Homegrown StoreBlogCannabis CultivationHow To Avoid And Solve Nutrient Lockout In Cannabis

How To Avoid And Solve Nutrient Lockout In Cannabis

nutrients lockout freature

Is your crop looking discolored and fragile despite your diligent waterings and feedings? You might be dealing with nutrient lockout.

This cannabis cultivation pitfall resembles a deficiency but occurs for a different reason and requires a unique treatment plan. Read on to learn about lockout symptoms, causes, and solutions and help your plants become green and healthy again.

Let’s begin.

nutrients lockout

What is a nutrient lockout, and how does it occur?

Weed plant deficiencies occur when the growing medium doesn’t contain enough nutrients to sustain development, resulting in small and malnourished crops. The issue we’re discussing has the same consequences but doesn’t stem from a lack of food.

What is a nutrient lockout, and why does it happen?

This plant health problem occurs when your crop is incapable of absorbing nutrients due to the conditions in the medium. You provide plenty of food, but it sits around the weed root system without nourishing the plant.

A cannabis lockout can happen in all setups, but it occurs most commonly in soil. How does it look?

nutrient deficiency - Dying cannabis plant with incomplete marijuana leaves

Signs of a nutrient lockout in weed

A lockout happens beneath ground level, so it’s not instantly observable. You can only notice it through crop symptoms and then diagnose it by checking your medium and feeding practices.

Here are the common signs of a nutrient lockout in weed:

Unlike pest issues, cannabis nutrient lockout doesn’t induce any particular symptom that makes you say a-ha! Instead, telltale signs vary between growth stages and the minerals in scarcity. Still, if you see overall signs of ill health, you should look into the potential causes.

Cannabis Calcium Deficiency

Common causes of a nutrient lockout

Nutrient lockout is what it says on the tin. The minerals can’t nourish your plants due to chemical reactions between the fertilizer, growing medium, and roots.

What causes nutrient lockout? Here are two common reasons why it happens:

Improper pH levels

The root system requires the right mineral amounts and acidity levels. The latter is often behind nutrient lockout signs when thrown out of balance.

The importance of cannabis soil pH is utmost since it affects the availability of the surrounding nutrients. The sweet spot for growing plants is 5.5–6.3, although crops tolerate anything in the 5.0–7.0 range.

pH lockout in cannabis occurs when the acidity drifts outside the optimal range. As a result, the crop absorbs some nutrients but not others. The particular deficiency depends on the mineral’s chemical properties.

Check this small-scale nutrient lockout chart to see what gets locked out at various pH values:

  • Very/slightly acidic: Magnesium, calcium, molybdenum, and phosphorus lockout
  • Slightly/very alkaline: Iron, copper, and zinc lockout

Your medium might be too alkaline or acidic due to its natural properties, fertilizer, or the kind of water for weed you choose.

pH for cannabis


Are you generously feeding your crops and still seeing nutrient lockout symptoms? Your eagerness to provide fertilizers might be the issue.

As the plants absorb compounds, the surrounding soil accumulates excess nutrient salts. These chemicals interact with your plants and mineral solutions when they build up too much.

Excess nutrients bond or, more commonly, become incompatible. Due to this chemical reaction, a buildup might make minerals unavailable for absorption.

How to deal with a nutrient lockout in cannabis

After diagnosing a nutrient lockout, it’s time to resolve it. Adding more fertilizer isn’t likely to fix the issue, but these two solutions are:

Check your feeding journal

Novice growers are often worried about deficiencies and trigger a cannabis nutrient lockout by overdoing it with fertilizer. Start the treatment plan by ensuring you’re dosing the minerals properly.

There’s no hard and fast rule on how often to feed the crops, so heed the manufacturer’s instructions. Generally, growers provide nutrients once a week or with every third watering.

Dosing is less straightforward than frequency. Start young plants with half the recommended intake and increase it gradually till late vegging. Fix a nutrient lockout during flowering by cutting out fertilizer several weeks before harvest.

Feeding cannabis plants


How do you fix nutrient lockout if your feeding chart and solution are perfect? By adjusting the pH levels to facilitate mineral uptake.

Flushing is a straightforward process of rinsing your medium with pH-neutral water. Doing so restores the optimal balance between acidity and alkalinity.

If treating cannabis nutrient lockout in soil, pour fresh water into the pot and let it drain at the bottom. Use approximately four times the container volume and hold off the next shower until the medium dries.

If working with hydro, clean the reservoir and fill it with plain water. Let it circulate for 24 hours.

The excess water breaks down the salt buildup and relieves the pH lockout in cannabis. Once the process is complete, measure the acidity and supply the appropriate nutrients.

nutrient lockout evolution in cannabis plants
Nutrient lockout progression in cannabis plants

4 Ways to prevent cannabis nutrient lockout

Nutrient lockout in weed is preventable with good gardening practices. Nip the issue in the bud and never let quality genetics from our cannabis seed bank go to waste by:

  • Regularly checking pH levels. A pH lockout in weed isn’t rare, so get in the habit of utilizing your acidity meter regularly. Check the water, soil, and runoff pH weekly to catch imbalances at the start.
  • Performing routine flushes. Regularly ridding the medium of excess salt supports overall plant health. Do it once between vegging and flowering and again halfway through the blooming stage.
  • Using organic nutrients. Salt buildup dehydrates the plants and causes the dreaded signs of nutrient lockout. Organic cannabis fertilizers don’t eliminate this issue, but they reduce it.
  • Avoiding crop stress. Slowly change the feed regimen and train with care. Take a week to switch between 18/6 and 12/12 light schedules gradually. Even sturdy weed strains need time to adjust to new circumstances and could stop absorbing nutes if shocked.

With these four practices, you might still see marijuana plants with nutrient lockout, but the risk plummets. They also improve yields, so your garden can only benefit from them.

Unlock the nutrient lockout

Nutrient lockout in cannabis is a frequent issue for growers of all levels. Luckily, it’s also easy to resolve if you know where to look.

Check the soil before you reach for more fertilizer to address a deficiency that isn’t there. That way, you won’t waste money and exacerbate the trouble. Then, follow our tips to unlock the nutrients and watch your crops flourish.

With this complete guide, nothing stops you from producing top-tier buds. Head to our shop to get premium weed seeds and get impressive yields.

About the author: Parker Curtis

Parker Curtis has around a decade of cannabis-growing experience, specialising in soil-less and hydro grows. He’s mastering outdoor, greenhouse, and indoor grows.

Was this article helpful?