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What's the most accurate way to measure soil pH

organic_wonderful
13 years ago

I have a pH meter and have been told there is a way to use these pH pens to measure soil pH accurately. Is this true? If so, what's the procedure?

I've been lead to believe that those analogue pH meters (the ones with a long pH probe you stick in the soil) are completely inaccurate and are basically useless. I'm not sure if this is right, but I'd love to find out.

I understand you can get chemical tests that use colour changes to give a pH indication, this might be the solution.

What do you guys think?

Comments (51)

  • Kimmsr
    13 years ago

    I have used the inexpensive ($40 to $100) pH meters and have found most of the time they give inaacurate readings reporting soil pH the same as Vinegar and a solution of baking soda, and they will not tell you if your soil has sufficient levels of Calcium and Magnesium. A good reliable soil test from a soil testing lab is much better.

  • ericwi
    13 years ago

    If your pH meter has a calibration feature, and you have a solution of known pH, then you can calibrate the meter, and it should be accurate to +/- 0.1 pH unit. Here in Madison, Wisconsin, our tap water, supplied by the city, has a known pH = 7.6, so I am able to use it for calibrating my pH meter. I use 5% white vinegar, from the grocery store, for the lower point. I have used both a pH meter, and dye indicator solutions, for testing soil pH. The results agree, however, dye indicators are only accurate to +/- 0.2 pH unit. Does your "pH pen" have a battery, and an LCD display?

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  • Shane_Genziuk
    13 years ago

    No doubt that the lab is going to give you the best results. I'm using one of the chemical test products that seems to be fairly accurate for what I need it for. Cost me about 20 bucks and used it a dozen times so far.

    Here is a link that might be useful: pH test of used coffee grounds

  • ericwi
    13 years ago

    There has to be water present in order to measure pH. The source of the water can affect the test results, and it may dominate the test results. Here in Madison, our tap water has pH = 7.6, so it can't be used for making calibration standards, nor can it be used for hydrating a soil sample. I have used steam distilled water in the past, however the steam distilled water has some lime content, and careful measurement indicated that the pH was around 7.2, so now I am using RO(reverse osmosis) de-ionized water, pH = 7.

  • albert_135   39.17°N 119.76°W 4695ft.
    13 years ago

    At the university lab, many decades ago, we would add some water to the soil and shake it up daily for a couple of weeks, ideally a month, testing with the pH meter. This way we could calculate buffer capacity. See bcn.boulder.co.us: buffer capacity. Personally I think that if you don't know about buffer capacity, and don't want to find a lab that will determine buffer capacity for you, then you might as well just shake the soil with some water and use an aquarium test strip.

  • TXEB
    10 years ago

    That's actually a rather poor way to measure soil pH, but I've seen a lot of people do it.

    For a good soil pH test you first need a representqtive sample of the soil over the area of interest. A hole doesn't provide that. Second, the method is based upn extraction, typically one-part soil to one part water. But if the soil is heavy in clay or organic matter, a 1:2 ratio can be used. Next take an amount of your mixed representative sample - depending on how you're going to measure as little as 2 tablespoons or as much as 1/4 cup will do - and in a very clean container mix it well with the appropriate amount of distilled water (the grocery store or drug store bottled variety will work just fine). A clean glass jar with a tight fitting lid works great for mixing - shake for about 30 seconds, the let it settle for 30 min's to one hour. Then use a suitable method to determine the pH of the soil extraction liquid after settling. Suitable methods can be a good glass electrode or a good colorimetric indicator. The stick-in-the-soil pH probes just don't work.

    For more on testing soil pH and other measures of soil health you can do, see the link below.

    Here is a link that might be useful: USDA Soil Quality Test Guide

  • Kimmsr
    10 years ago

    What is the source of the water you suggest using Trees?
    Unless that water is pH neutral it will affect the reading you get whether using a pH meter or pH strips. Then that test will not give you the information you need to make an intelligent decision about what to do to maybe correct any anomaly.

