STEM education in general. Rotala and Ludwigia in particular.

[JDCNY]

I could use some advice on a freshly planted 15 inch cube (~15 gal) and my first real aquascaping attempt after a long time fish keeping and a short time keeping live plants beyond the occasional low maintenance one that managed to survive my ignorance. It's a low tech tank that I'm not planning on heating planted with anubias (barteri and petite), crypt wendtii, java fern, ludwigia deep red, rotala nanjenshan, and salvinias. I've grown all of the plants in other tanks, but the stem plants are new to me. My hope is that they'll grow faster and thus help consume excess nutrients, keeping things balanced and filtered in such a small tank. This is assuming I can keep them alive!

I have them in the back corner of the tank and though the tank is 15 inches deep, I raised the substrate in the back so that they are in ~8-10 inches of water and directly beneath the light (Nicrew Reef 30). The crypts and the anubias are in deeper water and more shaded areas. Substrate in the back is Fluval Stratum with a thin top of  natural gravel. I dose with Easy Green and Seachem Potassium. I have the Easy Root Tabs too but wasn't planning on using them with the Stratum substrate. I have one of Cory's small sponge filters that I had running in another tank to get it "cycled" and I added some beneficial bacteria, but beyond that the tank is brand new. Aside from one ramshorn snail, there's no livestock and I don't plan on adding any until I'm sure I've gotten the plants well established. 

I'm a little worried that I planted the rotala too densely (see photos). Should they be thinned out or spread out more to allow the light to penetrate and provide more circulation? Too be honest, I was going to go with only ludwigia in the back and had only researched that. The owner of my LFS talked me into the rotala as a nice contrasting plant, but now that I'm looking into it, I'm concerned that it might not be the best fit for my aquarium since my water is hard, my pH is high, and I wasn't planning on heating the tank. I explained all of this when buying and in general, they have never steered me wrong and have always sold me super healthy plants and fish so fingers crossed. That said, any advice to help me give these plants the best chance at survival is appreciated. 

[Jungle Fan]

@JDCNYWith the stem plants make sure to give them some space in between like about an inch, so they have room to grow and are able to receive light for their leaves.

[gardenman]

7 hours ago, Jungle Fan said:

@JDCNYWith the stem plants make sure to give them some space in between like about an inch, so they have room to grow and are able to receive light for their leaves.

Exactly what I was going to say. Your bunched plants are too bunched as planted. I tend to plant mine a half inch or more apart. If they're still bundled with a rubber band or weight, unbundle them. Keeping them planted will be a challenge as they like to float free until they get well rooted, but they do need space between each stem. 

[JDCNY]

Thank you for the advice. Since there's no live stock, I drained the tank and planted the stems one at a time. It was a PITA so I can't imagine doing it in a fully flooded tank! When all was said and done, I ended up using a third less ludwigia and probably only half of the rotala. Despite cutting down on the total quantity, it actually looks more full and lush now that it's planted properly. 

I figure I'll have to do it at least once more after the emerged leaves melt back and the new submerged ones grow. We shall see.

 

[Jungle Fan]

You'll note that once the stems have rooted your plants will lose less leaves if they are planted with enough space in between each stem now because they are getting enough light to sustain them. When you plant stem plants remove some of the leaves on the bottom of the stem to give you enough space to plant them. I use an angled pair of aquatic gardening tweezers to plant them at a slight angle it helps getting them anchored in an established tank.

A friend uses some super glue applied to a small portion around the stem and rolls that portion in aquatic soil so some of the grains attach themselves to the stem and can act as an anchor when the plant is planted.

[PlaneFishGuy]

@Jungle Fan and anyone else.... I have some ludwigia repens that have gotten leggy to the point the the bottom halves have no leaves - I plan to spread the bunches out better as discussed above to address the root cause (no pun)  

how far back can I cut them back and expect to get any new growth? Ive seen some articles say nothing will grow if you cut below the lowest leaf of a stem plant. Any real-world experience?  

Will it correct itself if lighting/spacing issues are addressed?

Edited April 6, 2021 by PlaneFishGuy

[Jungle Fan]

@PlaneFishGuy I generally agree with the statement of not leaving bare stalks and hoping they will recover, although I've seen some where they had two, or four leaves after they were cut and then lost all four but still recovered but I would not count on the recovery of mere stalks as general practice.

As best practice I would leave at the very minimum four, or five leaves but the more you can leave the better so the plant can use fertilizer, CO2, and light to photosynthesize to be able to produce new growth.  I know it's sort of an off comparison, but think of the Ludwigia's leaves as the solar panels it needs to create energy, the bigger the surface the more energy you get. As to experience, it has always worked for me in conjunction with fertilizer, light, and in my case CO2.

As to answering your question if it will work, it should as long as you provide all the elements the plant needs in regard to light (spacing so that light can reach the lower leaves is part of that, just like timing, and intensity), fertilization (the Easy Green dosed according to your tank size, and root tabs because Ludwigia is a red plant and craves that extra iron), and although not absolutely necessary, but a great asset if you can provide it, CO2 with which plants will always grow better, and faster, and have a much better chance to out-compete algae for nutrients. That said added CO2 is not absolutely necessary for Ludwigia but it might take longer for the recovery process so you will need to give it time.

The picture is a fisheye orb shot I took of my 75 gallon tank but behind the stump with the Java fern, and the Pogostemon erectus, the reddish plant is my Ludwigia repens.

I hope this helps.

[gardenman]

I recently mail-ordered some ludwigia that was supposed to be 5"-10"  tall. It was more like 24" tall. I cut it into more manageable lengths and was left with some bare stems. I went ahead and planted them anyway and they're growing very well with multiple shoots emerging. Also roots are emerging so those bare stems could be made into multiple new plants if I needed them. Ludwigia is a pretty tough little plant. Photo below of one pot that was mostly all just bare stems when I planted them with no leaves. As long as you leave a leaf node where a dormant bud is lurking, you should see new growth.

[JDCNY]

Mine seem to grow extremely fast with Easy Green and Fluval stratum. If you cut them just above a node where the leaves come out, you'll get two new stalks that come out of the cut. If you get into a decent cutting routine and do it regularly, they'll get bushy pretty quickly. Plus, planting the trimmed part next to it pretty much doubles your bushiness. I find that the trimmed tops grow even faster than bottoms and in that case you may just have an inch or two of stem and with a nice leaf cluster on top.