Plants on Lockdown

By Lacey Macri
Published: October 1, 2016 | Last updated: April 23, 2021 02:16:00
Key Takeaways

Nutrient lockout is a common problem many gardeners encounter and is often misdiagnosed. Learn how to distinguish the symptoms and causes of nutrient lockout, and pick up some tips on how to avoid it in the future.

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Nutrient lockout occurs when plants are unable to absorb the basic nutrients needed to remain healthy. This typically happens as a result of a chemical reaction that takes place between the nutrient solution, the grow media and the plant itself.


Commonly confused with a nutrient deficiency, nutrient lockout cannot be cured by adding more nutrients. Although nutrient lockout may result in deficiencies of certain nutrients, the causes must first be treated before more nutrients can effectively be absorbed.

If your plants are experiencing nutrient lockout, you may notice stunted growth, and the foliage will turn yellow and become limp and lifeless.


Your plants may also experience some amount of leaf burn.

Double-check your EC, TDS and pH to rule out a nutrient deficiency as the cause of such symptoms. There are several main reasons why nutrient lockout may arise.

Salt Buildup in Plants

Healthy plants take up nutrients through a process called osmosis. Osmosis in plants occurs when the water concentration outside the roots is higher than it is inside the roots, so the plant absorbs water to equalize the osmotic pressure between the two sides.


Over time, the nutrients you add to your system may collect in unwanted areas such as your grow media.

Nutrient lockout is commonly caused by a buildup in salts from an excess of nutrients. If this happens, excess nutrients may either bond together, or become incompatible at certain levels, ultimately making them unavailable to the plant.


Water with a high TDS number may also contribute to excessive salt buildup, which is why it is important to be aware of the nature of the input water you use so you can adjust accordingly.

If you are growing hydroponically, emptying your reservoir and running a flushing agent mixed with fresh water through your entire system will help break down the salt buildup.

It may be necessary to irrigate your plants with this solution for a few days until the nutrient lockout has resolved itself. One of the safest and most effective flushing agents on the market is hypochlorous acid.

Available through several brands in the industry, hypochlorous acid can be used alone as a flushing agent, or as part of your regular feed schedule to help prevent salt buildup, reducing the likelihood of experiencing nutrient lockout down the road.

Hydroponic Nutrient Quality

As indicated by its title, nutrient lockout is largely dependent on the quality of the nutrients used. Using a nutrient program that is broken down into two or more parts is the best way to help prevent nutrient lockout, as plants’ nutrient demands change through their natural course of development. Whether you are using a one-part or a four-part nutrient formula, the total volume of fertilizers used, along with the responses from your plants, must be taken into consideration when determining the value and efficacy of the products.

How to Avoid a pH Imbalance in Your Hydroponic Garden

One of the most important factors to monitor throughout the growing process is pH. Water with a pH that is too high can encourage algae growth, while water with a low pH can scorch plants.

Generally speaking, the aim in hydroponics is to maintain a pH that is slightly more acidic than neutral, within the range of 5.5-6.5.

The reason for this range is that each nutrient has an optimal pH range for the highest level of absorption to occur depending on nutrient demands distinguished by crop type and their stage of development.

Determining your target pH while keeping these factors in mind will help prevent the risk of nutrient lockout.

There are many different pH buffering solutions available on the market that can be added directly to your reservoir to adjust pH if it is unexpectedly thrown off.

It is best to use nutrients and supplements with a neutral or balanced pH to help prevent nutrient lockout caused by improper pH levels in the first place. Using RO (reverse osmosis) water is another good way to help prevent problems associated with nutrient lockout.

As always, preventative measures tend to work best for avoiding issues. As a basic rule of green thumb, though, the most effective way to treat plants experiencing nutrient lockout is to flush and refresh your entire system.

Starting with RO water, using high-quality, pH-balanced nutrients and supplements, and flushing regularly will all help encourage a healthy environment for your plants to grow, eliminating a lot of the causes of nutrient lockout.


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Written by Lacey Macri

Profile Picture of Lacey Macri
Lacey Macri works as head of sales at CleanGrow, focusing her time on business development within the company. She received a bachelor’s degree in communications and psychology from the University of California, Davis, in 2011, where she worked at the California Aggie student newspaper on campus.

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