty cool thing. More watering, but my plants get more o2 at the roots and no problems with being pot bound.

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