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How To Prevent And Treat Nutrient Lockout In Cannabis

Nutrient lockout (or nutrient lock) is caused by the pH levels when not measuring it properly, by an excessive feeding when you’re giving watering your plants with a higher dose of nutrients, if you don’t take the right care your plants will start to grow slowly, show deficiencies on the leaves and ultimately die.

1. What is nutrient lockout?

Nutrient lockout is when the necessary macro and micronutrients are present in the medium but your plant cannot absorb them because the medium is saturated or because of higher (or lower) pH levels, this it can happen in all types of mediums and your plant will start signs of nutrient deficiency.

This is a very common problem growers encounter when using a new nutrient brand and especially when using synthetic nutrients, a nutrient lockout will inhibit your plant from absorbing the nutrients it needs to develop and it can ultimately kill your plants if you don’t find out what’s wrong with them.

2. What causes nutrient lockout?

Nutrient lock can happen because of two things:

Inappropriate Ph levels

The pH level is what determines which nutrients your plant is able to absorb , that’s why it’s so important to not only check the pH of your nutrient solution but also the pH level of the medium you’re growing in.

The pH level varies depending on the medium you’re growing in and the only way to measure it is with a pH meter, so it’s essential to have one if you want to avoid problems, although you can grow cannabis without one but it will be harder to figure out what’s wrong if you encounter problems along the way.

Nutrient build-up in the medium

Because nutrients are minerals, the excess of nutrients in the medium can increase the pH level in the medium and this can inhibit nutrient absorption.

To avoid this, it’s better to use organic nutrients or really control how much and how often you feed your plants, remember than cannabis plants need a certain amount of nutrients, feeding more or less will result in nutrient deficiency.

3. How to identify nutrient lock and symptoms?

Identifying nutrient lockout can be kinda hard because the symptoms shown will be the same as when overfeeding or when there are nutrient deficiencies , like:

  • Weak plants
  • Stunted growth
  • Yellowing leaves
  • Leaves curling

To make sure your plants are suffering from nutrient lockout and not anything else, you must first check the pH level of the nutrient solution you’re feeding your plants and the medium they’re in.

You need to check both of them because sometimes the nutrient solution has the correct pH but there are nutrients accumulated in the medium, so even if you’re feeding your plants a pH nutrient solution, they won’t be able to absorb them.

There are two ways to do this and how you do it depends on the tools you have available, obviously you will need a pH meter but some of them allow you to check the soil and others don’t so you can check the soil’s pH directly or measure the run-off after watering your plants.

When measuring the run-off, the pH level of the water coming out of the pot is the pH level in the soil so if it comes up too high it means the medium has a nutrient build-up.

4. How to prevent nutrient lockout?

There’s nothing extra to do to prevent nutrient lockout other than growing with caution, with these three tips and keeping an eye for the signs your plans give you you’ll avoid any problems.

Check pH daily

Depending on the medium you’re growing in, you’ll have to check the pH daily or even multiple times a day, in hydro the roots are directly in the nutrient solution so you have to check it a couple of times a day while in soil you’ll be fine by checking the soil and the nutrient solution once a day.

If you need to adjust the pH, you can buy a pH Up or a pH Down solution at your local growshop or even adjust it naturally with lemon juice (decrease the pH) or baking soda (increase pH).

Use organic nutrients

Another good way to prevent it’s using organic nutrients, and unlike synthetic nutrients, organic nutrients make the minerals available in the medium for your plant to absorb them when they need to instead of feeding the roots directly.

If you wanna keep using synthetic ones, make sure you use good quality nutrients and always check the pH and amount of nutrients you provide in every watering, have in mind that in most cases the recommended dosage the manufacturers advise is too high, so if you don’t have a TDS meter you’ll have to decrease the dose manually.

Stages Nutrients
Seedling Water
First half of the Vegetative stage ½ dose of Veg. Nutrients
Second half of the Vegetative stage 1 dose of Veg. Nutrients
Pre-flowering stage ½ Veg. Nutes + ½ Flowering Nutes
First half of the Flowering stage ½ Flowering Nutes
Second half of Flowering Stage 1 dose of Flowering Nutrients
Ripening and Harvest Flushing (water)

You can follow the chart above to make sure you’re not overfeeding your plants, just remember that this is approximate and you should see how your plant develops to increase or decrease the nutrients.

Flush your plants

If you wanna be sure nothing happens, you can always flush between the vegetative and flowering stage although it is not obligatory but will ensure there is no excess to cause nutrient lockout when going from one stage to another.

5. How to treat nutrient lockout?

Depending on the amount of nutrients in the medium, it can take a couple of flushes to completely remove them so you will need to measure the medium until the run-off (or soil) has the correct pH, this is the only way to treat nutrient lockout, if you don’t have a pH meter then you will have to do it until your plant is back to normal.

The best pH level in your case will depend on the nutrients you’re using, your environment and the strains you’re growing but you can use this chart as a guideline.

When doing this it’s a good idea (if you are growing indoors) to decrease the humidity level in your growing space because the humidity can go up and it will stress your plants even more.

The water you’re flushing with needs to be pH’d and the right pH level will depend on the medium you’re growing in.

Medium Ph Level Range Optimal Range
Soil 5.5-7.0 6.0-6.8
Hydro and Soilless 5.5-6.5 5.8-6.0

6. In conclusion

Nutrient lockout can be caused by overfeeding but is really caused by the pH level of your solution and medium, this is a really common problem with new growers so make sure you’re feeding your plants properly.

If you’re dealing with this kind of problem and need advice or want to help us by giving tips, please leave a comment below!

