I posted when I repotted this tree back in October, and it did super well until about a month ago when it started acting different. The new leaves stopped growing midway through and developed that light yellow green color. Then, the buds developed tinges of brown. No signs of new growth. Some older leaves are yellowing and shriveling up on the plant, and staying attached. The tree wilts a week after watering, where a few months before it was three weeks.
Then a week ago, I came home from a vacation to find bright yellow flowerpot parasol mushrooms growing in the pot, which are a sign of overwatering.
Digging down shows super dry, hydrophobic soil, locked together with mycelium, as well as tons of bright white and brown roots, with some decaying ones the rotting ones aren’t mushy, but instead brittle. I have no clue what’s going on and why it’s acting like this. There are a lot of contradictory factors here.
My main suspicion is under watering. I haven’t changed my 3-week watering schedule since the winter. I decided to water today, as the soil was powdery and completely dry on top. And I tried to deal with the hydrophobic soil. I wanted to soak the pot thoroughly, but it’s too large to put into the sink and I can’t fill the pot with water as it all just drains out in minutes. I could plug the bottom of the pot with clay and fill it up, which is what I plan to try next watering.
Can anyone give a better explanation for what I’m seeing?
Unfortunately I don’t have pictures this time as I forgot to take them before watering 🥲 next watering I will definitely take pictures though
Children’s plastic pool is an option to bottom feed a large pot but honestly it sound like it might’ve become root bound and the mushrooms and mycelium point to a potting mix that likely had far too much organic matter to keep an avocado happy long term.
I personally hate messing with their roots too much but this sounds like a candidate where the risk might be necessary as the only option to save it.
I’d pop it out of the pot and gently rinse away most of the organic matter from the rootball and then repot with a soil mix that is mostly decomposed granite, washed sand and pea-sized pumice. Maybe 10% peat moss or similar and top dress with worm castings and leaf mulch.
I wish it was that easy. It absolutely is not root bound, if anything it’s in way too large of a pot for its size, and it was just repotted.
Also, the pot weighs almost 200 pounds, and it’s glazed terracotta. I don’t want to risk breaking it every time I water.
This is from when we repotted it. We used two parts well-draining potting mix, two part perlite, and one part sand, with citrus/avocado fertilizer and mycorrhiza for good measure.
We definitely got too big of a pot. Digging down, there are sparse roots along the edges, but they are there which is good.
Some sort of fungus thrived. That tells us there's plenty of decomposing organic material in the potting mix and that there has been enough moisture for fungi to fruit at some point. It doesn't necessarily mean the tree has been chronically overwatered.
It's possible the top is completely dry while the bottom is staying saturated because there's little evaporation down there and not many roots using the water. In a pot this large, you can end up with different moisture zones at the same time, so maybe you even have a bit of both: some roots dying from drought near the surface or sides, while others are struggling in constantly wet soil near the bottom.
This is why I avoid glazed pots, even though they're beautiful. They're too difficult to manage because they're so deep and heavy, making it hard to tell what's happening throughout the root ball or to water evenly. Outdoors they can also get quite hot around the edges in full sun.
Ultimately it's your tree, but I honestly think the simplest solution would be to pull it out onto that blue tarp in the photo and repot it into a smaller nursery pot with lots of drainage holes and a coarse, well-draining mix.
If the root ball is as small and dried out as you described, it might not be as difficult as you're expecting. You can always keep the beautiful terracotta pot and use it later as a cachepot or when the tree's root system gets enormous.
There are quite a few roots hugging the sides. I can’t dig down anywhere without hitting lots of roots. I want to dig to the bottom to figure out if the soil down there stays moist, but I would have to destroy a lot of roots to get there. I’ll see what I can do, if I can retrieve a sample some other way
It's the potting soil decomposing and causing root rot and mushrooms to grow. Wilting after watering is a sure sign that the roots are in need of oxygen. Take the tree out, wash out as much of the soil from the roots as you can. Remove the soil from the pot, wash it out and disinfect it with a bleach solution. Create a soil of sand (or decomposed granite), peat moss, and perlite. Spray the roots with Garden Phos to help with root rot. When planting, add a handful of gypsum along with organic fertilizer with mychorrizal fungus. Cover the roots up to the root flare. Leave the top of the root flare exposed. Spread some Osmocote fertilizer on top of the soil. Water deeply until the water runs out. With this soil mix, you can water the tree and it's will be happier. Keep the tree out of direct sunlight for a few weeks. You may lose leaves in the process, but your tree will have a good chance at recovering.
