I've had some terrible luck with attempting to grow Avacado trees in pots, and killing grafted trees is getting to be an expensive and unsatisfying hobby! I'm hoping some experts with experience can take a look and comment or make suggestions. I have some suspicion that both of my trees have root rot, when I dug up and inspected some of the roots about an inch deep, some were healthy and some were dead or dark brown, but I don't want to mess with the soil too much to get a better look. I'm hoping that some of the roots died during the transplant and then less than ideal conditions in a dry garage under a grow light over the winter (I'd bring them inside if the temp in the garage got below 45) and it isn't phytophthora.

I potting mix I used is:

5 Parts Pumice

1 Part Pearlite

6.5 Parts Coir

2 Parts orchid mix

3 Parts Potting Soil

I recently mixed half a cup of iron chelate, half a cup of gypsum salt, and some leaf compost as a layer to the top inch of topsoil.

I'm using canvas pots sitting on a saucer full of rocks that drains onto the deck, and typically water every 5 days depending on rain and temperatures. I figured the canvas pots would be good for a plant that likes dry roots, and as a bonus they're very light so it's easier to move them inside if needed.

The one above is a Mexicola variety. My main concern are those leaves in the middle of the picture. They're relatively young, about 3 or 4 months old, but never fully grew, came out yellow, and are covered with brown spots. Everything above those leaves has grown in the past 2 months or so, and it looks a lot healthier, but they seem very pale compared to healthy Avacado leaves.

This one is my Hass variety. I received it as a replacement in the fall and it stayed in my garage under a grow light since I received it, so it never really had a period of great growing conditions. The few branches it had when I received it from the nursery died back immediately after transplant, but the stem had a dozen leaves that were fine until they all fell off as this new growth started to emerge in the past month. It seemed to have very few roots in the top 2 inches of the soil compared to the Mexicola, but I have some hope because I've read that top growth is limited when a tree is suffering from root rot, and the top of this tree is exploding.

This is what it looked like less than a month ago:

One of my concerns is that some of the new leaves look a bit deformed near the tips... Is that normal? The new leaves on the Mexicola tree do not have anything similar.

Any general advice would be appreciated.

I'm also be curious if there's a definitive way to check for root rot without being too invasive, as I'd prefer saving my efforts and pull the plug if they're going to be short lived.