How much artificial light should an avocado tree get?

Question

I got 2 "young" grafted avocado trees 2-3 weeks ago. I have them indoors. From May I'd say, until September, the room gets some hours of sunlight but unfortunately when I got them it was the last week where the sun got. So I decided to get an artificial light: Niello LED GrowLight, 1200w with UV & IR. Specs: White, Blue, Red, IR y UV (3000K, 5000K, 660nm, IR 760nm and UV 395nm). Efficiency: 2.7 μmol/J

The avocadoes did not react too much with the light. I transplanted them as advised from the seller (they came in the classic long cilinder avocado pots, the transplant was clean and the roots were (I'd say) mostly untouched! So transplant shock must be minimal, but it will take some time.

I have been reading several sites: getUrbanLeaf avocado was the most insightful in "technical details" of avocado trees and lightning, but at the same time, it's the first site I see that recommends such little light hours:

Avocado plants need the equivalent of 6+ hours of direct sunlight [DLI of 18+ mol/m²/day] to grow their best. In order to provide an equivalent amount for your avocado with a plant light, it needs to be pretty bright! The 24W Sansi bulb should be placed 6 inches away from the top of the plant. This will give your PPFD (the standard measure of brightness) of 500 μmol/m²/s.

There is a picture with the PPFD for my lights, but I still do not really understand how to make the "conversion" And also:

Avocado plants are known as “short-day,” meaning they’ll develop faster if they sense over 12 hours of darkness. We want them to progress into flowering as soon as possible, so we recommend setting up a timer to leave it on for only 10 hours per day.

With this, I guess it means that after 10h, it's better if the room is kind of dark. Other sites like The Spruce - Avocadoes indoors, Home for the harvest - avocadoes indoors, planet natural blog - about light bulbs, garden.org - using led to grow avos, and finally: south west journal.

I see that 10h should be the max according to all sites, average stating: 6-8. I have been using 11h average of light at intensity 70-80 average. I can try and use 9-10h instead. But at what insensity should I input, having these technical details? I still am a bit confused, because my lamp suggests 16h for flowering at the strongest capacity of 100% light, and for growing, 14h at 60. Is there any way to combine this? For example: 8h at 100% is equivalent to 10-11h at 70%?

The leaves seem to be curling and to me it definitely does not seem like burning, but it might be too much light? Definitely not overwatered, might be some transplant shock.

And the curliness of the leaves in the following pictures. Some have random holes, some seem "bitten" but I am sure there are no insects... Some seem like transplat shocked/not enough water, but soil is moist (not even wet).

1 week UPDATE: The state of the trees is the same, except for the falling of some leaves in both (more in the hass one). Im making sure the soil is never wet, just moist. At the moment my guess is that it will lose all or most leaves and in a month, new leaves will appear. This is my guess because it is what has happened to me before

Answer 1

They way the leaves are curling under themselves i would say that the trees are getting too much intense light after transplant and can’t uptake enough water to compensate for the moisture lost from being under such an intense light. Try reducing the intensity to at or below 50% and once you think they have become established then slowly increase the lights intensity by 5 % every couple weeks. Avocados are native to regions around the equator and as such should be in a 12/12 light cycle with moderately high light intensity but young avocados don’t have a strong enough root system to deal with a harsh growing environment. Until it becomes established or until the root system matures enough to uptake enough water then I would avoid keeping it under a strong light. Also tropical trees like avocados and mango need to go threw a period of drought to push out flowers and set fruit so make sure that you keep the soil moist until they are mature enough to support fruit sets and won’t die from not having enough energy stored. You have the right idea on diagnosing your trees troubles,I know I should avoid personal experience but haveing grown many avo trees successfully only to have them killed by cats using them as toilets, my experience is that generally trees will take care of themselves and most of the time even looking at them for too long will make them uncomfortable,if you do end up reducing the intensity and notice no new growth after a couple of weeks then the intensity is too low or it not a long enough day cycle, I give my avocado trees a good 6 hours of direct sunlight and the other six hours of the day cycle as bright indirect light and they seem to do just fine, I also give them used coffee grounds as fertilizer every month for the three macro nutrients it needs as well as the micros like calcium and magnesium, another thing to mention is that many avocado tree will become deficient in other micro nutrients like zinc, iron, copper, boron and molybdenum which is also found in coffee grounds in trace quantities.