PH Level and Crop?

[Harold Sukhbir]

Hi All,

In another discussion, some of us are trying to determine the ranges of PH for best growth of different crop grown. This can become a general guide for maintaining specific PH levels to suit the crop you choose to grow.

So, what is your average system PH and what plant (plant doing the best) do you notice thriving at this PH level?

[Harold Sukhbir]

Hi All,

We've come along this thread on PH level and crop and it dawned on me we didn't even post a chart of some kind as a guideline.I am aware this applies mostly for soil growing but we have to start somewhere i guess.

 

Plant Preferences for pH

Very acid (pH 5.0 to 5.8)	Moderately acid  (pH of 5.5 to 6.8)	Slightly acid  (pH 6.0 to 6.8)	Very alkaline  (pH 7.0 to 8.0)
azalea blueberry celeriac  chickory crabapple cranberry eggplant  endive heathers huckleberry hydrangea Irish potato lily  lupine  oak raspberry  rhododendron rhubarb shallot sorrel spinach beet spruce  wild strawberry sweet potato watermelon white birch	bean begonia Brussels sprouts calla camellia carrot collard greens corn fuchsia garlic lima bean parsley pea peppers pumpkin radish rutabaga soybean squash sunflower tomato turnip viola	asparagus beet bok choy broccoli gooseberry  grape kale kohlrabi  lettuce mustard  muskmelon oats okra onion pansy  peach  peanut pear peony rhubarb  rice  spinach  Swiss chard	acacia bottlebrush cabbage  cauliflower  celery Chinese cabbage cucumber  date palms dusty miller eucalyptus geranium oleander olive periwinkle pinks pomegranate salt cedar tamarisk thyme

 

[David Waite]

Amen to that Nate. I can spit more water than rain drops here.

Nate Storey said:

You guys are totally right.  If you have access to rainwater- that's a fine way to go.  Here in the high desert though. . . that's not really possible.  You gotta use what you got!

 

Good luck with the watermelons Paul.  I've been making myself sick on them lately. . . they can be pretty finnicky.

[Kobus Jooste]

Got in a little late on the pH thing in terms of rain water.  I have been on it for almost 2 years because of a drought that makes using municipal water almost impossible.  While I have had serious issues controlling my small system, with pH going below 6.5 at times, my large system running on duckweed has been plugging away at a steady 7.2 to 7.4 for years with no buffering added.  The research unit is all fiberglass and the small system a mix of food grade plastics.  Only other difference is the crops, the media (quartz pebbles) and the fact that the samll system's water came off a steel roof and the other system is fed of polycarb and cement tile. 

 

In all, the rain water has worked out fine for me apart from the constant need for keeping an eye on the small system.  I just think there were so many variables going at the same time for the two systems that it will take some time for each individual grower to figure out how their system will perform on rain or RO.

[Harold Sukhbir]

Hi Kobus,

Good to hear from you! I know that both of us were/are using rain water in our AP. The constant buffering of rain water with calcium carbonates started to create chemical lockout for me until this topic, where Nate was kind enough to explain the alternate buffering sequence in order to balance the chemistry. I know your AP is at low ebb waiting for weather and by then you'll place the second pump in the system, so waiting to here more from you.

On this topic of suitable PH and crop I think that not many AP'ers target a specific PH level but rather adopt the full range between buffering, so its easy to tell the crop which do well within a range, but no specifics as to optimum PH for Crop growth.

[David Waite]

Harold this has been an informative discussion on how to handle ph. I really think with the exception of Nate we are all living with what our systems have and growing accordingly. Nate is able thru a RO to manipulate his ph to the ideal range of 6 and grow like mad. In my discussion on root crops not many people reply because I just dont think   many are doing it yet not because of they dont want to comment. I am please that many crops will grow outside their optimal range and still produce. I will change my media this winter and be able to drop my ph accordingly and then I think my system will be perfect. I am very pleased so far as to growth and flavor but the production side is light on fruiting crops with the high ph range. Nate has taught me a bunch of tricks as well. Great discussion.

Harold Sukhbir said:

Hi Kobus,

Good to hear from you! I know that both of us were/are using rain water in our AP. The constant buffering of rain water with calcium carbonates started to create chemical lockout for me until this topic, where Nate was kind enough to explain the alternate buffering sequence in order to balance the chemistry. I know your AP is at low ebb waiting for weather and by then you'll place the second pump in the system, so waiting to here more from you.

