Please help - Switched to LEDs ==> slow growth, no budding!

[Ritualis]

Hi guys,
I’m quite desperate right now so let me skip to the point (at the bottom you’ll find tl;dr)
Setup and performance until now

• Seasoned indoor grower (~ 6 years)
• Setup: 8x4 (240x120 cm) grow tent
• Lighting: 2x 600w HID (Lumatek, Adjust-a-Wings reflectors)
• Method: SCROG
• Strain: Dinafems’ Moby Dick (8 plants)
• Medium: Soil (Plagron) in classic ~10 gal (40L) pots
• Feeding/nutrients: Canna Terra (Vega, Flores, Rhizotonic, Cannazym, PK13/14)
• Grow cycle: From clones to 75% filled screen 18h MH cycle for about 3 weeks and 2 months of 12h flowering.
• Performance: 1 – 1,25 g/W

I wanted to expand operation and due to HID electricity/output ratio turned to LEDs. As preassembled LED systems are very expensive, I did my fair share of research and at the end decided to do it myself.
This is my new setup

• Setup: 8x4 (240x120 cm) and 6,6x4 (200x120 cm) screen (w/o growbox)
• Lighting: 2 x MeanWell HLG-480H-48A each driving 8 x Samsung HinFlux L09 SL-B8V4N90LAWW 3000K Lm301b diode LED strips + 2 x MeanWell HLG-320H-48A each driving 5 x same LED strips. Strips are mounted on ALU profiles (heatsinks) warming up to 58 – 60 C.
• Method: SCROG
• Strain: Dinafems’ Moby Dick (8 + 4 plants). 4 plants are under additional 6,6x4 (200x120 cm) screen.
• Medium: Soil (Plagron) in ~13,2 gal (50L) AIR pots.
• Feeding/nutrients: Canna Terra (Vega, Flores, Rhizotonic, Cannazym, PK13/14)
• Grow cycle: From clones to 75% filled screen 18h MH cycle for about 1,5 month and almost 3 weeks into flowering I got first signs of buds.
• Performance: /

So, main three changes are the lighting, removal of grow tent and pots. There were previous attempts to expend operation by setup additional screen and putting lights on light movers, but that setup just didn’t give enough light and performance was poor (even less than in tent, about 0,8 g/W). Everything else was the same.

What is the problem now? Veg took twice the time it took under HIDs, but OK, these LEDs are 3000K so I was expecting slower growth. However, the main problem is that even 3 weeks into flowering I don’t see any real budding. With HIDs it usually took just a couple of days for first pistils to appear, now 3 weeks into flowering only few can be seen... :( Otherwise, plants are looking very healthy, no visible problems etc.

I attached few pics for better understanding.

Can someone please explain what am I missing, doing wrong, should be doing differently and most importantly should I keep my optimism or expect failure?

tl;rd: Switched from HID to LEDs, rate of growth and flowering are very slow and in general just underperforming.

 

[Kepp89]

have you peeked into the room at lights off to make sure none of the LED dots are holding energy/theres no status LED light anywhere on the light frame(s)? granted i only have 1 plant, i have no problems with my single 400watt full spectrum simple led light. it took i think 9 or 10 days before i saw tiny little buds forming.

 

[JWM2]

What’s your VPD? Due to lack of UV you also need to run higher room temps. In the mid 80s with a decent VPD.

 

[Baudelaire]

You need more light. Like, twice as much light. PPFD in particular.

I don't know what your PPFD (photosynthetic intensity) is, but I've done extensive PAR testing on Samsung LED-based lighting racks like yours. And, as a rule of thumb, until you are breaking 30 watts/sf, you ain't playing ball. 35-40 w/sf is ideal. That's about 4000 watts over your 116 sf canopy. You've got about 15 w/sf, maybe 18 w/sf with your drivers running on full overdrive (those Mean Well A-style drivers usually have about 15% overdrive capacity over their OEM rating.) Your current light intensity is barely enough for a veg space.

The good news is you've got a great start with good quality LED strips and a good solid design. Now add another set of strips in-between the ones you've already mounted. Split the circuit into two so you can add additional drivers.

I recommend getting a cheap lux meter at least, a PAR meter is even better. But the cheapo $20 Ebay meters are helpful as well in determining relative light intensity. There's even a couple of free/cheap phone-based lux meter apps. Shoot for 25,000 lux at a bare minimum at all points across your canopy. 35-50K lux is much better. Using a basic PAR meter like the $100 Hydrofarm, aim for 600+ PPFD across the canopy.

In the meantime, if you are in the middle of cycle and need light now, center one your two 600 w HPS over each of your canopies, above the racks. You might love the results.

Peace -b420

 

[Ritualis]

What’s your VPD? Due to lack of UV you also need to run higher room temps. In the mid 80s with a decent VPD.

Hi,

OP here. Don't know if anyone will see this, but it was temperature all along! Fixed that and had a pretty good round. The following (summer) round now, was exceptional to say the least! Thanks again, wish you all good growths.

 

[Mr.jiujitsu]

You need more light. Like, twice as much light. PPFD in particular.

I don't know what your PPFD (photosynthetic intensity) is, but I've done extensive PAR testing on Samsung LED-based lighting racks like yours. And, as a rule of thumb, until you are breaking 30 watts/sf, you ain't playing ball. 35-40 w/sf is ideal. That's about 4000 watts over your 116 sf canopy. You've got about 15 w/sf, maybe 18 w/sf with your drivers running on full overdrive (those Mean Well A-style drivers usually have about 15% overdrive capacity over their OEM rating.) Your current light intensity is barely enough for a veg space.

The good news is you've got a great start with good quality LED strips and a good solid design. Now add another set of strips in-between the ones you've already mounted. Split the circuit into two so you can add additional drivers.

I recommend getting a cheap lux meter at least, a PAR meter is even better. But the cheapo $20 Ebay meters are helpful as well in determining relative light intensity. There's even a couple of free/cheap phone-based lux meter apps. Shoot for 25,000 lux at a bare minimum at all points across your canopy. 35-50K lux is much better. Using a basic PAR meter like the $100 Hydrofarm, aim for 600+ PPFD across the canopy.

In the meantime, if you are in the middle of cycle and need light now, center one your two 600 w HPS over each of your canopies, above the racks. You might love the results.

Peace -b420

This