  • garyz8bpnw
    7 years ago
    last modified: 7 years ago

    Agree that distilled water is best to use. It is inexpensive at the grocery or drig store. Do not use their "reverse osmosis" (RO) water. Some salts can be in there effectiving buffer capacity. Do not use tap water even if pH 7 because of same reason.

    Among pH paper options pHhydrion pH test strips typically work best and well enough. That is if an appropriate epresentative soil sample is taken and prepared correctly. Also the test strips must be stored correctly so they are not sun bleached or contaminated. I forget if they have an expiration date to help avoid risk from being effected by acids or bases in the air over time? For instance trace levels of vinegsr (acetic acid) or ammonia.

    If more accurate or reliable methods are desired, it's hard to beat a pH meter.

    Even pH pen type meters can be used IF calibrated. Labs assure success by using standard pH buffers that they have purchase at agriculture or science supply houses. They can be liquids or capsule powder that you use in distilled water to make the calibration buffer needed. The buffers are not expensive and the liquid ones store well in a refrigerator.

    Use full stength undiluted calibration buffers (it takes only a little each time). One can buy little throw away cups to hold the test buffer sample. Or just use a clean soda bottle cap as the calibration cup. Throw away the little sample after you use it each time. Do not pour it back to the supply bottle and risk contaminating it.

    Basically to measure your soil water samples correctly, you need to calibrate your meter right. If you have an expensive meter with only a zero adjustment and or a pH 7 single set point, it may not be very accurate in meauring any pH but 7.0. Get a dual calibration set point meter. Even inexpensive units can be surprizingly accurate when stored as recommended in the user manual and calibrated correctly.

    To calibrate a dual set point meter you need two calibration buffers. Select them to bracket your expected sample value. Meter calibration simply sets an accurate measurement performance range between two set points. The process of cslibration also makes sure that your meter is working correctly and does not need cleaning or service.

    If routinely soil samples below pH 7, use pH 7.0 then pH 4.0 buffer to calibrate. First calibrate the "neutral" set point which is also the "zero range set point". Do this by putting the probe into pH 7 buffer and then setting the meter adjustment to pH 7.0. Thus, you have set the meter "neutral point" to 7.

    Then rinse the probe and put it into the pH 4 buffer and set the "range adjustment" to pH 4.0. Rinse it again and retest the pH 7 buffer to ensure it still indicates 7.0. You might then need to "fine tune" both set points by doing the two setting steps again as above. This is because the dial set adjustments can affect each other a bit.

    Important: if you can not set the meter range right, then the battery or meter can not be trusted.

    To measure soil samples above pH 7.0. Calibrate with pH 7 and pH 9 buffers, as above. In this case, obviously set the range calibration value to pH 9.0, because you're using pH 9 buffer.

    Once you trust your meter you can do test a significant number of samples in that session. It never hurts to test the meter in the middle of the sample set and or end to make sure the calibration accuracy did not slip.

    A calibrated meter is hard to beat and will likely always be the most accurate measurement method. However, one can also use a calibrated meter to analyze the accuracy of using pH paper or indicator dye (colorimetric) tests.

    People also often like to spot test sample batches to see what meter calibration buffers they need to use. Or check to see if samples need to be taken and meter tested in the first place. pH paper is sometimes cost effective and helpful in this way. But I would not trust it alone.

  • garyz8bpnw
    7 years ago

    Thx I just see so many pH measurement blog comments talking about only trusting pH meters or that pH papers work fine. Just wanted to describe the limits better. I revised the discussion above to add pHhydrion strips to the discussion.

  • harry757
    7 years ago

    garypnw, I live just a few hours north of you in Canada........any idea where one can buy the test strips you mentioned? Are they a test strip used primarily for soil testing? For example, is the testable pH range appropriate for soils - i.e a pH range most likely between 5.5 to 8?

    Harry

  • jolj
    7 years ago

    How important is distilled water to you?

