The question of whether to apply nutrients every time you water is a common dilemma for plant enthusiasts. For most common growing setups, providing a full-strength nutrient solution with every watering is not recommended. Plant nutrition, delivered through fertigation, is a powerful tool for growth, but it must be managed carefully. Understanding the distinction between water for hydration and water as a nutrient delivery vehicle is the first step toward a successful feeding schedule.
The Core Principle: Why ‘Every Time’ is Usually Too Much
The primary reason to avoid continuous, full-strength feeding is the risk of nutrient salt buildup in the growing medium. Commercial fertilizers are composed of mineral salts that dissolve in water for root absorption. When water evaporates from the medium, these mineral salts are left behind and accumulate, concentrating the solution in the root zone.
This excessive accumulation of salts creates a highly concentrated environment detrimental to plant health. The high salt concentration can draw moisture out of the roots through reverse osmosis, causing dehydration and preventing water uptake—a condition called “fertilizer burn” or “root burn.” Salt accumulation can also lead to nutrient lockout. In this scenario, the plant cannot absorb nutrients, even if they are present, because the chemical balance or pH has been severely altered by the excess salts, leading to deficiency symptoms despite overfeeding.
Key Factors Determining Your Nutrient Schedule
A single, universal feeding schedule is ineffective because a plant’s nutritional needs constantly change based on several factors. The type of growing medium is a significant variable determining feeding frequency. Soil, with its organic matter, naturally holds and slowly releases nutrients, meaning plants grown in soil generally require less frequent supplemental feeding.
In contrast, inert growing media like coco coir, rockwool, or perlite have little to no inherent nutritional content or capacity to hold nutrients. Plants in these soilless media are entirely dependent on the grower to provide all necessary nutrients, often necessitating more frequent, weaker applications. The plant’s stage of development also drastically alters its nutrient appetite. Seedlings and young plants require minimal or no external nutrients, as they are highly sensitive to salts, and a strong solution can easily cause burn.
During the vegetative stage, the plant focuses on developing foliage and stems, creating a high demand for nitrogen (N) to support vigorous green growth. When the plant transitions to flowering or fruiting, the demand for nitrogen decreases while the need for phosphorus (P) and potassium (K) increases significantly to support development. Finally, the plant’s species plays a role. “Heavy feeders” such as tomatoes and cannabis require substantially more nutrients than “light feeders” like herbs and succulents.
Practical Strategies for Nutrient Application
To prevent harmful salt buildup, the most common strategy is to alternate between feeding and watering. This is often called a “feed-water-feed” schedule, where a nutrient solution is given, followed by an application of plain, pH-balanced water. This plain water allows the plant to use residual nutrients left in the medium, helping prevent salt concentration and nutrient lockout. For plants in soil or for less experienced growers, a “feed-water-water-feed” schedule provides an even safer buffer.
Dilution and Runoff
A highly effective technique for new growers is the dilution strategy, which involves consistently using a nutrient solution at half-strength or quarter-strength of the manufacturer’s recommendation. This “less is more” approach ensures the plant receives a steady supply without the risk of sudden nutrient overload. Allowing some water to drain out of the bottom of the pot, known as runoff, is also necessary because it physically flushes away accumulated mineral salts.
Measuring Concentration (EC/PPM)
For growers seeking the highest degree of precision, measuring the nutrient concentration of the water is the most accurate method. This is done using a conductivity meter to measure the Electrical Conductivity (EC) or Parts Per Million (PPM) of the nutrient solution. EC measures the solution’s ability to conduct electricity, which directly correlates with the concentration of dissolved mineral salts. By monitoring the EC/PPM of the water going in and the runoff coming out, a grower can accurately determine if the plant is consuming nutrients and if salts are accumulating.
Monitoring Plant Health and Adjusting the Schedule
The most reliable indicator of a successful feeding schedule is the plant itself, and growers must learn to interpret visual cues. Signs of overfeeding, or nutrient toxicity, often appear as an intense, unusually dark green color in the leaves, especially when excess nitrogen is provided. A telltale sign of salt burn is the browning, yellowing, or crisping of the leaf tips and edges, sometimes accompanied by a downward curling or “clawing” of the leaves.
If these signs appear, immediately stop feeding and perform a full flush of the growing medium with several times the volume of plain, pH-balanced water to wash away excess salts. Conversely, signs of underfeeding, or nutrient deficiency, include general yellowing of the leaves (chlorosis) or stunted, slow growth. If a deficiency is suspected, slightly increase the concentration or frequency of the nutrient solution. Observing which part of the plant shows the symptom—older, lower leaves often indicate a mobile nutrient deficiency (like nitrogen), while newer growth suggests an immobile nutrient issue—can help pinpoint the missing element and guide a precise adjustment.