Can't Keep Up With Watering... Water retentive but Bonsai acceptable substrates?

[kev2712]

Hello.
Advanced gardener but bonsai newbie. I typically dabble in fruit trees and veggie gardens outdoors, and tropical plants indoors. I'm really enjoying Bonsai and learning a lot from the wealth of information available here at Bonsai Nut.
I'm having an issue though that I'm looking for resources for. Links and info appreciated. Thanks in advance.

I have mostly pre-bonsai technically, but I still call them my bonsai . I keep them in bonsai pots for aesthetics. Mostly conifers (spruce and pine) at the moment, but considering collecting a local deciduous tree. These live outdoors, but I frequently bring them inside (I like to look at them, and don't trust the crows in my area...)..

My issue is - I simply am really struggling to keep up with watering. I have a busy life with a young family, lots of travel, sports, activities, etc - and I cant always give these bonsai the attention they deserve from a watering perspective. I feel like on days it does not rain, the soil is in need of watering either every day or every other day. Most of the time that's fine - but some weeks that's simply very difficult to do. I'm aware I could setup a sprinkler/dripper system on a timer, but that's a last resort for me - as I do enjoy watering with a hose/can.

So - how can I make my soil more water retentive WITHOUT bogging down drainage? What are the most water retentive components that are acceptable/encouraged in Bonsai practice? As a frequent gardener I love my organic soils and composts, but recognize that is generally not a good idea in these wide, shallow, bonsai pots. My current mixes (all aggregates are 1/4in) are either "33% Scoria / 33% Pumice / 33% Pine Bark" or "80% pumice / 20% organic potting soil". The former is the healthier mix I am sure but I have to water often, the latter is I think generally discouraged but it does retain more water due to the organic soil.

I've also studied https://www.bonsaijack.com/blog/author/storeadmin88/page/83/ (Bonsai substrate test report) and while very interesting - my main takeways were bark retains the most water and expels quickly, turface retains moderately but doesnt give back much, and akadama performs similar to turface but a little better. Charcoal performs well as for as retention and release, but has other issues and probably cant be a large percentage in the pot. Everything else is just a stinking fast draining rock ! haha

What to do ? Am I missing something that could increase overall water retention, to the point where I could water every 4-6 days ? Or do I just need to get over it and accept that daily watering is a part of bonsai practice?
Thank you

 

[Shibui]

There's not much that can retain water but drain well.
My mix is mainly pine bark because most inorganics dry out way too fast for my conditions here. I still need to water twice a day through most of Summer. A watering system keeps things alive through the occasions when I can't be here to water.
Bonsai will grow in almost any soil mix. The key is to manage watering to match the characteristics of the soil mix. If you need something that will retain water for a few days at a time that's OK BUT you'll also need to water only when it needs water - every few days. Rainy weather and wet winters may cause problems when using such a mix. It is certainly easier to add water with a sprinkler system and timer than it is to protect your pots from natural rainfall.
I doubt you'll find any mix that will last 4-6 days in summer, even with trees in larger training or development pots. Even commercial nurseries need to water daily through the warm season and they don't push the limits of plant size V pot size like we tend to do.

I would set up a watering system to cope with the times you can't be there. You can always turn it off and hand water when you are home if that's what you want.

 

[leatherback]

Next to what Shibui correctly points out, look into coco coir substrates. They retain shape and consistency, yet hold a lot of water.

 

[Glaucus]

Or put your bonsai in normal garden plant pots. Not shallow pots. Then you can use soil. Then they are normal plants, except you train them.
Or there may be a middle ground. Deeper pots than usual, part soil/organic matter, part substrate.
Probably harder to find ornamental affordable pots that shape and size, though.

Automated watering could also be a nice thing. Even if you put things in large pots, if you are busy and you miss manually watering them, then that's still bad.
Even with large pots, in summer you often have to water daily anyway, like Shibui says. Sometimes, two times a day.

 

[penumbra]

Its hard to balance bonsai keeping with an active lifestyle. I really think that in your case you should consider a watering system that is automated.

 

[rockm]

Bonsai require attention, period. No way around it. They're like dogs and are are dependent on you for their needs. Watering is a critical part of their care. You have to make accommodations (and sometimes those accommodations wind up killing your trees), FWIW. Automatic watering systems are the answer for your situation, but those can't really respond to the day-to-day needs of your trees and local weather (particularly in summer with thunderstorms, heat, etc.) They can work, but they're not as good as having an actual person do the work. Got a neighbor/relative etc. who can come over and water? (also some pet sitters can offer plant care services as well sometimes)

Water retentive soil is not a great thing to use, since it retains too much water for too long--see above thunderstorms etc. If weather brings a lot of moisture that stays in the roots, trouble can ensue.

 

[JudyB]

I agree with an auto watering system, it's the only way in the summer that I can still live the active life and not worry about the trees. You will find lots of info here about different types of systems, I use an overhead mister head setup.

 

[Paradox]

Also agree with an automatic watering system. Trying to find a more water retentive soil for 4-6 days is going to lead to disaster.

You can still walk out among you trees when you can and examine them. You should do this anyway to keep an eye out for trouble.

Either automate your watering system or reduce the number of trees to a more manageable number.

