The 10 most common reasons aquatic plants die
By Aram Schneider Published Updated
Translated from German with AI assistance and reviewed by our editors.
Why aquarium plants grow poorly or even die off completely can have various reasons. We have summarized the 10 most important causes for you.
1. Adjustment problems after planting
We all know it: the aquatic plants are freshly bought and look good at first. You then plant them, and after a few days the aquarium plants get worse and worse. Individual leaves or even whole parts of the plant die off. The cause is often that the plants still have to adjust. In the sales forms of potted plants and in-vitro, the plants are still in the emersed state, that is, in their above-water form. For the submersed form (underwater form), an adjustment takes place that changes the plant's appearance, above all leaf shape and color. It can then indeed happen that emersed plant parts die off or are shed.
This is not a big reason to worry, however. To a certain extent this process is completely normal. As long as you above all provide good growth conditions in the form of a sufficient nutrient supply, the aquatic plants can form healthy new shoots from the rhizomes or stems that are adapted to life underwater. You can find further tips on this topic here.
2. CO2 deficiency
Especially in a well-equipped planted aquarium, a sudden lack of carbon dioxide is one of the most common causes of poor growth of aquatic plants, often in combination with the appearance of algae. Often there is a technical problem here: the bottle has run empty, the diffuser has become dirty or one of the CO2 components has a defect. Therefore service and check your CO2 system regularly so that it can always reliably supply the plants with carbon. A CO2 drop checker and bubble counter help you monitor the carbon dioxide supply in the aquarium well.
3. NO3 deficiency
Deficiency symptoms in aquatic plants can arise from various nutrient deficits. Besides insufficient CO2, however, a nitrogen deficiency in a planted aquarium is among the top 3 reasons for poor plant growth. This applies in particular when many fast-growing plant species are present and at the same time intense lighting, additional carbon supply and liquid fertilization are used. The plants are actually supplied fully and at first grow very well. A deficiency often arises when the plant mass, and with it consumption, keeps increasing. An undersupply then often occurs with the nutrient that is needed in particularly large amounts. In most cases this is nitrogen (NO3). This shows up, among other things, in stagnating growth, yellow leaves and also the appearance of algae in the aquarium.
Nitrate can, however, be determined quite easily with a suitable water test and adjusted very specifically in the fertilization using pure nitrogen fertilizer.
4. Other nutrient deficiencies
Besides CO2 and NO3, other nutrients can of course also be the cause of deficiencies through undersupply. From experience, however, they do not occur as often as with nitrogen and carbon. That is why we have listed these two parameters separately. Other important nutrient elements for aquatic plants are iron (Fe), phosphate (PO4), potassium (K) and magnesium (Mg). In addition, plants need various trace elements, which are generally contained in a complete iron fertilizer. Potassium, magnesium and phosphate are among the so-called macronutrients. In some cases, certain damage patterns or growth patterns with deficiency symptoms can also be assigned to specific nutrients. To learn more about this, we recommend reading our article "Deficiency symptoms in aquatic plants".
5. Algae growth
Another factor that can prevent plants from growing healthily is algae growth. With heavy algae infestation of the plant leaves, less and less light reaches them, which makes photosynthesis harder. Algae species that spread over a large area, such as cyanobacteria and fuzz algae (see picture), but also black beard algae, are a problem here. The plant's metabolism is disturbed by the algae overgrowth, so that it becomes weaker and weaker over time and dies. It is therefore important to react early and eliminate the algae. The causes of the algae growth should also be eliminated. Mostly there is a nutrient imbalance here. For suitable advice, you can browse our algae guide.
6. Over-acidification
Dying aquatic plants that fall apart into mush are often attributable to fresh soil during the cycling phase. Its strong cation exchange capacity makes the water very soft and acidic, which weakens sensitive species. A similar effect can also occur when only RO water without hardening is used or when too few water changes take place in the first weeks.
Aquarium plants, but also the aquarium inhabitants, need enough minerals to grow healthily. You should therefore not let the general hardness drop below approx. 6 °dGH. In addition, at least a slight carbonate hardness helps to buffer the pH value. This prevents a pH crash. Especially during the cycling phase, you should therefore counter-buffer a little with enough water changes and/or the use of a hardening salt to minimize the risk of plants dying off through over-acidification.
7. Feeding damage
Do you find strange holes in the leaves or frayed leaves? Then it may well be feeding damage from plant-eating animals. These include, for example, various catfish, shrimp, crayfish, snails, but also garras or Chinese algae eaters. Often the feeding damage is not recognized as such at all. Holes in leaves are often diagnosed as a deficiency symptom in the sense of a potassium deficiency. That is not always the case, however.
A remedy for feeding damage is sufficient feeding of plant-based food for the animals. Leaves, for example, are an ideal food supplement for shrimp and crayfish. Appropriately prepared vegetables also appeal to plant-eating aquarium inhabitants. You can find more info on this in this article.
8. Too much plant glue
Plants can also be damaged if too much plant glue is used. This is a cause that of course mainly affects plants that are attached to hardscape with glue. These include above all mosses but also epiphytes such as ferns, Anubias or Bucephalandra. A gel-type plant glue based on cyanoacrylate should be used as a suitable glue. The amount to be used is very decisive, however. Here you should really work only drop by drop, especially with mosses. It is enough to apply the glue at points and not over the whole surface. Too much glue causes plant parts that come into contact with it to die and also leaves quite conspicuous white spots on the hardscape.
9. Transport damage
Especially if you have ordered aquatic plants on the internet, something can go wrong during transport under certain circumstances. As a precaution, we at Aquasabi only ship healthy-looking aquarium plants, which are also checked once more before shipping. The plants are packed and cushioned accordingly well to suit the weather and the rest of the order. If necessary, we also ship plants and other accessories in separate packages, e.g. if there is a risk that heavy items such as stones or substrate could damage the plants too much. We do everything so that your aquatic plants arrive at your home intact.
Unfortunately, something can also go wrong on the way, and the plants can be damaged as a result. This includes, for example, physical damage such as broken or crushed stems and leaves, for instance through rough handling during transport. Drying-out damage in the form of dried-up or wilted leaves can occur if delivery takes too long and the plants do not get enough moisture for a longer time.
As a first-aid measure, we put a plant flyer in our packages. In an emergency, follow the measures described there and check the plants immediately upon receipt. If you receive plants damaged by us, please take photos and contact us by email. We will then surely find a good solution for your problem.
10. Frost damage
So-called frost damage is one kind of transport damage. We have listed it separately, however, because it is a special topic. Frost damage can, for timing reasons, only occur in winter and is caused during transport by temperatures that are too cold. In practice, however, this phenomenon occurs much more rarely than is often assumed. At Aquasabi, we make sure the packaging suits the weather for winter shipping, if necessary also with a heat pack. In addition, most aquatic plants tolerate a cool temperature slightly above freezing quite well.
If frost damage does occur, it shows, generally speaking, in wilted-looking leaves and significantly reduced vitality. Their healthy coloring is often lost across the whole plant - the once vigorous green fades and gives way to grayish, brownish or dark green tones. With partial frost damage, the discolorations often appear only in certain areas of the leaf surface. Depending on the species, however, frost damage can also develop differently in individual cases.
Would you like to learn more about the topic of frost damage? We have a separate article on it here.