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Search the Community: Showing results for tags 'leaf tip burn'.

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  1. Hi, To cut a long story short, for now I can only get away with a microgrow under my desk. I am growing in a propagation tent 60cm tall and long and 40cm wide. My plants started off fine, but have become very yellow and burned looking and bud growth has slowed as all the fan leaves are falling off. It's way too early to be just because of flowering imho. I would have boosted nutrients, but with the burn at the tips, that'd seem like a bad choice. I've dropped the light level down by 30% as I think the light was too intense at the distance from the flowers, I've also switched to plain correct pH water for a watering as the tip burn has always meant too much in the way of nutrients in previous grow. I have insufficient experience of growing indoors and in strange circumstances like a micrgrow, to make a good judgement about what to do next. Can you tell by the photos what might be wrong? I'd really appreciate some advice before it is too late! (Much more detail below if you want it, or skip to the photos at the end...) ------------------ My circumstances and location mean that it is impossible to grow unless it is very well hidden and camouflaged. I figured I'd see if I could quietly grow indoors under my desk. I realised at the time it was a fairly big ask, with slim-pickings and problems along the way. Anyway... My plants are all turning yellow and crispy. Please see photos at the end and offer any advice you can? More Background I had to make an ultra quiet and small grow room, which I did, using a propagation tent that fits basically under my desk. It's only 60cm tall and 40cm wide. I figured if people can micro-grow in a PC case, I could grow in that. I bought 2 sets of controllable 12cm PC fans for intake and a cooker hood carbon filtered-exhaust. I have a USB deskfan clipped to an internal pole to provide breeze. Temperatures in the tent range from 22c to 29c and RH from 30% - 60%. So far, so not bad - thanks Ona gel. I would have used my rhino filtered inline fan, but on trial it was far too noisy and the filter takes up most of the upper internal portion of the propagator, where the LED light needs to be. I bought Royal Dwarf and Green-O-Matic varieties because they cover a spread of sativa / indica vibes and both stay under 60cm tall. With my fabric pots about 22cm tall and the 100W LED (SF1000) light tied to the ceiling of the tent, I had about 38cm between the pots and the light. I used a mix of about 60% compost - not enriched artificially, 20% Canna Coco Pro and 20% Perlite. I germinated the seeds with the LEDs at about 50%. I LST'd them as soon as I thought it viable, though the GOM was tough and woody from a very early stage and I was loathe to risk breaking it. In hindsight I should have probably risked lower yields and fimmed the buggers at the 4th node perhaps? Anyway, I stepped the light up, bit, by bit until it was at about 90% power. Everything went well for the first 3 weeks or so, despite a little leaf twist here and there, but on the GOM that happened with the very first set of leaves, so I thought, ho hum. Very quickly a few leaves began to show some bronze spots and yellowing / crisping. I had been pH-ing the water to about 6.5 (down from 7.8) and the run-off was about the same, so I figured it wasn't pH. Saying that, a cheap garden-centre probe records the soil pH at about 6.8. I started using some Biobizz Grow at 1/4 strength with each watering and introduced some CalMag at about 1/2 strength. our water is soft, so I figured the brown spots and crisping might be solved with that. Nope. I realised I hadn't been leaving the soil to dry out quite enough. The top inch was dry, but the Royal Dwarf still had leaves dropping down, so I have spaced watering out about 2 days more, flood and drain. The plants are off the saucers, so aren't sitting in water. The leaves are no longer drooping. However, they are getting a bit jaundiced looking. The problem continued into flowering which became noticeable by week 4. The odd leaf was easily removable and I added some Biobizz Top Max and Biobizz Bloom into the mix. The leaf tips were yellowing a touch, particularly on the Royal Dwarf, but both had more fan leaves going yellow and bronze, some at the bottom of the plant, some at the top. Skip ahead to now, around week 6 since germination and I increased the nutrient dose a little. Still only 1/2 of the recommended dose, even for Autos in a standard soil mix. However, many to most of the fan-leaves have now come off. These plants finish in 8 - 10 weeks, so I will soon be at the stage where I'd expect to see some leaves going south during mid to late stage flowering. But this would seem to be a problem. With the flowers now only 10-15 cms from the light max, I have turned the light down to about 75% as that seems a comfortable level and I figured it will reduce the chance of burning, fox-tailing and so on. I just figured that even if I was getting nute-burn (as the tips suggest I am) then the variety of nutrients I am feeding the plants should have sorted out the leave spots and yellowing, but it hasn't. The leaves that are affected were and are at the bottom and top of the plants. They are so short there isn't much difference between the two though, heh heh I would love to know the most likely culprit(s). I'm thinking maybe the safest move would be to water without feed next time (though Biobizz seem to recommend a constant dose of nutrients) dropping the pH to 6.2 or so and turn the light down maybe to 65%? Other Thoughts I've had Could it be a nutrient lockout somehow? Or should I just be boosting the nitrogen nutes, despite the burn I am seeing? In which case, should I try taking the feeding pH down to more like 6.2 in case there is a lockout occurring despite only being a touch high at pH6.8 ? Do I need to boost the cal-mag levels to the full dose recommended by the manufacturer? I felt I was only likely to be a little under, but I suppose it probably couldn't hurt to turn up the dose to full - even if there's already a fair baseline of calcium and magnesium in the water? Is it light burn, if so, why at the bottom of the plant as well? I'm going to get some shorter, wider pots for next go to shave a few inches off the starting height and allow them a touch more headroom. I wanted to try smart pots this time though and couldn't get them in a shallow and wide format. I'm not sure how much I could dim the SF1000 and still give the buds enough light. I mean it feels like I could drop it further, though there isn't uncomfortable feeling heat at bud level. Though the light is a lot closer than it would be in a typical grow-tent with plenty of headroom, it is serving a smaller area and is running at about 70% power. There is a breeze across the top of the plants, but with my hand under the LED for 60 seconds, it doesn't feel particularly warm or even hot. I'm left wondering If I drop the light much more, will it still provide enough light to flower well, if I haven't already completely scuppered my chances? Should I cut nutrient levels back down? I have included some photos of the grow, below. Ending with tonight's affected leaves. Any advice at all would be gratefully received. I have read up a bit, but I don't think reading gives you as clear idea as experience. In this case, I am working with so many compromises and unknowns that I don't honestly know which symptom is strongest and needing tackling most. I know a micro-grow will often have issues simply because of the downsizing, but I am definitely going wrong, I suspect in 2 or 3 places. So any advice will be gratefully received. Outdoor in soil was quite a bit less problematic. ------------------ This First Image is from a couple of weeks ago, before the problem advanced. This is from the last couple of days. Many fan leaves have fallen off and the other leaves are going yellow and burnt in the centre or at tips. Thanks in advance for any help you can offer folks! [Thanks too, to the admins for letting me in!] Midge.