How tall do submerged aquarium plants grow?

Figures are approximate, as they say.  When planning a planted aquarium (and there should be some type of plan!) it’s important to consider the expected maximum height of plants in the layout.  I went wrong previously planting echinodorus radicans, a fine plant but much too large for this aquarium.

After not trimming back the ludwigia last week today it managed to reach the surface of the water.  This version of ludwigia, ludwigia mini ‘super red’ is listed online as “Dimensions: grows up to 30cm” however in this aquarium it is 41 cm from the aquasoil floor to the water surface, so this plant has overachieved.

I can’t complain and I’m glad it’s healthy.  I’ll give it a trim today and replant some of the better looking top portions to have it fill in a little to the right.  Stem plants like the ludwigia are pretty flexible that way:  you can trim them to pretty much whichever height works for you, just the growth rate and how much you trim will determine how often they will need this type of maintenance.

Afternote: 
Digging around a bit more on the Tropica entry for this plant it says in the “Plant info” section in the ‘Height’ entry if you click on the +/- expander button:

Height:	10 – 30+
Average height (cm) of the plant after two months in the tank.

so to be fair there is a little + sign after the 30 and it does say ‘after two months’ and it has been three months in tank (nearly to the day) since it was planted, so I suppose it’s “fair play” to the description, even if 30+ is actually 41…

Ludwigia palustris mini ‘Super Red’ can go back to green at the water surface

Just to see what would happen, another time I let the ‘Super Red’ go for much longer than I otherwise would have and it reached the top of the water and kept growing.  It kind of piled up on the surface without reaching directly through and I noticed that the new growth at the surface had green foliage rather than red.  When first planted back in the day the emersed form of the young Ludwigia was also green rather than red, and it seems the red colouration may be exclusive to the submerged form.  The pile of Ludwigia floating on the surface was shading everything underneath so I did eventually take it all out and replant the tops.  Ludwigia tolerates this procedure really well and I have successfully done this a number of times now without adverse findings.  Some of the ‘mini’ stems had comfortably exceeded 50 cm in length, so the ’30+’ guidance from Tropica could fairly be listed as 40+, or maybe 30+++.  Once back to being fully submerged, the new leaves produced subsequently were back to the usual bright red colouration.

Today I gave the ludwigia palustris its first trim. A couple of the stems were just under the surface so I clipped off the three tallest.  This ludwigia, in contrast to some reports, doesn’t have very many aerial roots but where there were a few part-way down the stem, I trimmed to just above the node below the roots to allow (hopefully) new growth, then clipped off the stem to just below the node where the roots are and planted those pieces on the far left of the tank in a region that was more thinly grown, very likely due to less light off to the side and in the shade of the taller stems in the centre.

I was following this guide to trimming stem plants from dw1305 so we’ll see how that goes.  Seems straightforward and reasonable.  There was some question as to whether the shrimp would just immediately dig up the newly planted tops, but happily that hasn’t happened yet.