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Time to start flushing

captain

Member
Joined
Apr 5, 2023
Messages
32
This is now the time of year in California for outdoor growers to switch from fertilizers to ph balanced water to flush outdoor plants from the less than ideal tastes that remain in the plants as a result of fertilization. I have been using compost tea throughout the growth of the plants. My tap water's ph is ~7.24 so I need to adjust it down to closer to 6.2 so that the roots remain happy. I use a diluted amount of citric acid to lower my natural ph to the 6.2-6.8 range recommended for flushing cannabis plants. Since I'm in the bay area and flushing is recommended for the last 2 weeks of growth and I have been growing outdoors for over 10 years, my plants seem to demand harvesting either the last week of September or the first week of October, so we're getting close.

The flushing process results in a better, cleaner, and more natural tasting flavors that can be spoiled in non flushed plants by residual nutrients. Here are the recommended ph levels for flushing your plants, courtesy of ChatGPT:

“Plain pH-balanced water” = just clean water, adjusted to the proper pH range for your medium.
  • Soil: 6.2–6.8
  • Coco: 5.8–6.2
  • Hydro: 5.5–6.0
Hope this helps new growers to attain a more flavorful harvest.

Happy Growing!

 
This is now the time of year in California for outdoor growers to switch from fertilizers to ph balanced water to flush outdoor plants from the less than ideal tastes that remain in the plants as a result of fertilization. I have been using compost tea throughout the growth of the plants. My tap water's ph is ~7.24 so I need to adjust it down to closer to 6.2 so that the roots remain happy. I use a diluted amount of citric acid to lower my natural ph to the 6.2-6.8 range recommended for flushing cannabis plants. Since I'm in the bay area and flushing is recommended for the last 2 weeks of growth and I have been growing outdoors for over 10 years, my plants seem to demand harvesting either the last week of September or the first week of October, so we're getting close.

The flushing process results in a better, cleaner, and more natural tasting flavors that can be spoiled in non flushed plants by residual nutrients. Here are the recommended ph levels for flushing your plants, courtesy of ChatGPT:

“Plain pH-balanced water” = just clean water, adjusted to the proper pH range for your medium.
  • Soil: 6.2–6.8
  • Coco: 5.8–6.2
  • Hydro: 5.5–6.0
Hope this helps new growers to attain a more flavorful harvest.

Happy Growing!

But it’s not scientifically proven
 
I disagree. Here's what my research, science and 20 years of growing tell me:

pH has a direct effect on nutrient uptake in cannabis. Even if you’re feeding the plant the perfect nutrients, the wrong pH will lock them out, leading to deficiencies and slowed growth. Here’s how it plays out:

🌱 Why pH Matters
  • Cannabis roots can only absorb each nutrient within certain pH ranges.
  • Outside the right range, nutrients precipitate (become unavailable) or get absorbed in excess, causing lockout or toxicity.
  • This is why you’ll sometimes see yellowing, purpling, or leaf burn even when nutrients are present — it’s a pH issue, not a deficiency in the formula.



⚖️ Ideal Ranges​


  • Soil grows: pH 6.0 – 7.0 (sweet spot ~6.3–6.5).
  • Coco / Hydroponics / Soilless media: pH 5.5 – 6.5 (sweet spot ~5.8–6.2).

Within these bands, cannabis can take up:


  • Nitrogen, Phosphorus, Potassium efficiently.
  • Micronutrients (Calcium, Magnesium, Iron, Manganese, Zinc, Copper, Boron) without lockout.



🚩 What Happens if pH is Wrong​


  • Too low (<5.5):
    • Calcium & Magnesium lockout → weak stems, blossom end rot–like issues, leaf necrosis.
    • Phosphorus becomes less available.
  • Too high (>7.0 in soil, >6.5 in hydro):
    • Iron, Manganese, Zinc deficiencies → yellowing new growth (chlorosis).
    • Phosphorus lockout → slow growth, purple stems, weak buds.



🔧 Managing pH​


  • Always test your input water (tap, RO, or rainwater).
  • Mix in nutrients first, then measure pH.
  • Use pH up (potassium hydroxide) or pH down (phosphoric acid, citric acid) to adjust.
  • In hydroponics, check both reservoir pH and runoff pH regularly — drift is normal, but you want it to stay inside range.
  • In soil, occasional runoff checks help spot salt buildup or pH swing.



✅ Bottom line:
pH isn’t just a number — it’s the key to unlocking nutrients. Keep it in range (6.0–7.0 in soil, 5.5–6.5 in hydro/coco) and your cannabis plants will grow faster, healthier, and produce better yields.
 
I usually give my plants water with epsom salts last week and a half or so. I let the plants use up every last bit of nutrients the leaves have left. The plants usually drink next to nothing I find when they’re at the end of their lives. I keep my water up around 6 1/2 that’s indoor and outdoor plants. They all seem to be happy. I grow in containers and in the ground. Salt grower with some worm castings here and there. I find to keep it simple is the way to go. I’m too lazy to be making teas and amending soil frequently. The plants don’t care where the nutrients came from.
 
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