HerbalEdu
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Don't hesitate to check my diary week 12 on growdiaries .com https://growdiaries.com/diaries/141634-grow-journal-by-herbaledu
First signs started to show begining of week 11, harvest planned in 6 days at the end of week 13 (veg 3 flo 10)
HPS 250W, 90x60x180 (3'x2'x6'), extractor 220m³/h, 20W oscilating fan between bulb and plant tops
Now, at the end of week 12 (veg 3, flo 9), 3 to 4 phenotypes out of 8 ( 2 phenotypes started showing thoose signs week 11) show deficiency sign wich i think is calcium (seen from bottom of the leaves) and Manganese toxicity (seen from top of the leaves for 2 phenotypes previous week and this week 3 to 4 phenotypes) most prolly because of heat stress.
Excess and deficiencies sign can be seen for leaves directly under the bulb around tent's center, while leaves far from the bulb along the tent border's are not affected.
( 20 cm under the bulb: 40.2°C, on the side of the tent at the same height: 36.5°C, room temperature: 30.1°C)
In conclusion heat right under the bulb in the middle of the tent trigger various excess and deficiencies.
After some research around the net:
Calcium protects your plants from heat stress. Calcium promotes respiration of plant tissue, and stimulates enzymes that protect your cannabis plants from abrupt temperature changes.
(source: https://www.zamnesia.com/grow-weed/316-calcium )
Another article about calcium and heat stress and how plant's cells react (wich, i'm sorry, is a tad bit technical):
not sure but this may suggest the add of calcium won't solve the issue as the cells will still functionning differently due to heat stress even if i'm giving them more calcium.
I still doubt because the signs of excess and deficiency do not appear until the 11th week, not before, and the temperature was about the same in the previous weeks, which may suggest, on the contrary, that the addition of calcium could possibly help the last three weeks of flowering.
Heat and sunlight favour Manganese overaccumulation and stress in crops. (source: https://www.sciencedirect.com/science/article/abs/pii/S0098847216301666 )
Another benefit of a CO₂-rich grow op is that cannabis plants can tolerate slightly hotter temps. Instead of religious dedication to ensuring temps never exceed 28°C with the right CO₂ ppm marijuana can still thrive in the 28-33°C temperature range. In fact, weed prefers slightly higher temps in a CO₂ rich environment.
(source: https://www.zamnesia.com/uk/grow-weed/398-effects-of-co2-on-cannabis-plants )
Currently studying how i can improve thing:
1- adding a cool tube or a more expensive ventilated reflector
2- introduce some CalMag along flowering as i don't use some yet
3- more CO₂ ( CO₂ tabs, absorption by the roots with watering)
4- bigger extractor (switching from 225m³/h to 360m³/h)
5- Switching to LED, viparspectra pro series P2000 (or may be P2500)
Currently more inclined to opt for solutions 1 and/or 2 and/or 3 and/or 4, solution 5 remain a tad bit expensive to my taste plus i won't be able to get the LED 51cm away from plant in flowering like viparspectra recommend but more like 25cm 30cm with the strech i usually experience in flowering, wich should decrease light dispersion on the greatest width of the tent for 4 plants tops out of 8 and may be not enough away from LED for heat.
First signs started to show begining of week 11, harvest planned in 6 days at the end of week 13 (veg 3 flo 10)
HPS 250W, 90x60x180 (3'x2'x6'), extractor 220m³/h, 20W oscilating fan between bulb and plant tops
Now, at the end of week 12 (veg 3, flo 9), 3 to 4 phenotypes out of 8 ( 2 phenotypes started showing thoose signs week 11) show deficiency sign wich i think is calcium (seen from bottom of the leaves) and Manganese toxicity (seen from top of the leaves for 2 phenotypes previous week and this week 3 to 4 phenotypes) most prolly because of heat stress.
Excess and deficiencies sign can be seen for leaves directly under the bulb around tent's center, while leaves far from the bulb along the tent border's are not affected.
( 20 cm under the bulb: 40.2°C, on the side of the tent at the same height: 36.5°C, room temperature: 30.1°C)
In conclusion heat right under the bulb in the middle of the tent trigger various excess and deficiencies.
After some research around the net:
Calcium protects your plants from heat stress. Calcium promotes respiration of plant tissue, and stimulates enzymes that protect your cannabis plants from abrupt temperature changes.
(source: https://www.zamnesia.com/grow-weed/316-calcium )
Another article about calcium and heat stress and how plant's cells react (wich, i'm sorry, is a tad bit technical):
not sure but this may suggest the add of calcium won't solve the issue as the cells will still functionning differently due to heat stress even if i'm giving them more calcium.
I still doubt because the signs of excess and deficiency do not appear until the 11th week, not before, and the temperature was about the same in the previous weeks, which may suggest, on the contrary, that the addition of calcium could possibly help the last three weeks of flowering.
Heat and sunlight favour Manganese overaccumulation and stress in crops. (source: https://www.sciencedirect.com/science/article/abs/pii/S0098847216301666 )
Another benefit of a CO₂-rich grow op is that cannabis plants can tolerate slightly hotter temps. Instead of religious dedication to ensuring temps never exceed 28°C with the right CO₂ ppm marijuana can still thrive in the 28-33°C temperature range. In fact, weed prefers slightly higher temps in a CO₂ rich environment.
(source: https://www.zamnesia.com/uk/grow-weed/398-effects-of-co2-on-cannabis-plants )
Currently studying how i can improve thing:
1- adding a cool tube or a more expensive ventilated reflector
2- introduce some CalMag along flowering as i don't use some yet
3- more CO₂ ( CO₂ tabs, absorption by the roots with watering)
4- bigger extractor (switching from 225m³/h to 360m³/h)
5- Switching to LED, viparspectra pro series P2000 (or may be P2500)
Currently more inclined to opt for solutions 1 and/or 2 and/or 3 and/or 4, solution 5 remain a tad bit expensive to my taste plus i won't be able to get the LED 51cm away from plant in flowering like viparspectra recommend but more like 25cm 30cm with the strech i usually experience in flowering, wich should decrease light dispersion on the greatest width of the tent for 4 plants tops out of 8 and may be not enough away from LED for heat.
