Umbrella Thorn substrate choices

[abugoogoo]

Morning guys n gals,
I have some umbrella thorns that I started from seed about a year ago. I repotted the 3 survivors, along with some new seedlings yesterday. I went with a mix of 50/50 lava and pumice, with some desert sand thrown in, as the reading I've done on these says that they like rocky/sandy alkaline soils. That being said, I'm now rethinking this for several reasons, and I need some advice. 1) the sand is pretty much gone after watering, I guess I used stuff that is too fine and it all washed out. 2) the lava and pumice seem bone dry to me, immediately after watering. All of my other stuff is growing really well in a mix of lava and pumice with some Happy Frog in the mix (I'm in South Florida BTW). This is the first time I've gone 100% inorganic. 3) When I originally transferred these as seedlings into 4 inch pots, I put them in varying amounts of components from almost 100% organic with some volcanic for drainage, to 100% volcanic. The three that survived had significant amounts of the Happy Frog in it, and the one that was doing the absolute best yesterday when I repotted them, in terms of root structure, and the only one that was able to support itself completely upright was probably around 60 to 70% happy frog. I'm thinking about repotting these one more time today with a buncha soil in them, but I wanted to ask for your thoughts first, and if I should do it, or stick it out with what I have now. Ima include some pics for you. You'll excuse the chopsticks and butchers twine, these 2 needed a lot of help standing up.
Also, one more question. If I do stick with what they're in now, how long after repotting should I fertilize? Thanks folks, I appreciate you alot, sorry if these are dumb questions.

 

[sorce]

Might as well leave em now.

And start some new seeds too!

Sorce

 

[abugoogoo]

Might as well leave em now.

And start some new seeds too!

Sorce

Yeah, I've got a bunch more seeds going and gonna start some new ones. From what I've seen of your posts, I think you do the 100% inorganic, correct? With what I have these in right now, and as dry as they seem to me, do you think they'll be getting enough water? Is there anything that I can do to increase water retention at this point without changing the whole thing around?

 

[sorce]

My stuff is probly more organic that inorganic due to the remaining nursery soil.

Worms live in it!

You can throw some moss atop it....
But I wouldn't do it right away...
Get to know what that soil is doing itself first.

It may look dry. Weigh it.

Sorce

 

[abugoogoo]

My stuff is probly more organic that inorganic due to the remaining nursery soil.

Worms live in it!

You can throw some moss atop it....
But I wouldn't do it right away...
Get to know what that soil is doing itself first.

It may look dry. Weigh it.

Sorce

OK, thx much 4 the help

 

[penumbra]

Is that an Acacia?

 

[abugoogoo]

Y

Is that an Acacia?

Yes, sure is

 

[abugoogoo]

My stuff is probly more organic that inorganic due to the remaining nursery soil.

Worms live in it!

You can throw some moss atop it....
But I wouldn't do it right away...
Get to know what that soil is doing itself first.

It may look dry. Weigh it.

Sorce

Did what you said n left it alone and weighed them in 12 hr cycles for 2 days in a row after watering... They're most certainly not dry, it's holding water really well, and all of them are looking super happy. Thanks for the advice!

 

[sorce]

Thanks for the advice

No problem, I'll send the thanks out to Grandma's world-wide!

Sorce

 

[jason biggs]

all my acacias thrive in potting soil. Your mix looks way too technical and dry....
especially while they are small pot them in bigger pots and let the roots grow

 

[Carol 83]

all my acacias thrive in potting soil.

So is that what you would recommend? I have a rabbit's foot acacia (dichrostachys cinerea) arriving today. I believe it will planted in soil conditioner when I receive it.

 

[Leo in N E Illinois]

For bonsai, slower growth with tight internodes is what gives the impression of greater age. An all inorganic media will keep the growth of the seedlings slower. The beauty of an all inorganic media, is you can water daily and never over-water. Pumice-lava mix will hold quite a bit of water even though the surface is dry to the touch. If you are able to water daily, the fact that it is difficult to over water a pumice - lava mix is a bonus, when in doubt, just water. Every time you pick up the pot, notice the heft, you don't need to weigh it on a scale. In a week or two you will notice you will immediately know whether it is wet or dry by the heft of the pot. The scale is good to help calibrate your sense of heft.

