🌱 Week 2 – Vegetative Growth
09/27: Started the day noticing chlorosis on some leaves. The pattern matches an iron deficiency: interveinal chlorosis mainly on the newer leaves. After checking, this seems to be caused by a nutrient lockout, consistent with the high substrate pH since the beginning of the grow. Lesson learned for next time. Performed a heavy flush with 20 L of water per plant. Runoff dropped from EC 1200 → 500 and pH 7.1 → 6.7. From now on, I’ll water with enough solution to get ~20% runoff each time instead of just ~250 ml. Will also lower input pH to 5.6–5.7 to gradually bring substrate pH down into range. Noticed that some plants have started to give off a light smell 🌿.
09/28: Each plant watered with 1 L at pH 5.6, EC 950. Solution included 3 ml/L CalMag + 0.8 ml/L Coco A + 0.8 ml/L Coco B + 1 ml/L Deeper Underground. Runoff EC not measured (since heavy flush was done yesterday). Runoff pH still unchanged, same as yesterday (~6.7). Yesterday I lowered the light, today increased it back to 13.5k lux. Chlorosis is still advancing, hoping successive irrigations will help bring substrate pH down.
09/29: Watered again but with 500ml this time. Solution (same recipe as yesterday) at pH 5.6. Surprisingly, runoff pH rose higher than yesterday, now at 7.0, with EC 700. Light intensity increased to 14.5k lux.
09/30: Watered with 500 ml at pH 5.6, EC 1050. Solution included 3 ml/L CalMag (new bottle — seems to add more EC than the old one) + 1 ml/L Coco A + 1 ml/L Coco B + 1 ml/L Deeper Underground. Runoff measured EC 700–800, pH 7.0. Since the flush, stems have thickened significantly 💪.
10/01: Watered with 1 L at pH 5.6, EC 1200. Solution included 2.5 ml/L CalMag + 1 ml/L Coco A + 1 ml/L Coco B + 1 ml/L Deeper Underground. Runoff measured EC 650, pH 7.0. Substrate pH still not dropping, but plants are growing at a good pace. Only two plants continue to show chlorosis, while all show a noticeable thickening of stems this week.
10/02: Significant vertical growth observed — most plants stretched about 8 cm in the last 3 days. Watered again with the same solution as yesterday, but only 500 ml per plant. Input pH 5.6, runoff pH still at 7.0, EC 600–700. Chlorosis persists, and on one plant with symptoms, small brown spots appeared, suggesting a possible manganese deficiency. Also noticed what look like early pre-flowers (tiny pistils) on two plants, though it feels early for day 20.
10/03: Watered with the same solution as previous days (pH 5.6, EC 1200). Runoff remained stable at pH 7.0, EC ~600–700. Based on uptake, I plan to progressively raise input EC until EC in ≈ EC out. Gradually increasing VPD range, target for Week 3 is 1.0–1.2 kPa.
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📝 Week 2 Summary
🚩 Main challenge: persistent high runoff pH (~7.0) causing chlorosis, initially resembling iron deficiency but later showing signs closer to manganese deficiency (brown spotting).
Heavy flush reduced EC, but pH correction is progressing slowly.
Plants responded with strong stem thickening and rapid vertical growth (+8 cm in 3 days).
Aroma starting to appear on some plants 🌿.
⚡ Light stabilized around 14–15k lux, with adjustments to avoid stress.
🌱 Despite issues, most plants are vigorous, only 2 showing stronger deficiency symptoms.
➡️ Plan for Week 3
Irrigation: Increase input EC gradually until it balances with runoff (~EC in = EC out). Maintain runoff at ~20% each watering.
pH management: Keep input pH at 5.6–5.7 to push substrate down from current ~7.0.
VPD: Raise target range to 1.0–1.2 kPa for optimal transpiration.
Light: Hold intensity ~14.5k lux, slight increases only if no stress observed.
Monitoring: Track chlorosis spots closely — see if new growth improves once substrate stabilizes.
Pre-flowers: Keep observing possible pistils.