Liquid fertilizer is a versatile form of fertilizer that can be applied to the roots and leaves of a plant. Liquid fertilizer makes nutrients immediately available to your plants, as it’s easier for them to absorb the nutrients that are already dissolved in water. However, that doesn’t mean you shouldn’t be cautious when using it.
It’s possible to use too much liquid fertilizer, which can lead to fertilizer burn. Liquid fertilizer is diluted, but it still contains salts like any other fertilizer. If you apply too much, the salt concentration will be high enough to draw water out of plant tissue, damaging your plants.
In this article, I’ll explain what will happen to your plants if you use too much liquid fertilizer. I will also give you some information about liquid fertilizers and how you can apply them correctly.
The Effects of Using Too Much Fertilizer
Liquid fertilizer may be organic or inorganic. It’s a convenient way to fertilize your plants, making nutrients easily available to your plants. The nutrients are already in the water, which is how plants uptake nutrients.
If you use too much liquid fertilizer, your plants will start wilting, yellowing, browning, and eventually dying. Too much fertilizer, even liquid fertilizer, leads to fertilizer burn that dehydrates the plants. Affected roots and leaves cannot be saved, and if enough are killed, the plant dies.
Liquid fertilizer is typically made by diluting concentrated fertilizer. You can also make your own liquid fertilizer by steeping your granules or plant food spikes in water, though this is not the best use of these types of fertilizers.
Because liquid fertilizers are made by diluting concentrated fertilizers, it is easy to think that you’re using less than you actually are. This effect is strengthened by the fact that liquid fertilizers are typically used a little at a time and more frequently.
However, all inorganic fertilizers contain mineral salts that accumulate in the soil with every use. If you use too much at once, your plants will not be able to absorb all the nutrients.
Over time, the salt build-up will draw water out of your plant, leading to fertilizer burn. This will affect your plant’s growth, and set back yield times.
An Overview of Liquid Fertilizers
Liquid fertilizer refers to organic or inorganic fertilizers that are suspended, dissolved, or diluted in water. Both solid and liquid fertilizers need to be diluted in water before application, as plants need water to absorb nutrients.
Supplying plant nutrients in a liquid form also ensures that mineral salts in the fertilizers do not cause dehydration in the plants, assuming the right amount of fertilizer is applied.
Liquid fertilizers are used across all kinds of plants, shrubs, and lawns. They are particularly useful for fruiting plants and vegetables. Liquid fertilizers supply immediate nutrients to flowering and fruiting plants, which use large amounts of macro and micronutrients in the growing season.
These fertilizers are also useful as starting solutions. They can be diluted down and used to supply nutrients to seedlings in the early days of growth.
While slow-release fertilizer is a good idea to prevent root burn, a starting solution will ensure that the plants receive the nutrients when they need them in a form that will not burn their developing root systems.
Types: Organic and Inorganic
The two main types of liquid fertilizers.
Organic fertilizers are made from manure, compost, kitchen scraps and other waste, plant waste, and other sources, such as bone meal. These are naturally occurring and not heavily processed without fixed NPK ratios. Because of this, they don’t lead to fertilizer burn.
Inorganic fertilizers are made up of mineral salts with precise NPK ratios. Unlike organic fertilizers, these work instantly, but can lead to fertilizer burn if used incorrectly.
Among these two main types, there are several different kinds of liquid fertilizers depending on the ratios of nitrogen, phosphorus, and potassium, their overall composition, and how they’re made.
Organic fertilizers are affordable and better for the environment, but they work slowly. Inorganic fertilizers are more precise and effective at ensuring higher yields in your plants.
The type of fertilizer you choose will depend on what you need from your garden. If you have the luxury of time and you’re not reliant on your fruit yields, then you can use organic liquid fertilizers and eliminate any chance of fertilizer burn.
Considerations for Applying Liquid Fertilizers to Your Plants
There are several ways of applying liquid fertilizers to your plants.