Organic mixes, especially potting soil, have a lot of fine particles. Fine particles can hold so much water that the water closes the air voids, roots can be deprived of oxygen, root tips die, fungi & bacteria opportunistically move in, and the tree can die of rot. The rots won't happen as easily in an all inorganic soil. It is very possible to over water a potting soil, or a bonsai medium with a high amount of organic material. Especially fine, small particle size organic materials, can block air movement. Organic media holds a lot of water, if you can not water every day, often using organic media, like composted fir bark can increase the amount of water your mix holds and give you a day or two buffer. But this extra water holding capacity is a liability if you do not have good air penetration into the mix.

Organic mixes are more difficult to get the watering frequency "just right". It is possible to keep them too wet. When they get too dry, sometimes they are difficult to re-wet, especially if peat is one of the components.

Advantages of organic materials include they are more "hospitable" to mycorrhiza, the symbiotic fungi most trees and shrubs have associations with. Organic materials tend to have a higher CEC, cation exchange capacity, they "hold on to" fertilizer components more so than inert materials like lava & pumice. This means that fertilizer is not totally flushed out the next time you water with clear water. So mycorrhiza and fertilizer holding capacity are reasons one can get quicker growth in organic media. Growth in a partially organic to completely organic mix can be very rapid, with long internodes and too coarse for bonsai. Not always, but coarse growth can happen more often in organic mixes than inorganic mixes. Rapid growth is good if your are bulking up a trunk, and are not worried about refinement.

Sifting your media. A set of bonsai sieves is critical. If you sift your organic media, throw out anything that goes through the fine screen, 1/8 th inch screen, or window screen if you make your own sieve, this will go a long way to fixing the problem of air penetration that organic mixes have. An organic mix, that has been sifted to eliminate all fine particles will perform very well, and be less prone to problems from being overwatered.

Myself I like a mix with an organic component. I NEVER use potting soil. My preference. I have had trouble with potting soil, the fines plug up air voids and don't breathe enough for the way I water. I use douglas fir bark, the fine chips sold for seedling orchids. I sift my mix. My typical mix is pumice 50%, lava 25%, and fir bark 25%. I will vary the mix, for conifers I use the same mix, but the fir bark reduced to 10%. This is fine.

I have on occasion have used 100% inorganic, all pumice, or pumice-lava. This is fine for pines, spruce and other conifers, though I do like the mix best when it is about 10% bark.

I also use Akadama and Kanuma when I can get a good grade. The latest batch I got has turned out again to be a crappy grade that broke down to mush over winter while sitting in my storage shed in the original bag. Not being able to read Japanese I can not tell the good Akadama from the crappy Akadama. I find this product expensive and very unreliable in quality. When it is good it is great, when it turns to mush, it forces me to repot way too soon.

For your Acacia tortilis, also known as Vachellia tortilis, also known as Umbrella thorn - I would not repot again for 2 years. Mess around with them too frequently and you will "love them to death". Give them a chance to grow. The Umbrella acacia is a tree of the savannas of the Sahel. This is near desert, more or less a dry grass prairie setting. They will endure drought. So the all inorganic, pumice-lave mix is just fine. It will survive getting dry between watering. If it dries to the point were leaves wilt and drop, very likely it will resprout when it is kept moist again. In the future, you can change the mix after allowing at least one year to recover between repotting. They are forgiving, you can continue inorganic, or switch it to a different media.

@Carol 83 - Dichrostachys cinerea -Rabbit's foot acacia - this is a tree from higher rainfall areas, actually prefers to grow in rain forests. This species demands more water than the Vachellia tortilis. It is world wide considered an invasive species in rain forest areas, so it is pretty resilient plant, but it definitely is not the desert or savanna dweller that the Umbrella acacia is. Carol, I would use the same potting media you are using for your Bougainvillea and Ficus. (yes, I would use my Ficus mix on my Bougainvillea). Nothing special or unique needed for the Rabbit's foot acacia.

 

[Carol 83]

Carol, I would use the same potting media you are using for your Bougainvillea and Ficus. (yes, I would use my Ficus mix on my Bougainvillea). Nothing special or unique needed for the Rabbit's foot acacia.

Thanks Leo, as always I appreciate your help. I may just let it go this season without repotting, to let it settle into it's new environment. Andrea recommends not to repot too soon after receiving. I don't always follow that advice, we'll see how bored I get staying at home for another month.....