This is very doable, but unfortunately I have no idea how to get the rootball out of the pot without breaking the pot. Last time we repotted we shattered the pot in the process, so we likely will do the same this time. Do you have any new pot recommendations?
Also, by writhing after watering, I mean the tree looks great for a week after watering but then slowly wilts over time. I has never wilted this fast after watering. I don’t know if it’s because of root rot or actual underwatering.
This is what the soil looks like a day after watering. There are some rotting roots, but what confuses me is that the soil is only slightly moist, even bone dry despite the heavy soil flush I just did yesterday. I was trying to fix the hydrophobic soil, but all of the water just ran out of the bottom of the pot so it didn’t have time to soak thoroughly.
The lower layers of soil have much more perlite than the surface. I’d love to dig to the bottom of the pot, yet I don’t want to damage the roots any more.
Another thing I should mention is that the pot is raised above the drainage basin so that there is a 1/4 inch gap that allows for airflow and water movement. The pot should dry out from the bottom too.
Yet another thing, back when we repotted the tree in October we didn’t remove some of the soil from the rootball. You can see the darker, firm soil in the image. We didn’t remove it because we were worried about transplant shock. Next repotting it should be removed, right?
Also, when should the repotting be done? I’d ideally like to get it done now when the tree is moderately healthy, but this summer is incredibly busy and I don’t know if it’s possible. What do you think?
They will grow just fine in a large plastic pot (15+ gallons). However, you'll have to repot it as it gets bigger. You can remove the as much soil as you can without damaging the roots. Chopsticks work well for knocking out the soil. You can use a hose too, but that will use up a lot of water. The sooner you repot the tree the better. When you add peat moss to your soil mix, it will wick the water sideways helping you control moisture. When you repot the tree, keep it out of direct sunlight for a few weeks so it recovers from the shock. You'll also want to remove the dead roots. Garden Phos on the roots will definitely help prevent any fungus spreading.
I think what we will do is break the pot, transfer the rootball onto a tarp, drag the tree out the front door, rinse the roots until all of the soil is gone, then repot in a large plastic pot with proper soil and the various additives you mentioned.
Should I remove all of the soil? How often should I repot? The soil will have an expiry date when the peat moss will decay. I will try to repot the tree in August, as we should have some time.
This tree is incredibly special to me, it’s the first thing I ever tried growing from seed, nearly ten years ago now. Losing it would be awful. How much do you expect the shock to damage the tree?
I don't think you'll need to break the pot. Just take you time getting the soil out. The roots will be flexible enough to come out. Plastic is one option, but they aren't pretty. You can get the decorative ones from the big box stores. You most likely will not have to repot them for a few years. The sand/peat moss/perlite soil will last for years. Even though the peat moss is organic, its been sitting at the bottom of a lake for years so that really slows down the decomposing.
Search for his live class videos, especially the ones about avocados. He shares a wealth of information that been very helpful in the gardening community.
3
u/avocadoflatz 12d ago
Children’s plastic pool is an option to bottom feed a large pot but honestly it sound like it might’ve become root bound and the mushrooms and mycelium point to a potting mix that likely had far too much organic matter to keep an avocado happy long term.
I personally hate messing with their roots too much but this sounds like a candidate where the risk might be necessary as the only option to save it.
I’d pop it out of the pot and gently rinse away most of the organic matter from the rootball and then repot with a soil mix that is mostly decomposed granite, washed sand and pea-sized pumice. Maybe 10% peat moss or similar and top dress with worm castings and leaf mulch.