    You can distill water at home for $400.00 to $2000.00, not cheap but distiller will last many years. I think pH is less of a problem for most gardener, most plants do well in 6.0-7.0 pH. Blueberry plant need a lower pH, but most plants do well in 6.0-7.0 pH. So I test once every 2-3 years, or when I have a problem, that I can not find an answer for. That has happen once in 40 years, the first 20 year I never did a test on my very acidly 5.0-5.5 soil. I never had much of a problem & no BER on my tomatoes. Being an organic gardener with compost that is at 6.5-7.0 may help.

    Without testing I am not sure.

  • garyz8bpnw
    7 years ago

    Looks like Amazon has them listed in pH 4.5 to 8.5 range and nearby ranges too.

    Amazon.com: ph hydrion test paper https://www.amazon.com/gp/aw/s/ref=is_s?k=ph+hydrion+test+paper+4.5+8.5

  • dchall_san_antonio
    7 years ago

    Who cares what the pH is? If you don't know why the pH is where it is, you can't do anything meaningful about it. You need a soil test that gives you salt balances.

  • garyz8bpnw
    7 years ago

    Last time I purchased distilled water was at Safeway for $2.49 per gallon, which is tons for this use.

    I grow tropical plants inside and have found that misting them with rain or distiiled water does wonders for them, giving a vibrant look. When I collect rainwater it has tree pollen pollution in it and I can't store it without molding. Using a gallon per day I calculated that I can rather quickly save money making my own distilled water.

    Good news! You can distill at home with a very reliable system costing much lesd that $400.

    I paid just under $100 for 1 gallon per run unit. Mine is a white colored unit that uses a clear plastic collection jug. I can load my unit with less tap water than a gallon, to make smaller batches too, even with as little as about a cup generated.

    Various home units are carried by Amazon, listed at the link below with multiple sources of my particular unit listed under different vendor trade names.

    Amazon.com: Home Water Distiller https://www.amazon.com/gp/aw/s/ref=is_s?k=Home+Water+Distiller

    I've used my distiller DAILY for over a decade now! That is 365 x 10 x $2.49 = greater than $9,000 worth of water made. There is cost for the electricity used and some heat generated in the process. However, we live in a cool climate and set our house night temperature on our furnace to 58 F, so the heat is usually appreciated. I run our 900 watt still at night on a $10 24-hr light timer, rated at 1,250 watt.

    Each run takes about 3 hr and one only hears a small fan running. The unit has automatic turn off and overheating protection, both carried out by the same reliable internal bimetal sensor detector system.

  • jolj
    7 years ago

    Sure you can.

    Blue berry plants will stop baring fruit & die if you play with the pH to much.


  • daninthedirt (USDA 9a, HZ9, CentTX, Sunset z30, Cfa)
    7 years ago
    last modified: 7 years ago

    "any idea where one can buy the test strips you mentioned?"

    Just Google "pH strips". They're all over the place.

    "Who cares what the pH is?"

    I care. If your pH is highly alkaline or acidic, many plants will suffer. You don't need a fancy pH meter to measure that. And yes, there is plenty that you can do about it. Many additives that will bias the pH up or down. Now, that being said, you need to test the pH of your irrigation water as well. My soil is alkaline (no blueberries here, unfortunately), but my ground/tap water is alkaline as well. So trying to acidify my soil is a losing battle. I guess if I collected rainwater I might have a chance. Acidifying the tap water I use to irrigate with is an expensive proposition.

    As to salt balance, I would say "who cares"? If you don't live close to salt water, or road crews don't salt the roads from which water runs off into your bed, salinity is unlikely to be an issue.

  • kokopellifivea
    7 years ago

    PH is overrated.

    I grow tomatoes easily in pH 7.5. I believe those who report good results in the 5s. That's typical for most garden vegetables.

    It's very worthwhile to know where you are at. I know better than to mindlessly add lime to my soil. I default towards more acidic ferts. I add sulfur. I'm not too worried about dramatically changing my soil chemistry over time.

  • jolj
    7 years ago

    kokopellifivea, that is good for you with 7.0 soil, your default works for you.

    I have 5.0 to 5.5, so my default on everything but blueberry plants is gypsum or hydrated calcium sulfate, if that dose not work I go to lime.

