Rotala is widely-considered a hallmark of aquarium plants — it’s easy to grow, not picky about water parameters, and looks great under higher-light conditions. Let’s take a quick look at some specific for the species:
visual appearance
This plant varies significantly depending on its environment. However, it’s important to note that there are some species in the Rotala genus that are mislabelled. Rotala Indica, Rotala Colorata, Rotala H’ra, Rotala Bonsai, and others are occasionally misidentified and sold as Rotundifolia, so it’s critical that you determine which species you have in the Rotala genus.
Note: if you want the beautifully-red, bushy appearance of Rotala, you’ll need high-light conditions (i.e. 75PAR or greater.)
This species grows fast — it’s best-suited as a background plant. If you’re planting this species within a high-tech tank, expect to trim at least once per week once it’s established.
the name matters
rotala rotundifolia is the scientific name of the plant — its genus is Rotala, and the species is Rotundifolia. Note that there are other species within the Rotala genus, including Colorata, Bonsai, ‘Red’, and others. Each of these is a completely separate species of plant, and should be treated separately.
With high light and proper nutrients, Rotundifolia turns a vivid red color desirable in many aquascapes. Its leaves also take on a more pointed, ‘razorlike’ shape and will often exhibit ‘pearling’.
In medium/low light tanks it’ll keep its usual green appearance. Note that etiolation in this species (in layman’s terms, a plant’s “striving” towards a light source) results in especially-negative appearances, creating the common ‘spindly stem’ look seen in many beginner tanks.
rotundifolia’s water parameters
This species is a perfect example of the ‘standard’ parameters in aquascaping: a specific set of ranges at which you can keep most aquatic plants. (More on the Standard Parameters here.) In this range most any aquatic plant will survive.
For Rotala Rotundifolia to thrive, using water parameters close to those shown below have triggered lush, active growth in this species:
- pH: 6.5−7.5
- GH: 4 – 6
- KH: 1 – 4
- Temperature: 70 – 82º F (21 – 28º C)
- Lighting: High, 8 hours
Adhering to these values will give you healthy, robust growth with Rotala Rotundifolia. (And most other aquatic plant species.)
In general: keep your water parameters correct and stable, and you’ll have no problems growing this species.
the importance of temperature
If you’re a newer aquarist that’s not seeing the vigorus growth that’s expected from Rotala, you’ll likely tend to investigate nutrients/pH/lighting before you consider temperature.
Within reason — this is a mistake. Assuming your water parameters are even close to ideal for this plant, you’ll get much faster growth by ensuring your water temperature is 75 – 80º F. This plant loves warmer water.
trimming and propagating rotala
rotala rotundifolia is an extremely-fast growing stem plant. With high-tech (high light + CO2) tanks you should expect weekly trimming for this species. For the lush, ‘bushy’ effect commonly-seen in IAPLC tank entries, it’s important to trim often just under your desired ‘final’ height. New growth will appear as branches at the trimmed point.
It’s important to trim consistently to ‘force’ side shoots in existing stems. Rotala as a species does this readily, but will quickly shade-out shorter stems and lower leaves — you’ll need to ensure it’s pruned enough to prevent this shading action from occurring.
Since this plant grows quickly and can get bushy, be aware that it can (and nearly always does) shade lower leaves and growth. If there are slow-growing plants planted near your Rotala, be mindful of ensuring they’re not choked by its shade.
A common problem with this species is the bending of its stems — this is directly caused by poor trimming technique (or lack of trimming at all), or in some cases excessively high flow in the tank. Following the trim method described above will prevent Rotundifolia’s stems from bending and add ‘support’ for higher flow tanks.
Just like other stem plants, Rotundifolia is quite easily propagated by replanting cut stems. Doing this can quickly produce a thick, lush ‘bush’ of Rotundifolia.
common problems with rotala
Black Stems / Black spots on Stems
This happens often when you transplant Rotala from another tank — it’s mainly a result of changing water parameters, stress from shipping / planting, lack of light, or good water flow. If the higher portions of the plant are growing well, trim and replant it, then toss the blackened portions. (You don’t want that blackened portion melting in the tank — the carbon compounds, cellulose, and other matter are a trigger for algae.)
My Rotala isn’t bushy!
If there’s one thing that beginners are guilty of, it’s not trimming enough. Do a google image search for Rotala, and you’ll see thousands of spindly, thin examples of plants demonstrating poor trimming technique.
Rotala — just like other stem plants — looks much better when it’s trimmed often. Cut just above or below a node, and the plant will sprout new shoots from that point. Over time, that’ll create the “bushy” look that award-winning aquascapes make heavy use of in the background of tanks.
It seems to be dying-off under the first ‘layer’ of leaves.
While it’s great that you’re able to get the ‘bushy’ appearance, it’s also critical that you prune often enough that the ‘shading’ action of higher leaves doesn’t cause the decline of lower leaves and shorter stems. If this isn’t done, everything under that first ‘layer’ of beautifully-red leaves will be black, brown, and likely causing increased water issues from organics given-off by decaying plant matter.
There aren’t very many leaves on my rotala; it appears spindly and faded.
While there are a few possible causes, in most cases this is the direct result of inadequate lighting. Rotala will happily grow in lower-light conditions, but is particularly prone to etiolation, where the plant will increase the distance between leaf nodes on the stem in order to reach higher light as quickly as possible.
To prevent this, you can either move the light closer to the plant, or increase the amount of light provided. (As a side effect, increasing the PAR available to the plant will likely give it that classic red appearance, as well as increase its tendency to become ‘bushlike’.)