# Can elodea and hornwort be kept in jarrariums without being trimmed?



## Wayfarin (Apr 15, 2022)

This question is asking just what it sounds like it is asking. Can elodea (E. densa and canadensis) and hornwort (Ceratophyllum demersum) be kept in jarrariums, ecospheres, or nano tanks without being trimmed? Likewise, does water depth limit growth? For example, will a hornwort plant kept in a 2-gallon tank still grow to 3 feet tall? Or will it only grow 1-2 feet?

And if both elodea and hornwort are kept in a 2-gallon tank, will both of them grow to 3 feet, or will one of them stay small because it's being outcompeted by the other? What are the average sizes of these plants anyways? I've heard that hornwort can grow to 10 feet tall in the wild, but obviously that's not the average size in aquarium tanks.

I'm only asking because I've never had either plant before, and I don't want to obtain them until I'm sure about what I'm getting into.
If necessary, I might need to obtain smaller plants for my 2-gallon jarrarium.
For those who are willing to answer, thanks!

The problem with constantly having to trim them is that it would disrupt the inhabitants of the tank, all of which are fragile. Namely, amphipods, aquatic isopods, and bladder snails.


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## Smotzer (Apr 16, 2022)

Ceratophyllum demersum can grow quite large in water 6in to yes10ft, in a 2gal terrarium full of water you will likely yes have to prune it but it is propagated by stem cuttings so you can use this as an opportunity to make more. Elodea densa is known as Egaria densa, I assume this is what you meant , and Elodea canadensis may have to be pruned as well, both may. A lot of anything you use in a jar will have to be pruned at some point, that is to be expected.

Im not sure what will or will not outcompete there other, generally the faster growing species has the ability to outcompete the other if it grows slower. I don’t exactly know the growth rate of both in a jar. You’d have to experiment with that


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## Wayfarin (Apr 16, 2022)

Thanks for your reply.
The main goal of this tank is minimal disturbance, so if hornwort and elodea absolutely need to be trimmed, I might have to skip them and just add smaller plants to the tank, or upgrade to a tank that would more comfortably house them. Maybe 3-5 gallons?
I strongly despise the idea of pruning them. There's just too great a risk of harming the inhabitants or their eggs.

If it's not tank size, then what determines a hornwort or elodea cutting's full size? Sunlight? Nitrates?
And is the problem with the plants "overrunning" the tank purely based on visibility, or is there a more serious problem with this kind of overcrowding? I don't think that amphipods, isopods, and snails need a lot of free space...


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## Frogdaddy (Apr 16, 2022)

They will both grow to the point of floating on the surface and blocking all light to the lower levels. It has to be trimmed, no two ways about it.

Reactions: Agree 1


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## Wayfarin (Apr 16, 2022)

Frogdaddy said:


> They will both grow to the point of floating on the surface and blocking all light to the lower levels. It has to be trimmed, no two ways about it.


But why does the bottom need light? And doesn't light penetrate through the glass to reach the bottom? It's not like a pond that only receives light from above.


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## Frogdaddy (Apr 16, 2022)

The ambient light that penetrates the glass would not be sufficient for plant growth. 
If your hornwort and Eloda are the only plants then no light penetration on the bottom is not a big deal. If you had shorter plants, baby tears or Ricca or some other moss type they wouldn't get enough light.


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## Wayfarin (Apr 16, 2022)

So let me get this straight...

Here's the two-gallon jar...



Here's a Christmas garland that measures roughly 5 feet in length when stretched out...



Here it is in the jar...



So, would this be decent estimate of how much space would be taken up if both plants were to be added to the jar?



Frogdaddy said:


> The ambient light that penetrates the glass would not be sufficient for plant growth.
> If your hornwort and Eloda are the only plants then no light penetration on the bottom is not a big deal. If you had shorter plants, baby tears or Ricca or some other moss type they wouldn't get enough light.


Considering the amount of space that they would take up, they would certainly be the only plants in the jar. I had considered adding duckweed, but I wouldn't want to deprive the others of light by covering them up, should a duckweed "explosion" occur.

Reactions: Like 1


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## Frogdaddy (Apr 16, 2022)

Wayfarin said:


> So let me get this straight...
> 
> Here's the two-gallon jar...
> View attachment 415796
> ...


That's probably what it will end up like if you don't trim. I don't know how fast they will grow, that depends on a number of factors. But you're definitely looking at periodically removing the plants, trimming them, and replanting.

Reactions: Agree 1


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## Wayfarin (Apr 16, 2022)

Frogdaddy said:


> That's probably what it will end up like if you don't trim. I don't know how fast they will grow, that depends on a number of factors. But you're definitely looking at periodically removing the plants, trimming them, and replanting.


Would they suffer if they were left to grow freely? The only inhabitants of the jar would be isopods, amphipods, snails, and perhaps some insects, worms, and planaria, so I'd be more concerned about the plants overcrowding each other than the animals not having enough space.
It would be an eyesore, but the only thing that would concern me would be the stability of the habitat, not the appearance.


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## Smotzer (Apr 17, 2022)

If you are worried about this being your first time doing such and worried  about pruning disturbances than I would likely choose different plants. You in time are going to 110% have to prune with the choices of plants you have selected now.


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## Wayfarin (Apr 18, 2022)

Smotzer said:


> If you are worried about this being your first time doing such and worried about pruning disturbances than I would likely choose different plants. You in time are going to 110% have to prune with the choices of plants you have selected now.


I'm reluctant to do so because I'm very fond of the oxygenating capacities of these particular plants. It's also somewhat of biotope aquarium of our region, which is New England, so I wouldn't want to go with any plants that are of exotic origin. If absolutely necessary, I might upgrade to a larger tank.



Smotzer said:


> If you are worried about this being your first time doing such and worried about pruning disturbances than I would likely choose different plants. You in time are going to 110% have to prune with the choices of plants you have selected now.


What will happen if I don't prune them? Will they just keep growing until they crush everything and kill themselves? Do they ever stop growing?
And if so, at what size?

Perhaps you're aware at this point of how persistent I am.


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## Wayfarin (May 6, 2022)

Maybe I'll just keep one of the plants? Maybe the hornwort?

Would the elodea and hornwort need to be trimmed in a 10-gallon tank?


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