    I agree that mindlessly adding anything to your soil is bad.

    Good compost should not hurt, but one should think about what they are doing to their garden.

    After all, it is living art, that you put in you mouth.

  • kokopellifivea
    7 years ago

    Right, but that's the whole idea---to lean against the wind.

  • daninthedirt (USDA 9a, HZ9, CentTX, Sunset z30, Cfa)
    7 years ago

    That's a fair point that pH can be overrated. Because most people don't really have a problem with pH. But some people do. And for them, it's pretty horrible, but there are soil amendments that can fix it. For example, highly alkaline or acidic soil can completely tie up micronutrients, making them unavailable to plants. I know alkaline soil makes gardening life real hard in at least large parts of Arizona.

    That's why a pH meter for gardening is kind of overkill. I don't need to know the pH to two decimal places. I'd like to know if it is seriously alkaline or acidic, and pH paper will tell you that in spades.

  • kimmq
    7 years ago

    Most all nutrients plants need to grow strong and healthy are most available in a pH range of 6.0 to 7.0, so a soil pH is of interest only to those that wish to grow strong and healthy plants.

    Plants also cannot use Calcium well if the Magnesium levels are out of whack and vice versa. A $50.00 pH meter, or those litmus papers, will not tell you much of anything about the levels of Ca or Mg.

    kimmq is kimmsr

  • waynedanielson
    7 years ago

    simple questions are certain to generate answers that are surprisingly complex.

    in this case, there was a land mine waiting, just by asking about pH testers.

    For most gardeners, it's enough to know if you're high or low. and while reliability can be a concern, there are enough simple and cheap testers out there to choose from. With any testing or monitoring tool, proper calibration is important to long term reliability, as is knowing how to use it. I do it all the time...I'll buy a new toy...er, useful tool for increasing productivity...and the first little bit is all about learning about what it is, what it can do, what it can't do, and how to use it effectively.

    So take that time upfront, whatever it is you are doing. Taking a soil sample to send to the lab? Calibrating testing equipment? take some time up front. With simple litmus test strips, you can get a fair idea of acid or base...but if you are useing alkaline water to test an acidic soil, you're results are going to be confuddling. Every tool has it's limitations...(comment about what she said deleted).

  • daninthedirt (USDA 9a, HZ9, CentTX, Sunset z30, Cfa)
    7 years ago
    last modified: 7 years ago

    No, litmus test strips will only tell what side of neutral the medium is on. They won't tell you how badly acidic or alkaline it is, which is what you really want to know. Real pH strips will tell you how badly.

    The tap water you use to test with is likely what you irrigate with and comes from the groundwater that is resting in the kind of rock chemistry you have in your bed. Highly unlikely you'll be using alkaline water to test acidic soil.

    But yes, pH meters are fun toys that, properly calibrated, will tell you lots more than you need to know. The OP is asking "what's the most accurate way to measure soil pH?" My question is why the most accurate way to measure it is of any importance.

  • monomer
    7 years ago
    last modified: 7 years ago

    I thought garypnw gave a really good and thorough response explaining how to use a pH meter properly.... thank you.

    However if that kind of accuracy is not really needed then I might suggest those cheap "drop" pH tests as a viable alternative... the kind that come with a test tube (vial) and a chart and a bottle with the eye dropper tip... its what we used to test pH in koi ponds and aquariums. I've used it with distilled water and after letting the soil particles settle for a time (an hour after shaking the bottle), the water solution at the top half of the bottle, though with some residual haziness left and not quite colorless, is still easily clear enough to accurately establish color (put 5ml of it into vial with 5 drops and shaken) based against the color chart. Unlike paper tests, I find these drop tests easier to determine shades of color to the point I'd say +/- .2pH is entirely possible... and do you really need greater accuracy in the garden? REALLY? ...like how necessary it is to know your soil pH anyway? I guess it'll depend upon whether you're having issues with your growing plants doesn't it? I believe pH is quite variable by depth and location... thus we see the suggestions to take samples at many locations and at a depth through the top 6-8" (considered the root zone) and mix everything together prior to testing... so all you're really getting is just an averaged pH... this does nothing to establish the variance in pH throughout the soil. I read somewhere that roots to some extent alter the pH at their interface with the soil solution and thus plants are able to obtain what they need for mineral nutrients within a reasonable variation of soil pH. If that's indeed so, then it would explain why most plants seems to have no issue growing well through a wide range of soil pH's (say ~5.5-7.5)... With this being so, then the real point of interest would be mineral balances and overall nutrient levels in the soil, wouldn't you think? If one buys into this sort of reasoning then a complete soil lab test would be the way to go I'd think.

