Fish fertilizer, also known as fish emulsion or liquid fish, is a popular organic nutrient source derived from fish byproducts. This liquid amendment is rich in nitrogen, supporting vibrant foliage growth and overall plant health. Using this product indoors requires specific knowledge of the product type, dilution, and application techniques to manage common challenges. This guide provides the practical steps necessary to successfully incorporate this effective fertilizer into your houseplant care routine.
Understanding Different Fish Fertilizer Products
When selecting a product for indoor application, you will encounter two main types: fish emulsion and hydrolyzed fish fertilizer. Fish emulsion is produced by cooking the fish parts, resulting in a thick, concentrated liquid with a notably strong odor. The cooking process can sometimes reduce the availability of certain heat-sensitive micronutrients.
Hydrolyzed fish fertilizer is created using a cold-processing method that employs enzymes to break down the fish proteins. This enzymatic process retains more of the natural oils, amino acids, and growth-promoting substances found in the fish. Hydrolyzed products are often considered superior for indoor use because they typically have a cleaner, less offensive odor that dissipates more quickly. Both types offer a balanced mix of macro and micronutrients that feed the soil’s microbial life, providing a gentler, more sustained feeding compared to synthetic options.
Proper Dilution and Preparation Ratios
Because fish fertilizer concentrates are potent, they must be properly diluted before being applied to houseplants to prevent root damage. The general rule for indoor plants is to start with a much weaker concentration than what is recommended for garden use. Concentrated products can cause fertilizer burn, which manifests as browning leaf edges or stunted growth, when applied directly to the soil.
A safe starting point for most houseplants is to mix one tablespoon of the concentrated product for every gallon of water. This ratio represents half to quarter strength of the standard outdoor recommendation, reducing the risk of over-fertilization. Always shake the concentrated bottle well before measuring, as the components can separate during storage. Mixing the fertilizer into lukewarm water helps the liquid blend more easily and is gentler on the plant roots. The prepared solution should be used immediately, as the organic components can begin to decompose quickly, intensifying the odor.
Application Methods and Feeding Schedules
The most common and effective method for applying fish fertilizer to potted plants is the soil drench. This involves pouring the diluted mixture slowly over the soil surface until it begins to drain out of the pot’s drainage holes. This ensures that the entire root zone receives the nutrients and helps flush out any accumulating mineral salts. It is important to always water the plant with plain water first if the soil is completely dry, preventing the fertilizer solution from shocking thirsty roots.
Foliar feeding involves lightly spraying the diluted solution onto the leaves for quick absorption. This technique is only suitable for plants with smooth leaves, as plants with fuzzy or pubescent leaves can trap moisture, potentially leading to fungal issues. Indoor plants require less frequent feeding than those grown outside, typically benefiting from an application once every three to four weeks during their active growing season in the spring and summer. Feeding should be reduced or stopped entirely throughout the winter months when most houseplants enter a period of dormancy.
Controlling Odor and Indoor Pests
The characteristic odor of fish fertilizer is the primary concern for indoor growers, but there are practical ways to manage it. Using a hydrolyzed product, which tends to smell less than a traditional emulsion, is the best preventative measure. You can reduce the lingering smell by taking your plants to a sink, shower, or even outdoors to apply the fertilizer solution. Allow the excess water to fully drain before returning the plants to their regular location, which helps to ventilate the initial strong aroma.
The organic residue left on the soil surface can sometimes attract fungus gnats after application. To deter these insects, consider covering the top layer of soil with a thin barrier of sand or food-grade diatomaceous earth immediately after fertilizing. Proper storage of the unused, concentrated fertilizer is important; keep the sealed container in a cool, dark place away from direct sunlight. This helps maintain its quality and prevents an increase in odor-causing decomposition.