Nutrient lockout inhibits your plant from absorbing the nutrients in the medium and is caused by a nutrient excess, here are some tips to prevent it.

How to Flush a Sick Cannabis Plant

Table of Contents

Why Should I Flush My Sick Marijuana Plants?

The main reason to flush your sick cannabis is to try to correct something wrong at the roots by leaching out extra nutrients or salt buildup in the soil or coco coir.

The most common reasons to flush sicks plants are…

Fix pH – The pH at the roots is several points too high or too low, causing major nutrient deficiencies

Flush Out Additives That Made Plant Sick – It’s important to flush a plant that has been watered with something that has made it sick, for example if it is losing leaves because it was recently watered with a pesticide, nutrient or supplement that was too strong.

Leach Out Time-Release Nutrients – If transplanting isn’t an option, sometimes a grower will flush a plant that is being grown in soil with “time release” nutrients (like Miracle-Gro soil). This idea is to try to leach out extra nutrients (specifically nitrogen) before the flowering stage begins. Too much nitrogen in the flowering stage can give buds a “green” taste as well as actually prevent buds from getting as big as they normally would. Since time-release soils slowly releases nitrogen for months it’s important to flush that out before your plant starts making buds.

If your cannabis plant gets sick the day after you add a new supplement for the first time, you should probably flush your plant to “start fresh” at the roots

Which Growers Should Flush Their Plants?

Flushing sick plants is for…

  • Soil
  • Coco coir
  • Other soilless mediums

Flushing sick plants is NOT for…

  • Hydroponic or DWC grow setups – if you have a nutrient or pH problem, just change the reservoir so it has exactly what you want

How to Prevent the Need to Flush Your Plants

When hand-watering plants, always give plain water every other watering

Always start with 1/2 strength nutrients, and only increase nutrient dose if the overall plant is starting to look pale or lime green. Learn more about nutrient deficiencies. It’s also a good idea to start any pesticides or supplements at half strength until you see how your plant reacts.

Always check and adjust the pH of your plants every single time you give them water. Even if only giving plain water. Maintaining the pH is the #1 way to prevent nutrient deficiencies, and simply by doing this you’ll dramatically reduce the chance you’ll even need to flush (pH being too high or too low is the main reason to flush plants).

When plants are sick, try moving the grow light up a few inches or even a foot. This will help your plant recover more effectively from many nutrient problems, whether you end up flushing the plants or not.

Try to prevent nutrients problems before they happen so you never need to flush!

How to Flush Sick Cannabis Plants

Make up water with low levels of nutrients (1/4 strength or seedling dose). You want to take out the bad and replace with the good.

Give 3x the pot size – Use enough water so that you’re giving the plant 3x as much water as the volume of the pot. It may take a little while. Remove all runoff water immediately, you don’t want your plant to suck the bad stuff back up!

Give regular strength nutrients at the end – Make up one last batch of nutrient water at regular strength, and give this to your plants. You are replacing what you took out with what you want to be there – fresh, pH’ed nutrient water!

Make sure there is a fan blowing over the top of the growing medium to help it dry out so plants don’t get as droopy from being overwatered. There should be plenty of air circulation in the grow space, with access to lots of fresh air.

Raise your grow lights up a few inches while your plant is recovering. Your plant definitely needs plenty of light, but you don’t want to make it work too hard during the recovery period.

Wait a few days for improvement – Although your plant may get droopy at first, you should start to see improvement within a few days. Try not to water it again until the top inch is starting to dry. It’s not recommended to flush a plant two times in a row. After the first flush you should have flushed out what was hurting the plant in the soil. At this point, it’s time to give your plants some TLC while you get things back on track.

How to Fix Incorrect pH Without Flushing

1.) Determine your target pH

  • Soil: 6-7 pH
  • Coco: 5.5-6.5 pH

2.) Collect runoff – Give your water at the correct pH, and collect runoff water out the bottom.

3.) Is the pH too high or low? If the pH is higher or lower than the correct range, don’t panic! At the very least you’re already giving your water at the correct pH from on top. That will help the plant stay healthy while you fix whatever is going on at the roots.

4.) Start correcting the pH the next time you water your plants. If you already have major nutrient problems, you might consider flushing as stated above. But if you don’t see problems yet, or if you only see just a little bit of leaf discoloration or yellowing, there’s no need to flush. Flushing is very stressful for plants and may prevent them from recovering as fast as they could, so it should be avoided if possible.

Most of the time, if your runoff pH was too high or too low, it’s better to wait until your next watering to start correcting it.

5.) Always give water in the correct pH range, but at the opposite end. Next time you water your plants give water in the correct range, but at the opposite end of the range to start trying to get it to move in the other direction.

If your runoff water is coming out at 4.5 pH, it means you should water your plants at the high end of your desired pH range. So for soil you would water your plants at 7.0 pH, and with coco you’d water your plants at 6.5 pH.

This ensures that your roots are getting some amount of nutrient water at the correct pH, while also starting to leach out whatever is in the growing medium that’s dragging the pH down.

Eventually, your pH is going to start coming out the bottom of the plant in the right pH range, even if it takes a few weeks.

I’ve found that correcting the pH this way seems to stop most nutrient problems within just a few days, while preventing your plant from getting stressed from a true “flush.”

I wish I had known this before I started growing 🙂 I’ve done too many unnecessary flushes and unintentionally stressed out my plants!

How to Flush a Sick Cannabis Plant Table of Contents Why Should I Flush My Sick Marijuana Plants? The main reason to flush your sick cannabis is to try to correct something wrong at the ]]>