  • daninthedirt (USDA 9a, HZ9, CentTX, Sunset z30, Cfa)
    7 years ago

    I have to wonder if these pH test strips are really just paper saturated with what you use in the "drop" tests. But indeed, those drop tests too are a sensible way to get a quick fix on your pH situation.

    Yes, I believe soil pH tends to increase with depth. That's because surface leaching with rainfall (which is usually slightly acidic, from carbonic acid) tends to cleanse out the calcareous content in the near-surface. In fact, that's true for many soil constituents, which is why if you're getting your soil tested, don't just scrape a sample off the surface. That won't be representative of your bed. I believe that this stratification of soil beds is especially noticeable in no-till beds.

  • monomer
    7 years ago
    last modified: 7 years ago

    I'm not sure if the drops and the papers contain the same "stuff" but I do know that the number of drops per 5mL (vial) seems to be an important measurement mixture ratio... it appears to me that the hue is what determines the reading of pH level but the difference is often so slight that shading (intensity) is also a major factor in making the distinction easier to read... thus possibly resulting in a higher accuracy for many people who get intimidated by color charts anyway. Just a thought.

    Yes, rain in the east and mid-west tends to be acid (though not like in the "good" old days of maximum coal burning) but its my understanding that water can flow both ways in the soil depending upon local weather. When its raining water moves down and carries with it certain minerals but during doughty periods water moves up through the soil and also carries some minerals with it... however since most of us water our plants regularly during droughts I suppose the minerals can be expected to pretty much go into the sub soil and stay there, though watering with ground water will likely replenish many of those minerals.

    Since so many of us like adding organic matter to the top layer of soil... decomposing matter tends to acidify soils (such as in nitrification) which is yet another source promoting pH layering in the root zone. So, yes I believe pH will often be dependent upon the depth of soil. In fact a good many things can cause pH to change within a growing season... the type of fertilizer used, the plants themselves as they remove certain minerals from the soil, the ratio of rain to ground water applied, etc. This is why I really don't think precise pH measurement is anything to stress-out over UNLESS your soil is at the extremes (outside say 5.5-7.5) and then its really important to know.

  • garyz8bpnw
    7 years ago
    last modified: 7 years ago

    Yes. Exactly right on the statement about dye concentrating being critical and it setting the color density.

    A pH meter is great if you need to do alot of readings quicky with great accuracy. I used to work in labs. For a home hobbyist doing a small number of readings, I probally use the dissolved dye methods. Yes indicator dip strips use the same or similar dyes. You dip and pull out so the dye is not extracted. The take in account the buffering capacity of the dye versus volume of liquid sticking to the paper. Some dye types stick better to paper than others and don't leach off so easily.

  • daninthedirt (USDA 9a, HZ9, CentTX, Sunset z30, Cfa)
    7 years ago

    True that rain used to be more acidic in the olden more polluted days, but as rain falls through the atmosphere it absorbs CO2, and forms carbonic acid (which is a very weak acid). The strength of that acid is determined by the concentration of CO2 in the atmosphere. At least with current CO2 concentrations (increasing regularly), I recall, distilled water that gets in equilibrium with the atmosphere turns into pH=5.6 carbonic acid. That's rainwater with no pollution. I misstated it a bit above. Rain is not usually acidic. It is always (slightly) acidic. Always. That's one reason why high-rainfall areas tend to have more acidic soil.

