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First time grow?
00110001001001111Oanswered grow question 1mo ago
trial and errorr.
16-20" is usually a good range...when other factors jive well together, hanging distance is best choosen by resulting area of coverage -- how much difference is the central readigns from the readings along the edges - a simple klux app can do this, or you can use an app that converts it to ppf/ppe, but for this endeavour there is no benefit and there is a +/-10% error on that conversion due to variances in LED grow lights.
any light measurement can give you proportional intensity differences from center to edges.. is it 50% of the central reading? is it 66%? are you sacrificing overall average to even out the light?
Their "PAR" maps can help choose hanging distance too.
umol/s of PAR and hours of operation are proportional to resulting DLI. DLI is what matters. "35" DLI is 35 dli regardless of how big the garden is or how many hours the lights operate. Learn about Daily Light Integral and avoid a tone of bad advice, lol. Many people look at one factor without considering the other. This is like miles per hour without duration of travel time.. the distance traveled being an analog to DLI. Rate x time = something useful. One alone is mostly useless.
These are just good starting points. No matter what, your local climate will cause variance. You will always need to observe and react to the plant for fine-tuning adjustments. The developing distance between growth nodes is your guide to adjust the light. Too tight = need less light. Too lanky = need more light. That's how you find "Your" goldielocks zone.
if not intimidated my math, read the DLI wiki page. Check out your umol/s production of the light, assume it's focused on the proper area (hanging distance) and shoot for 35-40 DLI to start. The percent dim should nearly 1:1 correlate with umol/s output.
FC4000
of course mars is now limiting useful information. they don't give umol/s tech details or diode count to verify if they are lying about efficacy... Let's assume they are not lying.
2.85 * 320 watts = 912 umol/s PAR output from the diode.
8ft^2 / 10.764 m^2 = .74 m^2 coverage
912 / .74 = about 1200 PPFD maximum in 8sq ft tent -- actual is less than this due to missing plant or absorbed into walls. That's baked into the suggestion already given typical hanging distances.
This is a shit ton at 100% for 8sq ft (about 52 DLI). Refer to any DLI table to shoot for 35-40 DLI
12h @ 900 ppfd = 38.9 DLI
900 /1200 = 75% -- with ambient co2 conditions, 75% in a 4x2 over 12 hours is as much as you need.
18 hours @ 675 PPFD = 38.9 DLI (1:1 inversely proportional to hours of operation)
600/1200 = 50% -- with ambient co2 conditions, 50% in a 4x2 over 18 hours is as much as you need.
These are starting points... May need slight adjustmennt from there.
Also, unlike their suggestion of 12", i'd go to 15-16" hanging distance, minimum. If you have a poor climate, you may want it even higher or slightly more dimmed. The plant growth will scream it at you eventually.
for 12 hour operation and ambient co2, the max coverage of this light is closer to 11 sq ft as opposed to 8 sq ft. This might be better in a 3x4 space and some room leftover for equipment or avoid contact with walls.
heh, usually mars has better starting suggestions. Their suggestion seems to be based upon 1200-1300ppm of CO2 and not ambient co2. plus, an improper vpd (temp and rh) will result in less potential photosynthesis per day (i.e. lower DLI maximum before damaging/stunting). If you were supplementing CO2 it's well-tailored for a 4x2 area.
more is not better. the right amount is better.
yan402answered grow question 1mo ago
PS: That FC4000 EVO throws serious photons even at 40%. It’s not a weak light, it’s just easy to overdo it if the room’s not balanced yet. You’re doing it right keeping it low until she’s ready.
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yan402answered grow question 1mo ago
Hey growmie, week 6 veg and 40% at 20” is actually a nice cautious setup. Mars claims are always a bit aggressive, 12–18” at 75% might work later, but not this early unless you’ve got perfect temps and airflow dialed.
Right now, I’d bump up to 55–60% and keep the same distance. Watch how the plant reacts for 2–3 days. If no signs of bleaching or clawing, go a bit higher from there. Slow ramp = no shock.
Your diary looks solid so far, plant looks happy,no rush. Also, if it “cooked” last time at 75%, that tells you your room probably needs better temp control or more airflow before pushing that high again. Light wasn’t the only issue.
You’re right to trust your gut over manufacturer numbers. They don’t grow in tents, we do.
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TruTraTrianswered grow question 1mo ago
At week 6, 40% @ 20" is quite low—you can definitely start increasing power now. Try bumping to 50–60% while keeping the distance the same. Watch how the plants respond over 2–3 days.
Mars Hydro’s 75% at 12–18" is too much for seedlings, but by mid-veg or early flower, it’s where you should be heading. Slowly raise output or lower the light distance (but not both at once).
Gradual ramp-up avoids light shock—and you’re in the perfect window to do it now.
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Ninjabudsanswered grow question 1mo ago
Okay, here's the thing about grow lights and weed plants. You want them close enough to get plenty of light, but not so close that they get burned. A good rule of thumb is to start with the light about 12 to 18 inches away from the top of the plant. Then, you can adjust it from there based on how the plant seems to be doing.
If the leaves start to look pale or yellow, that could be a sign that the light's too close. You want to see nice, healthy green leaves. Also, keep in mind that different types of grow lights put out different amounts of heat, so you might need to adjust the distance depending on what kind you're using.
PAR meters are a great tool for measuring the amount of light your plants are getting. They measure the photosynthetically active radiation, which is the light that plants use for photosynthesis. This can help you figure out the best distance to keep your grow lights from your plants.
The best light spectrums for growing weed are usually in the red and blue ranges. Red light is important for flowering, while blue light is important for vegetative growth. You can find grow lights that offer a full spectrum of light, or you can use separate lights for each stage of growth.
Also always make sure lighting was the problem and. It something else
Healthy leaves on a weed plant should be a vibrant green color and stand upright. If the leaves are drooping, curling, or turning yellow, it could be a sign of a problem. Some common issues include nutrient deficiencies, overwatering, underwatering, or pests.
Healthy roots on a weed plant should be white or cream-colored and have a strong, fibrous structure. If the roots are brown, slimy, or have a foul odor, it could be a sign of root rot. Root rot is a serious problem that can kill your plant, so it's important to address it quickly.
Your weed plant will tell you if it's getting too much or too little light through its leaves. If the leaves start to turn yellow or brown, or if they look burned, that's a sign of too much light. On the other hand, if the leaves are pale or stretched out, it might not be getting enough light. You'll want to adjust your grow lights accordingly to keep your plant happy and healthy.
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Ninjabudsanswered grow question 1mo ago
The only way to know for sure what your dealing with is a par meter that reads umol’s don’t get a lucky meter even though there cheep they don’t work and they are not comparable
If you can’t afford one then watch what the plants tell you start the light low and slowly increase lighting amount over time never make fast lighting adjist
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AestheticGeneticsanswered grow question 1mo ago
You can also message me with anyother questions for more detailed responses since i cant ask questions this way to get a better idea of what youre working with. Best of luck!
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AestheticGeneticsanswered grow question 1mo ago
Need a little more information to be more helpful. But my advice is to read your plants, if theyre happy then just let them be.
If you want to get more technical. Download the photone app on your phone and you can figure out what the ppfd is at for your plants with whatever distance and whatever power you have your light at.
I dont start increasing light intensity until the begining of flower and then around week 5 of flower, i try to increase my light up as much as possible, so long as temps allow me to do so.
If your plants got cooked, it could have to do with temperature and humidity levels along with other environmental things like airflow and vpd.
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