Help please

[Dddlondon]

Hi guys I'm growing for the first time 4 plant (critical+2.0) in a 1.2m2 x2m tent with a 600W lumii black hps. Biobizz all mix soil, no nutrients and tap water to adjust ph of 6.3. The plant are 16 days old. We are trying to keep humidity between 50 to 60 % temp 27 degree. One plant looks happy but 3 of them are looking like they having an nitrogen excess. Im trying to understand what im doing wrong and how to fix. Reading some here i thought could be overwatering, could be? Thanks.
Also we keep the humidity up with an humidifier in the middle of the plants.

 

[Herby Paisley]

Hi Dddlondon... At 27c your plants could be suffering from a lil heat stress, How close is the light to the tops of the plants?

 

[Dddlondon]

Hi herby paisley The light is around 70cm to the top of the plant, temperature arrives at 29 at maximum.

 

[Herby Paisley]

Hmm...The height of the light at just over two feet might be too close cause a 600w hps light lets off a lot of heat, and with temps close to the max range of what pot plants enjoy, You might want to try backing the light off them a bit and bringing your temps down to 20c to 24 c and see if that helps.

 

[Dddlondon]

Thanks a lot. I'll try straight away.

 

[NuttyProfessor]

I agree with the light, its a lot, the hps though will make them stretchy, if you get mh with more blues they will sit better , even some big CFL , the more blue lights the better the stems and branches , they will be thicker , make sure you have plenty of fresh air coming in and old air going out

2 of these would ( in cool blue ) give you less heat and proper lighting for veg stronger plants and cost 1/8 of the eclectic your using , then swap in flower to hps when the stretch stops

 

[Dddlondon]

Hi nutty professor, i was thinking already about an cfl light, from lumii, i wasn't just about which voltage, one of 300w would be enough?

 

[NuttyProfessor]

plenty for now

 

[NuttyProfessor]

Blue Light and Plant Growth ,some reading for you​

Blue photons drive the photosynthetic reaction, although from an energy standpoint, one might consider them less efficient than green or red photons because their high energy isn’t fully utilized; some of the energy is essentially lost compared to photosynthetic photons with a longer (less energetic) wavelength. However, at least a minimal intensity of blue light is needed in sole-source (indoor) lighting applications for normal plant growth. In addition, blue light regulates the opening of stomata, which are the tiny openings on leaves that control both water loss and the uptake of carbon dioxide. Generally, only a low intensity of blue is needed in a light spectrum for fully functional photosynthesis. Therefore, indoor lighting (such as in vertical farming) and greenhouse lighting usually include blue in the spectrum.

Generally, blue light suppresses extension growth; plants grown with blue light are usually shorter and have smaller, thicker and darker green leaves compared to plants grown without blue light (Figure 1). In the production of ornamentals, these attributes can be desirable because in essence, blue light can act as a growth regulator. The utility of blue light as a growth regulator is pronounced with indoor lighting and generally has less or no growth-inhibiting effects in supplemental greenhouse lighting. There are some reports in which extension growth is actually promoted under only blue light, although this response seems to be crop specific.