On this topic of suitable PH and crop I think that not many AP'ers target a specific PH level but rather adopt the full range between buffering, so its easy to tell the crop which do well within a range, but no specifics as to optimum PH for Crop growth.

[Harold Sukhbir]

Hi David,

David: Nate is able thru a RO to manipulate his ph to the ideal range of 6 and grow like mad.

 While low PH is ideal for nutrient to root absorption, we can't discount the fact that there is also the option of foliar spraying our nutrients. This especially applies to the folks with higher pH source water. If can't avoid running a system with lower than PH of 7 ppm - 7.4 ppm you could adopt foliar spray for nutrient deficiency. The plants will absorb them through their leaves even though the system has reduced availability of nutrient in the water because of PH range. Also low PH may not be ideal for some who grow crop liking higher PH's. So it will depend on what you want to grow as well. Then there is the effort and expense that is required with regular buffering. Rainwater and RO will definitely appeal to people with large(even commercial) systems where producing a high quality crop on a timely basis is important.

Yes, I agree, very informative and I'm learning a lot!

[TCLynx]

It's interesting that some crops in the hydroponic pH charts show they prefer very acidic conditions (I'm thinking of cucumber at the moment) and then on the soil pH chart it shows cucumber being in the alkali side.  I wonder if perhaps it varies by variety.  I have to admit that I've not had much luck with cucumbers or related plants in my big AP system which is the one full of shells and running the 7.4-7.8 pH which will mess with the Iron needed to keep cucs happy and the calcium is probably messing with the potassium that family needs in good supply.

 

I am glad to report that in the 300 gallon system which does not have shells, I have a lufa growing like mad which is in the same family with cucumbers so perhaps I'll manage cucumbers in AP someday!!!!

[TCLynx]

Watercress can be a huge cash crop and it loves alkali water.

[David Waite]

TC I am growing some in my system and have eaten it fresh along the streams. I have never been able to develop a taste for it. It is a cross betweeen horseradish and bolting lettuce to me. Very peppery aftertaste. How do you eat the stuff.

TCLynx said:

Watercress can be a huge cash crop and it loves alkali water.

[TCLynx]

I've also not really developed a taste for it fresh myself either.  It is good mixed into an omlet or scramble though.  People who like arugula probably love it though.

My ducks seem to like it.

[Robert Chlebowski]

I've read in Gardening Indoors with Soil & Hydroponics by George F.Van Patten and Hydroponic Crop Production by Joe Romer that when plants take in nutrients they change the concentration of nutrients in the feed water and that this swings the pH, usually towards alkalinity. I am puzzled because I thought that pH is a measure of hydrogen and that its a means of the dissolved salts to 'float around' in a hydrogen cloud so to speak. The more dense the cloud (lower pH) the better the dissolved salts float around and the more likely the roots of the plants will find these nutrients. I don't know why pH will fluctuate higher (loss of hydrogen?) when nutrients are being taken up.

My best guess is that the hydrogen is used to dissolve the salts into the feed water in the first place, so, as the demand for nutrients increase (as plants become mature for example) the demand for hydrogen to dissolve those nutrients also increase. (This is apart from the obvious acid neutralizing substances in the fish tank, example potash)

Any comments?

[Alex Veidel]

Ooh, ooh, I feel like the answer to this is in my head somewhere....did it have something to do with cation exchange? I'll go refresh my memory when I have time and get back to you.

Robert Chlebowski said:

I've read in Gardening Indoors with Soil & Hydroponics by George F.Van Patten and Hydroponic Crop Production by Joe Romer that when plants take in nutrients they change the concentration of nutrients in the feed water and that this swings the pH, usually towards alkalinity. I am puzzled because I thought that pH is a measure of hydrogen and that its a means of the dissolved salts to 'float around' in a hydrogen cloud so to speak. The more dense the cloud (lower pH) the better the dissolved salts float around and the more likely the roots of the plants will find these nutrients. I don't know why pH will fluctuate higher (loss of hydrogen?) when nutrients are being taken up.

My best guess is that the hydrogen is used to dissolve the salts into the feed water in the first place, so, as the demand for nutrients increase (as plants become mature for example) the demand for hydrogen to dissolve those nutrients also increase. (This is apart from the obvious acid neutralizing substances in the fish tank, example potash)

Any comments?