What’s the best Micro powder to add for the roots

"Mykos" from Xtreme Gardening works well. However, most products need to be placed in the planting hole at transplant time so that it contacts the roots. Amino acids, aloe extract, humic acid, fulvic acid and kelp products can be watered in though....all these boost plant vigor. Go easy on small plants, they are still very fragile and do not like heavy doses of anything.....many weak doses are better than heavy doses infrequently.

Coconut water and aloe will also make them thrives at this stage as bio stimulants. Something to do with all the enzymes and the trace minerals. There are many properties they have I still don't fully understand. I buy the cheapest one, Mycho's seems to work good. Down to earth has a product called soluble root zone that has a plethora of beneficial fungi and bacteria i been using seems to make my plants happy. Just don't overdo anything at this stage that's going to help them thrive more than anything.

Just don't overpay. It's not magic and it's not a super profound effect. There are different metrics used. Some are more correlative than others. spore count vs propagules ... spore count is probably a better measure. Then, there is the "endo" and "ecto" types.. one is more likely to be helpful to woody plants.. i've forgotten which it is, but a simple google search will fill in the blank. I believe oyu want the endo. I am in soilless, so myco is 100% useless for me. Context matters. This is no gauranteed positive effect with limited evidence, but it's definitely useless for soilless/hydro contexts where nutrition is 100% plant available and in proper proportions around roots without any help from fungi. You can 'grow your own' so to speak too. again, google can help with that.

Planet success - great white is top top for me, but i started to add ecothrive - biosys in the mix too, for best grow rate i could extract ...

I've had good experiences with Dynomyco Spark. It's easy to incorporate while watering and doesn't need to be mixed into the soil separately.