I use a automatic system and I love it

 

[Michael P]

In my climate with hot and dry summers I use several techniques. My mix is at least 25% organic. Smaller particle size retains more moisture. My trees are in larger pots than would be considered aesthetically ideal. In really hot weather I move trees into the shade of large landscape trees. None of this gets me to the 4-6 day range, but they help.

 

[ShadyStump]

I simply am really struggling to keep up with watering. I have a busy life with a young family, lots of travel, sports, activities, etc - and I cant always give these bonsai the attention they deserve from a watering perspective.

I am in a similar boat: single working father of 4. I'm broke as they come and still able to contemplate having hobbies, but a water timer is a priority expense for me. Otherwise I have no trees, no vegetable garden, no herb garden, no flowerbed. In other words, in order to ensure these things that keep me sane are there when I'm able or in need, I've had to accept that it won't look like I'd really like it to, but damnit it'll look like something.
Simply put, you have to set some priorities, and embrace the consequences. Also, just accept that every other day watering is about as good as it gets regardless of priorities or climate.

And also add a general location to your profile. Knowing the climate you're managing will help allot, and there may be some here who lives in your neck of the woods who can help better than our random mutterings.
Oh, and welcome to BNut!

Some general tips:
A layer of sphagnum moss or similar on top of the soil can help allot.
Move your trees to somewhere the hottest afternoon sun doesn't get them. That alone can buy you a few hours.
People sometimes wrap their pots in towels when they need to buy an extra day.
As said before, smaller particle size retains more water.

Getting into substrate composition can be quite the rabbit hole to fall down. There are some excellent resources posted here, most notably markyscott's Introductory Soil Physics.

Akadama is generally considered top tier for the drainage/water holding compromise, but can break down into unbreathable sludge depending on the batch, and can be quite expensive if you can even source it.
Many of us cheap bastards will go with Napa's oil absorbent part number 8822. Pure diatomaceous earth; so holds up well enough, retains moisture well enough, cooperates with fertilizer well enough. May not have the water holding you're really hoping for, though.
Safety-Sorb is a similar product but more widely available in North America. Fuller's earth, a type of clay. Breaks down quite a bit faster, but otherwise similar performance as above, but also holds water a bit better.
As @leatherback mentioned, coco coir. When using organics in your substrate, it cannot be beat for it's balance of water retention and breathability.

And you may very well just be stuck with a timer regardless.
You can always set it for just under your trees' requirements, as a time buyer. Enough time that you can water again whenever you want, but plenty enough that your trees won't die if you get swamped for a day or two.

 

[Dogestoevsky]

Very similar lifestyle / family situation here with young kids. My two cents:

-if most of your stock is young pre-bonsai, don’t forget you can ground grow— trees are way less vulnerable to drying out!

-find a young apprentice who can handle your garden while you are out there making the big bucks or out of town. My neighbor kids are wonderful. Not really into bonsai, but they get some spending money and I send them home with fresh veggies for their parents. Everyone wins!

 

[dbonsaiw]

disclaimer - I don’t recommend this. But I ran out of soil in the beginning of spring and still picked up a new blood good from Home Depot. I repotted it into a grow box and back into its original soil - what looked like a 100% bark soil. The drainage is excellent and I can’t make the soil float with the wand even if I try. It does stay wet however. Again, I don’t recommend this but it seems to be working so far with this tree and it will only be for one season (assuming it lives).

My neighbor kids are wonderful. Not really into bonsai, but they get some spending money

Same. This has worked pretty well for me the few times I travel.

 

[PowerTap]

I have two kids and travel occasionally for work. I use this hose timer and a small irrigation setup I built from a kit from Home Depot. I've gone camping for a week in 90 degree heat and been happy to be able to turn on an extra watering cycle from my phone when it is really hot.

B-hyve Smart Hose Watering Timer

B-hyve Wi-Fi enabled smart hose watering timer lets you control watering from anywhere via smartphone. Available now directly from Orbit at orbitonline.com.

www.orbitonline.com

I also like that it will skip watering if it's going to rain, not that I have much trouble with that here in the Seattle summer.

 

[BrianBay9]

If you're busy times are in any way predictable, you can make a sand table and sink your pots in the sand when you'll be away. Water well and the sand stays wet for quite a while, making water accessible to your trees without changing substrate. Take them out of the sand table when you're home and hand watering.

 

[R0b]

More retention in summer also means that if you have a wet season you will might need to protect against rain.

Others referred to this but it will help to understand the linked information https://www.greenhousestudio.co/home-garden/pot-plant-size-shape

 

[Ply]

Or put your bonsai in normal garden plant pots. Not shallow pots. Then you can use soil. Then they are normal plants, except you train them.

I second this, pot size is gonna be a big factor. Even a much more water retentative mix is going to dry out quick in the super small pots we use in bonsai. Using larger pots will allow you to have a well draining substrate that won't dry up within a day. Especially if you use full inorganics and put the bottom of the pot in a tray of water you can stretch it multiple days easily. In fact this is what I do with some of my ficus (bonsai) in training.

Ofcourse you are stepping away from traditional bonsai. Small pots are inherent to bonsai, but there's no reason why you can't style a tree or plant with bonsai aesthetics in a bigger pot.