The Amazon Sword plant (Echinodorus species) is a popular staple in planted aquatic environments. Browning or severe yellowing (chlorosis) indicates the plant’s needs are not being met. Damaged foliage will not return to a healthy green state, requiring prompt investigation. Understanding the location and nature of the browning helps diagnose the underlying cause of stress.
Environmental Stressors: Light and CO2 Imbalances
Incorrect lighting parameters commonly cause Amazon Swords to brown or melt. When light intensity is too low, the plant cannot photosynthesize enough energy. It sacrifices older, lower leaves, causing them to turn yellow and brown while redirecting resources to newer growth.
Conversely, excessively high light can cause physical damage, similar to scorching. High light increases the plant’s demand for CO2 and nutrients; if unmet, the plant suffers. High light also fuels algae growth, which smothers leaves and blocks light absorption, leading to browning.
The photoperiod should be eight to ten hours per day to allow for rest and prevent excessive algae growth. CO2 availability plays a major role, even without supplemental injection. Insufficient carbon limits photosynthesis, slowing the plant’s ability to create sugars. Carbon starvation causes the plant to shed older foliage to conserve energy, resulting in browning.
Nutritional Causes: Deficiencies in Key Elements
The specific pattern of discoloration often points directly to a deficiency in a mobile or immobile element.
Immobile Nutrients (Iron)
Iron (Fe) is an immobile nutrient, meaning the plant cannot relocate it from old leaves to new growth. A lack of iron, necessary for chlorophyll synthesis, first manifests as chlorosis (severe yellowing) in the newest leaves. This yellowing may progress to browning at the edges.
Mobile Nutrients (Potassium)
Potassium (K) is a mobile nutrient important for water regulation. When deficient, the plant relocates it from older leaves to support new growth, causing symptoms on mature foliage first. This deficiency is characterized by pinholes, yellow spots, or necrotic (brown) spots that begin in the middle sections of the older leaves.
Mobile Nutrients (Nitrogen)
Nitrogen (N) is a foundational component required for overall growth. Since nitrogen is mobile, deficiency symptoms appear on the oldest leaves, which become uniformly pale yellow (chlorosis) as the plant reallocates nitrogen. This yellowing will eventually lead to the oldest leaves turning entirely brown and dissolving if the deficiency is not addressed.
Substrate and Root Zone Issues
Amazon Swords are heavy root feeders, deriving nutrients directly from the substrate. For optimal health, the plant requires a substrate depth of at least three inches to accommodate its extensive root system. Insufficient substrate restricts the plant’s ability to establish itself and access nutrients.
The physical nature of the substrate is important for nutrient uptake. Fine or densely compacted substrates, such as inert sand or gravel, restrict oxygen flow to the roots. This lack of oxygen can lead to root rot, which prevents the plant from absorbing nutrients, resulting in stress and leaf browning.
A plant that has outgrown its environment can signal distress. If the Amazon Sword has been in the same substrate for a long period, it may become root-bound, meaning the root mass is too dense for the current space. A constrained root system limits the plant’s capacity to absorb elements, causing the foliage to show deficiency symptoms.
Reversing the Damage: Pruning and Recovery
The first step in reversing browning is to eliminate damaged foliage, as leaves with necrotic spots will not recover. Pruning damaged leaves redirects the plant’s energy toward producing new, healthy growth. The leaf should be cut cleanly near the base of the crown using sharp scissors.
After correcting the cause, targeted nutrient delivery is necessary. Since Amazon Swords are heavy root feeders, deficiencies require placing root tabs or fertilizer spikes directly into the substrate. These tabs provide a concentrated, slow-release supply of immobile nutrients like iron, which is not easily absorbed from the water column.
Water column supplements, such as liquid fertilizers, should provide mobile elements like potassium and nitrogen, which the plant absorbs quickly. Adjusting light intensity and duration, or increasing water flow, helps the plant utilize the available nutrients. Consistent water parameters and a stable environment are needed for the plant to recover.