Constant fear of overwatering

[simoncools]

I have been doing bonsai for a little over a year now and I started out with mostly cheaper trees.
I purposely waited on getting more costly trees to make sure I wasnt going to let them die on me.
So far, none of my bonsai have died (knock on wood). However i did have a garden center japanese maple that i chopped down and put in a way oversized pot in purely organic soil. Low and behold, it died after about half a year.

Since then, i've been constantly stressing out over over- and underwatering my trees.
I usually always water in the evening after sunset and on very hot summer days, i'll water in the morning and afternoon.

Currently the water is extremely unstable where I live, and it is really hard to predict whether I should water or not.
It could be grey weather and raining in the morning and suddenly full sun for the rest of the day.
Because of this, I tend to stay on the safe side and water my trees as soon as the top starts to dry out a bit.

This leaves me worried that i might be overwatering my trees. But on the other hand im afraid that if i dont water them and come home in the evening, i'll find my trees dried out.


My question is, how likely is it for overwatering to do any real damage to bonsai that are in well-draining (mostly) organic soil, especially compared to the risk of a tree drying out during the day.

I've always told myself that watering too often is probably better than not watering often enough, but is that really the case?

 

[darzuo]

In my experience, it takes quite a bit to over-water trees in a well-draining mix as long as you're sensible about it. Root rot is certainly an issue to be mindful of, but it's much more of an issue in organic soils that hold a ton of water. I've had trees out in the rain for upwards of a week with no issues, and if you think about large outdoor operations, they're not likely doing anything special to shelter trees from rain when it comes down for several days straight. Maybe others experiences are different and it varies by climate and trees, but I've never run into problems with proper bonsai soil as long as it doesn't go too long without drying a bit.

 

[BrightsideB]

Overwatering refers to watering to the detriment to its health. If you water three times a day and the tree needs that to be healthy due media, heat, etc. factors. That’s no really overwatering. It’s watering your tree properly. There is also a gas exchange that takes place when watering and in a mix that drains well. The water flowing through and around all the particles pulls oxygen back into the soil. Harder for anaerobic bacteria to grow. I use pumice in any mix I use whether for trees in ceramic pots or ones in larger to grow out. There are different kinds. You may find one to be more ideal for you.

 

[Jrmcmich]

In future you could change soil to more inorganic soil (APL) or similar combo and use a wooden chop stick in mean time to check soil moisture. I have found it virtually impossible to overwater a tree especially when in pure pumice which I have couple collected and a zelkova in a box pure pumice. Many of mine in 80/20 perlite/coco coir amd those I check daily before watering and sometimes amazed even when 90 out might be every other day for some trees yet others more thirsty and are daily. A couple (2) twice a day.

 

[Eckhoffw]

Like @BrightsideB and @Jrmcmich have noted, an inorganic mix (I’ll ad, of approximately 1/4” particles) will pretty much eliminate the possibility of overwatering.

However, you will need to water every, or every other day unless the species prefers dryer conditions. Even my succulents ( growing in inorganic soil get water once or twice a week during the growing season.

 

[Glaucus]

Overwatering doesn't really happen to healthy trees in proper pots with good root systems in summer.

The main difference between symptoms of overwatering vs underwatering is that overwatering is chronic and underwatering is acute.

 

[pandacular]

Hey Simon, welcome to the forum! I just got back from a visit to your lovely country, and it seems like an awesome place to do bonsai. I even got to visit the garden of Danny Use in Laarne, which I highly recommend.

Watering is tough. It's the last thing an apprentice is allowed to do in Japan, and even then they will not get it right immediately. Every professional I know of emphasizes the key to getting timing of watering really dialed. But the trees they are talking about are extremely refined and likely very old plants. It's true that it's important to the health of the plants, but it's far more important to older, more established trees.

It's not clear from your post, but do you "broadcast water", in other words, water all your plants at every watering? Or do you inspect each individual plant for its water needs? It is recommended to do the latter, and often check your collection multiple times per day when the days are long.

Since then, i've been constantly stressing out over over- and underwatering my trees.

This is pretty normal. It's the hardest part of the whole practice and lifestyle.

I usually always water in the evening after sunset and on very hot summer days, i'll water in the morning and afternoon.

Probably best to water in the morning as a routine if possible. Watering after sunset can cause issues of fungus and other nasties. A tree doesn't generally draw much water after dark

Because of this, I tend to stay on the safe side and water my trees as soon as the top starts to dry out a bit.

This leaves me worried that i might be overwatering my trees. But on the other hand im afraid that if i dont water them and come home in the evening, i'll find my trees dried out.
...

I've always told myself that watering too often is probably better than not watering often enough, but is that really the case?

This again is natural. There's a degree of truth that it's better to play it safe, but if it's too "safe" that your trees never thrive, it's not really safe at all. Glaucus hits on this very well; acute v chronic.

I do believe that I see many more beginner trees that show signs of over watering than of underwatering. Maybe that's because the latter are dead, but I think overwatering is probably a bigger challenge in the community than underwatering. I think most people start out underestimating how dry a tree should get between waterings, particularly for pines and other dry conifers, or even maples.

I don't say this to discourage, in fact the opposite! All the things you're worried about are likely important and worrying about them is the first step to overcoming the challenges and achieving your goals.

