I'm growing nine Northernlights autoflowers i...

The Answer of MadProfessor is Gemini-Generated

hat should be light stress...Your lighting situation is the most likely reason for the leaf curling.720W in a 120x120 cm cabinet is already relatively strong in the center for flowering. For such a young plant, this is far too much.Symptoms: If the leaves are curling upwards or the leaf edges are pointing up, this is a classic defense symptom. The plant is trying to reduce its leaf surface area to protect itself from excessive light radiation and heat. You should dim the light... If you don't have a PPFD meter, try it at that stage with about 200W for the entire area at approx. 30-40cm distance. Better with a PPFD meter... in this stage you should aim for about 400-550 umol

Your plant looks generally healthy and well structured, but the slight leaf curl you’re seeing (edges lifting upward or twisting a bit) is an early sign of environmental or root stress, not a nutrient toxicity yet. Let’s go through the likely causes and quick fixes, based on your setup: What’s Going On 1. Light intensity Three × 240 W in a 120×120 cm tent (that’s 720 W total) is a lot for small autos at day 19. Even dimmed, the PPFD could be too high near canopy level, especially for young plants. Early LST exposes inner leaves that weren’t used to that much light → they curl slightly upward (“tacoing”) to reduce surface area. Check: If you can measure, stay around 400–500 µmol/m²/s PPFD at this stage (40–50 % power, or ~60–70 cm distance). If you don’t have a meter, try raising lights or dimming for a few days — leaves should flatten again within 48 h. 2. VPD (temp–humidity balance) Temp 24 °C and RH 60–70 % → VPD ~0.6 kPa, a bit too humid for this age. This can slightly slow transpiration and cause the leaves to “puff up” and curl upward. Adjust: Aim for RH ≈ 55–60 % once the canopy fills more. Better air movement also helps stabilize leaf temp. 3. Root oxygen and watering habits Fabric pots are great, but if watering too often, roots can stay moist constantly → oxygen stress → mild leaf curl. Check: Let the top 2–3 cm of soil dry between waterings.Roots love short wet–dry cycles, especially in early veg. 4. Nutrient load At day 19, autos need only light feeding. If you’ve already added PK 13/14 or a strong mix, it could be a bit early. PK products are meant for flowering, not early vegetative growth. Fix: Hold off on PK 13/14 until week 4–5 (when preflowers are visible).Use only your base grow nutrient (and CalMag if needed) for now, around EC 1.0–1.2. Summary of Next Steps Light 400–500 PPFD Dim or raise fixtures temporarily Humidity 55–60 % Slightly lower RH, increase airflow Feed Light veg feed only Pause PK 13/14 Watering Moderate Let topsoil dry a bit between cycles. Bigup ganja farmers, be nice and keep growing greene green 💚✌️

The taco shape your leaves have got is from the light intensity is way to much. There's no need for 3 light, not at this point anyway pal. It does look as if you have lifted the lights recently and the newer growth looks ok-ish.. Good luck