PH Level too low; raise immediately or gradually?

Hello again,

I have two autos in early flowering and just tested my PH for the first time. Yes…I’m new. The reading from the plants in Miracle Gro is way too low. It’s sitting around 4.5 according to the color charts. The plant looks well but I’m concerned I’ll end up with airy buds or hermis.

I have General Hydroponics PH kit. My question is how best to raise the PH? Should I flush until the run off is raised or attempt to raise it gradually over time? I’m in 3 gallon pots and ran 2 gallons of tap water PH7 through. I then ran a gallon with the PH raised to 8 and the run off was still too low. Sorry I don’t have a pen.

Any suggestions would be greatly appreciated!

@SteveG being concerned about your pH is the first step to insuring you have the correct pH.

That said, I would not trust the “color chart method”, you really need an accurate pH meter.

There are a number of good options out there from the Bluelab to the Extech and another that is very popular but I don’t remember the name.
I would be hesitant to make big changes until I was sure what the pH is.

4.5 is really low and I would be wanting to get it into range as quickly as possible but you want to be sure that 4.5 is an accurate number before making that drastic change.
It can be stressful for the plants if things change too fast so care must be taken when making big changes.

I am on my first grow and will tag in a few experienced growers for their opinions.
@Donaldj @Countryboyjvd1971 @timmyv324 @highcountrygal @Niala
@garrigan62 @Covertgrower @dbrn32


I would work on getting it up immediately


All out of likes, @merlin44 as merlin44 stated, ph is important.
How are measuring the ph? @SteveG the other important factor when changing ph is to change it gradually as not to shock the plant. Dolomite lime is your friend in this case to assist in keeping the ph higher.
What specific miracle grow soil is it? A lot have slow release fertilizers that can cause havoc later, especially flowering. So if you did a flush, it released a lot of nutrients, which may cause more issues.
A picture under normal light farther assists in trouble shooting. I hope this help. Happy growing.


Thanks. It’s in Miracle Gro Moisture Control w/ 6 months feed. Total rookie mistake. I took one of the 3 I have going out of the Miracle Gro about 2 weeks ago. It was beginning to claw. The other two were looking good. They still do which makes me wonder about the inaccuracy of the PH measurement. I would think there would be some yellowing if the PH was actually 4.5?

I ordered a meter which arrives on Sunday. I’m going to let it dry out then take a look again on Monday. I hope I didn’t cause too many issues with the flush. Time will tell.


I agree 100% with @Covertgrower. If you get some of the fine dolomite lime and top dress a few tablespoons worth, then run a decent flush she will come back fairly quickly for you.


It’s been a little bit since I’ve grown in soil but I used to do as many flushes as I wanted and never once worried about it. What I tried to do as keep the flush under 10 minutes so as to not continually drown the roots in water.

Usually when people water they water to the point where there is a small amount of run off anyways, which is indicative of the soil being saturated, therefore it has to allow some of the water to “run off” because the amount of water present exceeds the amount that the soil is capable of holding. With this in mind a flush can be almost the same as a normal watering as long as your not flushing for an extended period of time. You can even cut it down to 5 minutes if you’d like. I can easily get 15 gallons of water through a 5 gallon bucket in 5 minutes. Just some food for thought. I personally don’t think you did anything wrong with your extra flushing


I agree with the @dbrn32 @TDubWilly @Covertgrower @merlin44 gotta get it up but don’t aanna shock it to bad. I’m pretty sure hydrated lime is faster acting than dolomite which is kinda s constant releasing lime where the hydrated is a fast acting lime. But both do the same thing. Just watch the amount you put in cuz it will fry it to especially that small. Good luck my friend all you can do is do it !!!


I personally don’t think bringing the pH up all at once will shock it. In DWC from time to time the pH will get out of whack. I’ve made pH changes of 3+ points in one fell swoop and never encountered any problems. I wouldn’t see why it would be any different in soil.


I appreciate the input from everyone. Very helpful!! I did confirm the PH @ 4.4 today. I bought a meter and the results were consistent with the cheap color tester. I flushed it with PH Up and brought it to 5.8. I didn’t want to risk over doing it. I’ll test again the next watering. I’m surprised the plant looks as good as it does. I have no yellowing which it may be more tolerant but I think my yield will be impacted as a result I’m sure.

Anyway, thanks again. This is a great resource!

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