Fist timer | Grow detail and issues

[alfaceroxa]

Hello, first time grower here! I wanted to ask you for some guidance.

I build a cabinet grow:


It has:

• Circulating fan
• Dehumidifier (keeps it between 60 - 75%)
• Temperature around 30ºc (86ºf)
• Humidity and Temp sensor
• Raspberry Pi to keep light cycle (18/6h) and dehumidifier

For lights I am using

• 4x (real 10w) Full Spectrum LED Lamp
• 1x (real 40w) Full Spectrum LED Lamp
• 8x full spectrum led strips

All the lights combined draw around 80w (I have a meter)

Top of plant stays around 30cm (12in) from lamps.

Soil

• 1 part of vermiculite
• 2 parts of perlite
• 3 parts of soil

The plant now has ~16cm (6in), it took around 60 days to reach this size, I believe it was lack of light, on the first 50 days I only had 2x of the small led lamps, then I decided to add all the rest (not sure if the leds strips help, by anyway).

I water it in a 5 days interval, with only water. At day 45 I started to add fertilizar

• Day 45 watered with BioBuzz BioGrow
  • I noticed small discoloration around the tip of one leaf, and tip pointing down
• Day 50 plain water
• Day 55 fertilizer
  • No sign of discoloration
• Day 60 I only water
  • I do see a lot of discoloration (you can see in the previous picture too)

What could be happening?

• Could this be overfert?
  • Shouldn’t it manifest around day 55 when I watered it with fertilizer?
  • Looks more like it: How to Fix Cannabis Nutrient Burn - Pics & Symptoms
  • But at the same time, it is not only the tips…
• Could this be too close to light source?
  • Also looks like it: Cannabis Light Burn & Light Bleaching Symptoms & Solutions!
  • But if it was light burn, should not it manifest first on the top leaves?
  • Should I lower it to ground level?
• Could this be high temperature (30c / 86f)?
  • Does not look like it, leaves are not curving: How to Prevent & Treat Heat Stressed Cannabis Plants
• Could this be potassium deficiency
  • Also looks a little bit like it: How to fix Cannabis Potassium Deficiency (K) Pics & Symptoms

Thank you very much in advance!

[dilvish]

First problem is I see no indication that you tested the water and or water/nutrient mix for PH. Second is that temp and humidity are too high IMHO. 27C is optimal and around 50-60% humidity, if the gauges are accurate...but you use the term "around" so are you checking the gauge or not?
Then there is the light issue. your total combined lights are 80W and that's really not enough light even for one plant. I also doubt those lights are truly full spectrum...the ones on top maybe but definitely not the strips.

Cannabis needs a lot of full spectrum light...more so than many plants and are very sensitive to alkaline/acidity of the soil.

Get a pot, throw in some soil, add some lights and some water and you can certainly grow a cannabis plant. if you don't take proper steps to ensure the growing conditions are ideal, it won't produce buds/flower. When I first started that's exactly what I did...I grew 4 plants and in total got less than 28 grams(an ounce) and they took forever. I was lucky to even get that amount and it wasn't potent (Little Miss) at all.

The intent is to get the plant to grow big fat sticky buds. That is the most potent part of the plant. If you like just smoking fan leaves then you get virtually no "high" as the leaves contain only traces of THC.

After 60 days this plant looks stringy and will likely produce little or no buds. The cause is probably too much heat/humidity and not nearly enough full spectrum light. Think of light as plant food and nutrients as vitamins. Think of the leaves as solar panels and the more they collect the more food to the plant. Not adding nutrients until day 45 was also a mistake assuming the soil was just regular soil and not some type of supersoil. Even super soil starts to use up all it's nutrients after about 3-4 weeks. Nitrogen is very important in the vegetative stage as that is when the plant uses the most. Did you even give the correct amount of BioBizz? if you weren't using supersoil then when the first set of leaves developed you should have started adding nutrients.

[alfaceroxa]

Hey, thank you for the answer! It is really helping me.

About temp: I will add an exhaust fan to keep it cooler, at my home the temp is 27c and we are in spring time, so that is going to be a challenge anyway. Ah I also say "around" because it fluctuates some degrees during the day.

About the lights, I had only 2 of the small led lights, when I added the rest the plant started growing faster, so definitely light can be improved. Also planning on ditch the led strips, they surely are serving only for aesthetics.

Water: I measure the water PH and it sits around 6.5, that is after I add fertilizer to it. I am using 1ml of fertilizer to 1l of water (manufacturer recommendation).

But fertilization is a difficult topic for me. I was afraid of adding fertilizer after the plant developed it first pair of adult leaves (as I read on the books), the plant was so tiny (5cm or so). And I was afraid it was going to die of overfert. I added fertilizer when the plant had 9cm and 7 pairs of adult leafs. But right after I added it, the points wend yellow and that scared the s#it out of me.

My soil is not super soil, is a regular soil.

Should I water it with fertilizer right after it develops the first pair of mature leaves?
Should I always add fertilizer to the water?
Should not I be worried about that brow tips?

Thank you.

[SoOrbudgal]

Are you in a area where it can grow outdoors? Boy i'd stick it under a larger LED perhaps the sun will help you more. Those lights i just don't think they will give you much if any bud growth. Yes fertilize she needs food. Don't go overboard with the first food, do 1/2 amount.

[dilvish]

plants in seedling and vegetative stage require regular feedings, especially in soil that is just plain. Once a plant gets its first set of leaves it should have nutrients / fertilizer. Just don't get any on the leaves. In soil or coir it's a good practice to flush with plain water every other watering so that there is no build up of fertilizer. Make sure the pots always have good drainage otherwise the roots end up sitting in water and will rot.

Do some more reading and you'll get the hang of it.

[alfaceroxa]

Hey, quick update.
The new light really made a difference. She growed a bigger big and some small popcorns.



Next time I will try feeding it earlier, move the lights closer and do some LST to get more than one big cola.
I can see trychromes with a magnifier.


I also see this problem, which I assume is Potassium Deficiency which could make sense since I started feeding it too late.


Will keep a few more days untill most trychomes are amber to harvest it. Later on I share the results. Thank you for the great insights!