Need help with Light intensity for my seedlings

Discussion in 'First Time Marijuana Growers' started by Aricel, Nov 27, 2022.

  1. #1 Aricel, Nov 27, 2022
    Last edited: Dec 2, 2022
    I have a Mars Hydro TSW2000, currently it's height to (top part) of the seedling is approx 60cm, and it's light intensity is 60%. However I feel like it might be too low? The plants seem to be a bit too tall. My notes:

    ~Seedling approx 4-5 days old (after they broke soil)
    ~Amnesia zkittlez auto
    ~watering the seedlings approx 130ml every 2-4 days (going by if the soil dries up)
    ~I noticed very minor (barely noticeable, possibly the start of further yellowing) yellowing on one of the plant's tips, light stress maybe? (no clue lol)
    ~150mm Extractor with carbon filter and ducting (no oscillating fan)
    ~Air out 24c, air in 22c, temperatures inside/around the pot approx 24-26c

    Any tips would be appreciated, this is my first real grow with proper equipment.

    +Update: I buried the stem a little bit and bought an oscillating fan and plan to get a ph tester. Plants seem good aside from odd waving of the leaves, can't really pinpoint the cause of this other than possible light stress or ph imbalance (judging from the info I could gather off google).

    Attached Files:

  2. The seedlings look like they are stretching. You need a light meter (!) I personally use a Dr.Lux meter and start my plants at 20,000 lux (at the canopy).
    There are some apps you can use on your phone that emulate a light meter, some members say are pretty good.
    • Like Like x 1
    • Agree Agree x 1
  3. #3 Aricel, Nov 27, 2022
    Last edited: Nov 27, 2022
    Will try the app now

    ~The app got me around 21000lux at the canopy, and some other numbers that I have ne clue what they are
    • Like Like x 1
  4. seedlings at this stage need more heat than light, 72-79F is good best 77f
    I do use a heat plate and a low end floro, works well

    you not mentioned the soils but cutting with 30% perlite at this stage and this current result will work well

    check the link: Nutrient Burn

    good luck
    • Like Like x 2
  5. My plants are around 25-26c (77-79f) so that seems good, soil is Lightmix Soil with extra perlite. From what I can tell my set-up seems good I was just worried about them being a little stretchy as a lot of videos I watch on autoflowers they don't grow as tall as mine, although it might just be my strain or maybe other factors coming into play so much to take in when growing still learning
    • Agree Agree x 2
  6. Im in europe and for years have suffered bad mold, to counter that I use stretchy lights/ 2400 kelvin or hps thru out my grow,
    having slightly stretched plants allows the air to circulate amongst the crowded leaves and flowers,

    tho later a couple of weeks of cool white is good to encourage normal growth,

    forget the perlite then if you are happy with what you got

    not to be confused where plants have not enough light and stretch full time to get that required light, note the light color of 2400 kelvin stimulate the auxins/hormones, making the plant seem slightly stretched, cool white light 6500 kelvin does the opposite and makes squat plants

    good luck
    • Like Like x 2
  7. An old trick is to lightly flick the plants or have an oscillating fan that can swing some air currents on them. This will help a lil to reinforce the stem. Not sure what tropism is at work here (thigmotropism?). Also, you can bury the plant deeper when you decide to transplant. I put a bit of rooting compound on the stalk when I do this.
    that is good.
    which is why I see nice plant growth off 5000K. I bought a couple older Samsung lm561c strips for $3 (per 2' strip) and they work so nice for this.
    I wouldn't recommend this; shorter internodal space can be controlled by pruning but long internodal space is not so easily treated. Anyhow, defoliation and training ftw.
    that is good, but I should point out that idk how accurate those apps are. I use my light meter quite a bit more than I ever thought I would...
    • Like Like x 1
    • Agree Agree x 1
  8. I do not plan to transplant as I'm not experienced and messing up on that would delete my yields (since im on autoflowers) so they in the final pot from the get go

    Might try set up a mini fan somehow i'll figure that out in the morning xD
    • Like Like x 1
  9. I don't understand the seedling stretching when it's getting hit with 180w @ 60cm/24 inches. For the first 7 days of life, my auto seedlings are under a Mars TS 1000, necked down to 75w @ 46cm/18 inches with absolutely no stretching. I'm baffled.
    • Like Like x 2
  10. Yeah I dunno either was a bit confused myself hence why I came here for some advice, I read somewhere that they might have just released hormones that make them grow and it's not about light intensity but I have no idea how legit that is/how it works.

    ~I should also point out that I think they peaked in height (or I hope they did) as since yesterday and checking again now I'm fairly sure they haven't grown any longer
    • Like Like x 1
  11. That's what's puzzling. I know when there is insufficient light, the seeding releases a hormone causing the cells in the stem to rapidly elongate in an effort to get closer to the light. But with your Mars set at the parameters you describe, light shouldn't be a problem. You might try this @Aricel - add medium to within 4cm of the cotyledons for support and as @trojangrower suggested, add air circulation to strengthen stem and root system.
    • Like Like x 1
  12. @Vee makes a valid point that should be recognized.
    color temp much more important than some realize.

    ...but you have a similar light so dropping down the extra 14cm might be the ticket. I would note the app's lux reading for future use.

    and the app... again, its a secondary go to and shouldn't be considered as a valid point. Additionally, the amounts of photosynthetic active radiation (PAR) measured by lux instruments (except for quality quantum meter$) is only a general illuminance; it doesn't pick out the color intensity and only gives a ballpark value; so using a lux or phone app is not the best for determining accurate values. But if you get to know your device, and record it for future use, it will be useful.

    yes! add some soil, bury them stretchers
    • Like Like x 1
  13. tropism
    1. The turning or bending movement of an organism or a part of an organism in a particular direction in response to an external stimulus such as light or gravity.
    I prefer the word photo - morphism, bending to the light, tho tropism means any thing that moves the plant
    I thought I was the only one who buried deep, agree about the light apps, I still drive Lux and convert to PAR when I have too, by x1.5=

    we swim the same direction

    • Like Like x 1
  14. Update: I buried the stem a little bit and bought an oscillating fan and plan to get a ph tester. Plants seem good aside from odd waving of the leaves, can't really pinpoint the cause of this other than possible light stress or ph imbalance (judging from the info I could gather off google).

    Attached Files:

    • Like Like x 1

Share This Page