 

[Shibui]

Underwatering will kill a tree in just a few hours. It takes months of overwatering to cause root rot and kill the tree. I prefer to err on the overwatering side rather than too little. Plenty of water at every watering is important. Water should run through the soil and out the bottom of the pot. Water draining through the soil takes away fertiliser residue and also draws fresh air into the soil. If you are not using enough water to drain through the soil you'll often end up with other chronic problems.

As already mentioned, you cannot overwater a tree on one day. Overwatering is chronic, meaning it takes a long time. The roots need to be in soggy soil for many weeks.
Most of my nursery is watered by automatic watering system so all trees get morning and night water. If I'm away and we have a cloudy day or if it rains for a couple of days that's no harm, even though the trees will also get watered twice a day. The soil will dry out on the next sunny day so no problem.
I also use a mostly organic soil mix.

 

[simoncools]

Hey Simon, welcome to the forum! I just got back from a visit to your lovely country, and it seems like an awesome place to do bonsai. I even got to visit the garden of Danny Use in Laarne, which I highly recommend.

Watering is tough. It's the last thing an apprentice is allowed to do in Japan, and even then they will not get it right immediately. Every professional I know of emphasizes the key to getting timing of watering really dialed. But the trees they are talking about are extremely refined and likely very old plants. It's true that it's important to the health of the plants, but it's far more important to older, more established trees.

It's not clear from your post, but do you "broadcast water", in other words, water all your plants at every watering? Or do you inspect each individual plant for its water needs? It is recommended to do the latter, and often check your collection multiple times per day when the days are long.

This is pretty normal. It's the hardest part of the whole practice and lifestyle.


Probably best to water in the morning as a routine if possible. Watering after sunset can cause issues of fungus and other nasties. A tree doesn't generally draw much water after dark


This again is natural. There's a degree of truth that it's better to play it safe, but if it's too "safe" that your trees never thrive, it's not really safe at all. Glaucus hits on this very well; acute v chronic.

I do believe that I see many more beginner trees that show signs of over watering than of underwatering. Maybe that's because the latter are dead, but I think overwatering is probably a bigger challenge in the community than underwatering. I think most people start out underestimating how dry a tree should get between waterings, particularly for pines and other dry conifers, or even maples.

I don't say this to discourage, in fact the opposite! All the things you're worried about are likely important and worrying about them is the first step to overcoming the challenges and achieving your goals.

Most of my trees are from Danny. The nursery there really is a bonsai paradise.

I check every tree before watering. If i see that the top soil is still wet to the touch, I don't water it unless I know the next day will be very hot.
I find this to be pretty difficult to assess with inorganic soil though. I also started using the chopstick method and that tends to help out a bit.
The biggest issue I have is that im at work during the day, so I can only check my trees in the morning and in the evening. If i was able to water in the middle of the day as well, I wouldn't be concered about my trees drying out.
The problem I often face is that watering daily is a bit too much, but watering every 2 days is not enough.

Watering during the hottest summer days is simple. The soil dries out quick so I can perfectly water every day. Winter and fall is just as easy because there I only need to water every week or so.
But these soft summer days are very tough to gauge.

 

[Jrmcmich]

Most of my trees are from Danny. The nursery there really is a bonsai paradise.

I check every tree before watering. If i see that the top soil is still wet to the touch, I don't water it unless I know the next day will be very hot.
I find this to be pretty difficult to assess with inorganic soil though. I also started using the chopstick method and that tends to help out a bit.
The biggest issue I have is that im at work during the day, so I can only check my trees in the morning and in the evening. If i was able to water in the middle of the day as well, I wouldn't be concered about my trees drying out.
The problem I often face is that watering daily is a bit too much, but watering every 2 days is not enough.

Watering during the hottest summer days is simple. The soil dries out quick so I can perfectly water every day. Winter and fall is just as easy because there I only need to water every week or so.
But these soft summer days are very tough to gauge.

Agree on being challenging with work. I’m in same boat and almost all mine are in plastic pots vs shallow bonsai pots so probably have more room for error and sure once in a bonsai pots I would Err on side of watering in morning on a hot day but then would be in inorganic soil so much easier not to over water from my limited experience.

 

[LeftHandLuke]

purely organic soil.

I think any time you have a tree in purely organic soil ("substrate"), you run the risk of root rot. I've lost more trees to that than anything else. When I hear "purely organic soil," I'm picturing that stuff you get at the garden center that's black, spongy and always wet... mostly peat moss. Organic bonsai soil ("substrate") is very different. It drains freely and the only organic material is pine bark nuggets... a radical difference from the peat moss sponge. I've come to believe over-watering is a myth, as long as water is free-flowing in fully draining substrate and the tree is not overly root bound. There's also some science around planting in a way-oversized pot. Someone could provide the background or you could look it up, but trees like to be stepped up gradually. Huge pot + spongey soil typically equals drowned tree.

 

[luvinthemountains]

It is one of those questions that is easy to worry about, much less easy to answer. Someday I might spend a weekend weighing one of my least favorite bonsai hourly after a single watering. My thinking is that the change in weight (from transpiration/evaporation) is likely to start leveling off at about the point when the tree needs to be watered again. If the tree goes crispy after that test, then I will need a new hypothesis...