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Potassium Deficiency In Marijuana Plants

Potassium Deficiency In Marijuana Plants

A lack of potassium can cause a number of problems in your marijuana plant. Potassium is helpful in a huge number of your plant’s natural processes.

This is simply because potassium assists with the transport of water, which reaches every part of the plant. Every life stage that your plant goes through will require adequate amounts of potassium, and every new growth will need it too. The buds are no exception.

Potassium also helps with water respiration, photosynthesis, the strengthening and thickening of stems, and disease resistance. To put it simply, potassium is extremely important for the well-being of your plant. It is, therefore, crucial to ensure that it is receiving enough potassium to thrive.

Signs of a potassium deficiency

Signs of potassium deficiency weed

If you are growing your marijuana plants in a hydroponic system, you can rest assured that whatever symptoms you are seeing in your plants are not in fact due to a potassium deficiency. Potassium deficiencies almost never happen in plants that are growing in hydroponic systems.

They do, however, happen in planting mediums and outdoor soil every once in a while. They can even happen if your soil is especially rich in fertilizers and nutrients - and if this is the case, incorrect fertilization is probably the cause.

If your plant is lacking in potassium, it might actually be taller than the plants around it, causing the plant to stretch out and its stem to weaken. This can be deceiving, but you will realize that your plants have a problem because of the tan or brown-colored tips and edges of leaves at the bottom, as well as spots of necrotism and leaf death.

Download my free marijuana grow guide at this link for more growing tips

Left untreated, the leaves will start to show chlorotic spots, and they become patchy with red and yellow bits. The veins of these leaves will remain green, but the petioles and stems will become reddish in color.

You will also start to notice your plant’s growth slowing down, and new leaves will grow smaller in size. These symptoms occur when the deficiency has become more serious. Unlike other deficiencies, a lack of potassium is extremely mobile. It will move upward toward the biggest fan leaves, where you will be able to notice necrosis on the margins. These fan leaves will die.

In contrast, if your plant has too much potassium then it will cause the fan leaves to change color in a different way - between the veins they will be yellow or whitish in color.

Not sure if your plants have a potassium deficiency? Read the article Nutrient deficiencies in marijuana plants for a list with pictures of all deficiencies.

How to fix a potassium deficiency

Fix  potassium deficiency cannabis

Like with many other nutrient deficiencies, a lack of potassium can be avoided from the get-go by using Marijuana Booster for your plant. Marijuana Booster provides your plant with fertilization as well as a feeding schedule, so it takes out a lot of the difficult planning and decision-making that goes along with giving your plants the proper nutrients.

If you do find that your plant has become potassium deficient, you can try using a bloom fertilizer that is water-soluble and has lots of potassium. Another substance that is packed with potassium is wood ash.

Download my free marijuana grow guide at this link for more growing tips

It delivers the nutrient to your plants very effectively. If that’s inaccessible to you, you can also try liquefied kelp, potassium sulfate (wiki), potassium bicarbonate, potassium dihydrogen phosphate, or potassium silicate. For a slow-release provider of potassium, try greensand or granite dust.

Sometimes potassium isn’t being taken in correctly due there being too much calcium or nitrogen. You can check your water’s pH and flush out the system, using water with a half-dose of nutrients. You can then wait and see if your plant begins to improve.

List of marijuana plant sypmtoms

Leaf Color:
- Brown or burnt leaf edges
- Pale colored leaves
- Yellowing of the lower, older leaves
- Dark, brown spots
- Burnt leaf tips

Leaf Symptoms:
- Death of leaf tips
- Spots on leaves
- Older leaves falling off

Plant Symptoms:
- Slowed growth
- Twisted and abnormal growth
- Curling leaves (under or upward)
- Stretching - characterized by large spaces between nodes
- Plant is too tall
- Buds not getting fatter

Potassium deficiencies often resemble iron deficiencies. The tell-tale way of knowing that a potassium deficiency is a problem is by the curling leaves, the burnt edges, and leaf death.

Remember that plants with strong genetics have less change of getting sick. Make sure you buy marijuana seeds from a trusted seedbank.

Thanks for reading. Please leave comments or questions below and don't forget to download my free grow bible


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Comment Section

10 thoughts on “Potassium Deficiency In Marijuana Plants

By roger on 29 August 2016

Good info

By wayne on 24 September 2017

i start seeds in fox farm soil and i only use water only works for me

By Tim on 5 December 2017

I'm a first timer, growing 2 plants indoors in soil.
2 weeks into flowering one of them has a few leaves turning yellow and the other has some leaves with Brown spots. Not sure what to do, any suggestions would be appreciated!

By latewood_ILGM on 6 June 2018

Tim, Join our forum at: We are much better suited to help you learn from there. Thanks 🙂

By Tim on 1 June 2018

Hi I got 4 plants In not 4th week flower .3 look great as they should but one is very pale * yellow on the serations on the fingers of leaves .they all got exact same conditions help thanks

By latewood_ILGM on 6 June 2018


Join us at:
There you can add images and get help from our many friendly members and expert support staff. Happy growing 🙂

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