 

[abugoogoo]

For bonsai, slower growth with tight internodes is what gives the impression of greater age. An all inorganic media will keep the growth of the seedlings slower. The beauty of an all inorganic media, is you can water daily and never over-water. Pumice-lava mix will hold quite a bit of water even though the surface is dry to the touch. If you are able to water daily, the fact that it is difficult to over water a pumice - lava mix is a bonus, when in doubt, just water. Every time you pick up the pot, notice the heft, you don't need to weigh it on a scale. In a week or two you will notice you will immediately know whether it is wet or dry by the heft of the pot. The scale is good to help calibrate your sense of heft.

Organic mixes, especially potting soil, have a lot of fine particles. Fine particles can hold so much water that the water closes the air voids, roots can be deprived of oxygen, root tips die, fungi & bacteria opportunistically move in, and the tree can die of rot. The rots won't happen as easily in an all inorganic soil. It is very possible to over water a potting soil, or a bonsai medium with a high amount of organic material. Especially fine, small particle size organic materials, can block air movement. Organic media holds a lot of water, if you can not water every day, often using organic media, like composted fir bark can increase the amount of water your mix holds and give you a day or two buffer. But this extra water holding capacity is a liability if you do not have good air penetration into the mix.

Organic mixes are more difficult to get the watering frequency "just right". It is possible to keep them too wet. When they get too dry, sometimes they are difficult to re-wet, especially if peat is one of the components.

Advantages of organic materials include they are more "hospitable" to mycorrhiza, the symbiotic fungi most trees and shrubs have associations with. Organic materials tend to have a higher CEC, cation exchange capacity, they "hold on to" fertilizer components more so than inert materials like lava & pumice. This means that fertilizer is not totally flushed out the next time you water with clear water. So mycorrhiza and fertilizer holding capacity are reasons one can get quicker growth in organic media. Growth in a partially organic to completely organic mix can be very rapid, with long internodes and too coarse for bonsai. Not always, but coarse growth can happen more often in organic mixes than inorganic mixes. Rapid growth is good if your are bulking up a trunk, and are not worried about refinement.

Sifting your media. A set of bonsai sieves is critical. If you sift your organic media, throw out anything that goes through the fine screen, 1/8 th inch screen, or window screen if you make your own sieve, this will go a long way to fixing the problem of air penetration that organic mixes have. An organic mix, that has been sifted to eliminate all fine particles will perform very well, and be less prone to problems from being overwatered.

Myself I like a mix with an organic component. I NEVER use potting soil. My preference. I have had trouble with potting soil, the fines plug up air voids and don't breathe enough for the way I water. I use douglas fir bark, the fine chips sold for seedling orchids. I sift my mix. My typical mix is pumice 50%, lava 25%, and fir bark 25%. I will vary the mix, for conifers I use the same mix, but the fir bark reduced to 10%. This is fine.

I have on occasion have used 100% inorganic, all pumice, or pumice-lava. This is fine for pines, spruce and other conifers, though I do like the mix best when it is about 10% bark.

I also use Akadama and Kanuma when I can get a good grade. The latest batch I got has turned out again to be a crappy grade that broke down to mush over winter while sitting in my storage shed in the original bag. Not being able to read Japanese I can not tell the good Akadama from the crappy Akadama. I find this product expensive and very unreliable in quality. When it is good it is great, when it turns to mush, it forces me to repot way too soon.

For your Acacia tortilis, also known as Vachellia tortilis, also known as Umbrella thorn - I would not repot again for 2 years. Mess around with them too frequently and you will "love them to death". Give them a chance to grow. The Umbrella acacia is a tree of the savannas of the Sahel. This is near desert, more or less a dry grass prairie setting. They will endure drought. So the all inorganic, pumice-lave mix is just fine. It will survive getting dry between watering. If it dries to the point were leaves wilt and drop, very likely it will resprout when it is kept moist again. In the future, you can change the mix after allowing at least one year to recover between repotting. They are forgiving, you can continue inorganic, or switch it to a different media.

@Carol 83 - Dichrostachys cinerea -Rabbit's foot acacia - this is a tree from higher rainfall areas, actually prefers to grow in rain forests. This species demands more water than the Vachellia tortilis. It is world wide considered an invasive species in rain forest areas, so it is pretty resilient plant, but it definitely is not the desert or savanna dweller that the Umbrella acacia is. Carol, I would use the same potting media you are using for your Bougainvillea and Ficus. (yes, I would use my Ficus mix on my Bougainvillea). Nothing special or unique needed for the Rabbit's foot acacia.

Thanks for this, great info