The key is to consider a few relevant factors to ensure that you’re using the right amount and kind of fertilizer for your plants:
Nutrients
The first thing to do, as with all fertilizers, is to assess what nutrients your plants need instead of applying a generalized fertilizer. Applying too much of the wrong nutrients can also lead to fertilizer burn. You can mix two or more single-nutrient fertilizers in the ratios you need or purchase a premixed blend.
Quantity
It is vital that you only apply as much as or less than the quantity specified on the packaging. When in doubt, dilute the fertilizer further—you can always add more later.
As a general rule of thumb, make it more diluted for plants with weak or new root systems. Inorganic liquid fertilizers should only be applied during the growing season, while organic fertilizers can be applied year-round.
Irrigation
Water is what ensures that the nutrients you supply actually get absorbed by the plants. Water your plants thoroughly a day before fertilizing them.
After application, wait a few days for the fertilizer to be absorbed or dry completely. Then, water your plants again to ensure there’s no runoff.
Timing
Timing your fertilizer application is very important. Plants need extra nutrients in their growing season, which is usually spring.
Time your fertilizer so that you fertilize your plants after it rains rather than before. This prevents the rain from washing your fertilizer away.
Application Method
While there are many different ways in which you can apply liquid fertilizers to your plants, the main differences are where you apply them.
You can apply fertilizer to the soil or directly onto the leaves. Applying fertilizers to the leaves makes nutrients more available to your plants but can also lead to leaf scorch.
Best Application Methods
The goal of applying fertilizer is to support root development, which ensures that your plants will grow up healthy and strong. Strong roots also lead to better overall yields.
The best way to apply liquid fertilizer for root growth is through concentrated spoke injectors, foliar applicators, or fertigation. These should be applied to where your plants have a high density of fine roots to ensure maximum nutrient absorption.
Irrigate the soil for a while before application so the fertilizer is properly dispersed.
Injectors
Injectors are the most common way of applying liquid fertilizer to the soil. They’re convenient and effective. They apply the fertilizer under the surface, which allows it to reach the finer roots of the plants.
Surface applicators are better for plants with root systems that spread out wide and shallow.
Fertigation
Fertigation is a way to supply fertilizers through the irrigation channels, fertilizing and irrigating your plants at the same time. This is one of the best ways to apply liquid fertilizer without burning your plants, as the fertilizer will be supplied together with the plant’s water requirements.
The additional dilution should prevent plant desiccation. Fertigation will also ensure that you only use a set amount of fertilizer at a time, which will stop you from using too much liquid fertilizer at once.
Foliar Application
Foliar application of liquid fertilizer is great for mitigating mid-season nutrient deficiencies in plants. It ensures that the nutrients are immediately present in the leaves. However, these applications need to be heavily diluted and don’t last very long.
Applying too much liquid fertilizer to foliage can lead to leaf scorch. Even using appropriate amounts can lead to burns if the days are especially hot and dry or if the fertilizer accidentally falls on plants that don’t need it.
If it rains immediately after you’ve applied your fertilizer, it will get washed away, possibly into groundwater or freshwater bodies, leading to pollution.
Irrigating before you apply your fertilizer is crucial to help the fertilizer disperse deeper into the ground, to your plants’ deepest and finest roots. Never apply fertilizer to completely dry ground, and avoid fertilizing in hot months without irrigation. Well-irrigated soil will protect your plants from fertilizer burn even if you accidentally use too much liquid fertilizer.
Final Thoughts
It is possible to use too much liquid fertilizer, especially due to the fact that the dilution of the fertilizer leads people to believe that they are using less than they actually are.
Overfertilization by inorganic liquid fertilizer will lead to a salt build-up that will dehydrate your plants, causing fertilizer burn. It is important to dilute your fertilizer heavily before applying it to the soil and irrigate your soil well to protect your plants from any accidental overuse of liquid fertilizer.
