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Why Your Organic Cannabis Plants Need Potassium

By Michelle Pugle

Your organic cannabis plants need potassium to survive and thrive. Potassium (K) is a staple macronutrient in plant cultivation and is responsible for healthy growth and reproduction. 

According to Gardening Know How, potassium is absorbed from the soil for these specific benefits: 

  • Faster growth 
  • Improved drought resistance
  • Disease prevention
  • Pest control
  • Higher yields
  • Stronger growth

Without adequate amounts, your organic cannabis plants will be fragile and their leaves may turn yellow or brown and begin to curl or look burnt. By this time, they are deficient in one of a plant’s core requirements for healthy living. 

What you need to know about potassium deficiency

Yes, it’s bad. No, tossing composted banana peels in your plant pots or beds won’t solve all your problems; it could actually make them worse. 

As always, make sure you do a soil test before applying any nutrients, including something as seemingly harmless as potassium from natural sources. Excess potassium leads to soil toxicity that needs an intervention of its own. 

Safely adding potassium to soil

If your soil test says you need potassium, make sure you add it from organic origins. Working on fixing the underlying ecosystem issue over several seasons is the most sustainable strategy. This means incorporating ingredients like compost, manure, potash, bone meal, wood ash, and commercial organic fertilizers, which don’t drown the roots in nutrients like water soluble synthetic fertilizers. 

Organic fertilizers can, however, still burn your plants if you’re not careful with your measuring. For example, overapplication of wood ash can burn roots. 

Remember that no matter the source, it’s always advised you add fertilizers in a raised circle around the plant base. At the very least, don’t let the nutrients touch the roots directly. Let your roots go searching for the nutrients so they grow stronger over the time the nutrients are slow-released. 

At the end of the season, you can rake the nutrient mounds into the rest of your gardening space to help with your soil’s fertility. If you were fertilizing in pots, you can add the soil to your compost or garden beds. 

Should You Be Concerned About Potassium in Cannabis Plants? 

While it’s true that every plant needs a supply of potassium to survive and thrive, potassium deficiencies or toxicities aren’t common in cannabis plants.

“Generally, cannabis only requires relatively small amounts of potassium early on, and will start pulling much more significant amounts of it when it enters the flowering phase,” says the Grower’s Network. 

“Our resident growing expert says that you’ll likely start seeing potassium deficiencies or toxicities around week 3 or 4 of flowering.” Pay particular attention to signs at this time to prevent problems, but remember, always do a soil test before applying nutrients.