Flushing and overwatering?

[Weedfreak]

So my girls were showing signs of nute burn. I flushed them with plain water. This morning, the were showing signs of over watering. What am I doing wrong?

 

[golfnrl]

Hey Weedfreak...can you give a little more info, maybe throw up a pic or 2? What's your grow medium? What stage of growth? When you say you flushed your plants with plain water what does that mean? When you see nutrient burn you could just back off the nutrients a little bit and not flush your plants at all. To flush a plant for salt build up run plain PH'd water at 2 x the grow pot's volume for soil and 3 x for coco. I.E. 5 gallon pot = 15 gallons of water. Check the EC/PPM of the last of the run off. It should be the same as the EC going in. If you are growing in soil let your pot dry out completely before watering again. If coco, after the flush has completely drained, immediately water in a very mild (1/4 to 1/2 strength) nutrient solution. Coco does not hold nutrients.

 

[Weedfreak]

Thank you golfnrl I'm growing in 6:3:1 coco/perlite/vermiculite. The girls are well into the flowering stage. I trimmed off all the damaged leaves yesterday, but will check later and put some pics up then if warranted. Thank you for taking the time.

 

[Weedfreak]

They are a little more than 4weeks into flowering.

 

[golfnrl]

Thx for the pix...it helps. It looks like there is almost some nitrogen toxicity but not sure because it looks like they are drooping from too much water. I'm leaning toward too much food and high PH or salt build up at the roots. If you haven't watered them yet, don't. Let the pot get light but not bone dry because as you know your coco should stay moist.

Then, I'd suggest watering your plants to runoff with plain PH'd water. If you know your starting EC and it's less than .4 add cal/mag to bring it up to .4. But don't add any nutrients, water til run off and measure. The EC should be very close if not matching what you started with. It will be OK to go one watering cycle with just plain water.

I've flushed my plants as I described earlier when they were 5 weeks into flower because they were dying.

At 4 weeks into flower your options are limited.

 

[golfnrl]

One other thing to look for is bugs. Have you checked your plants with a loupe? Maybe spider mites or other such critters on the under side of your leaves?

BTW...I tried to add this as an edit to my comments but the system would not save it that way. I hope this isn't a duplicate.

 

[Weedfreak]

What is EC? Is it easy to measure? Do I have to buy a special gadget?

 

[golfnrl]

Electrical Conductivity. It measures the total concentrated salts that are dissolved in your nutrient solution. In other words its a measurement of the strength of your nutrient solution. You need an EC meter to measure it. There are several brands, I use BlueLab. If the nutrients are too strong it will burn the plants and cause other issues like nutrient lockout.

I grow in coco and use the EC meter every time I mix nutrients. If you don't have an EC meter mix your nutrients at 1/4 to 1/2 strength and watch your plants to see how they react.

https://www.growweedeasy.com/measuring-nutrients-cannabis
https://www.growweedeasy.com/ppm

 

[golfnrl]

A TDS meter can be used to measure PPM. PPM is also a measurement of how mush stuff is in your water and nutrient solution.