    Now, my tap water is alkaline, so that will tend to make my soil surface more alkaline, but alkaline water won't leach calcereous content. It'll just leave it alone. The rain does leach it. So the net result is lower alkalinity in the upper layers, as long as it rains.

    Yes organic decomposition can produce acids, but it's also a heavily buffered mix. So it doesn't acidify much.

    But that's exactly right that soil pH is a non-issue for gardening unless it's off the charts.

  • toxcrusadr
    7 years ago

    It is important to know what you're starting with, i.e. where your native soil wants to be, because it's pretty tough to change it very much from that in most cases. I've been gardening 25 yrs in the same spot and I don't pay much attention to my pH anymore. It's neutral, it wants to stay that way, and I don't add pH adjusters, so it pretty much stays neutral. I can see if you had a very high or low pH and you were constantly having to push it towards neutral, and it constantly wants to go back, you might want to check pH every year or even less.

    BTW that carbonic acid rainwater, while it has a low pH, has very very little buffering capacity (or perhaps total acidity is a better term). Mix rainwater with an equal amount of hard tap water from limestone aquifers and the tap water will eat it for lunch.

  • daninthedirt (USDA 9a, HZ9, CentTX, Sunset z30, Cfa)
    7 years ago

    Yes, that's why rainwater doesn't do a job on acidifying calcareous soils. Doesn't have a chance against the dissolved salts in such groundwaters.

  • waynedanielson
    7 years ago

    There's two ways of approaching this question.


    If you want accuracy, go with a lab, or spend the $$$ and get serious testing equipment.


    If accuracy is that important, odds are, you already use a lab or have those serious testing tools. if you're looking to move away from a lab, or to have more immediate answers, and want to know what to get, that's a different question.


    When asked, this question is almost always about price and ease/accessibility.


    There has to be a middle ground. a way of encouraging people without insisting the default is always a lab test.

  • daninthedirt (USDA 9a, HZ9, CentTX, Sunset z30, Cfa)
    7 years ago
    last modified: 7 years ago

    It's pretty easy. For most home gardening, pH accuracy is not a question. That being the case, ease and accessibility of using strips or drops that will get you +/-0.5 of a pH is a given. What I would like to know, from people who are insistent about measuring pH "accurately", presumably with an electronic tester or lab test is ... why? There may be good reasons. For example maybe, if you are monitoring progress of some delicate pH-changing efforts. But for general gardening, high accuracy pH measurement is simply unnecessary.

    So it's not a matter of a middle ground. It's a matter of deciding the accuracy you really need, and figuring out the most economical way to get it.

  • albert_135   39.17°N 119.76°W 4695ft.
    7 years ago
    last modified: 7 years ago

    ''dchall_san_antonio(8 San Antonio) Who cares what the pH is? If you don't know why the pH is where it is, you can't do anything meaningful about it. You need a soil test that gives you salt balances.''

    Several decades ago I had an entire semester on pH. I think that dchall is onto something. Without a knowledge of what we called ''buffer capacity'' I cannot see any value to the pH of water whatsoever.

    Google ~ garden soil ''buffer capacity'' ~ and find page after page like:

    Soil pH and buffer pH: What's the difference?

    www.isafarmnet.com/ResearchPublications/06Nconf/E1.pdf

    Reserve acidity is the concentration of hydrogen ions attached to the negatively charged clay particles and organic matter. This is measured as buffer pH. Buffer pH relates to buffer capacity of the soil: ability to resist changes in pH. There is an equilibrium between active and reserve acidity in the soil.

    And:

    Soil Testing: - Clemson University

    www.clemson.edu/sera6/Lime%20buffer%20capacity%209-23-04.htm

    A New Method for Measuring Lime Buffer Capacity ... For soilsamended with heavy applications of organic materials (gardens, potting soils, flower beds, etc.) ...



    It is also called Cation Exchange Capacity (CEC). Purdue has a good description.

  • daninthedirt (USDA 9a, HZ9, CentTX, Sunset z30, Cfa)
    7 years ago

    Well, many plants know what the pH is, which is why people want to care about it. But that's exactly right that unless you know more about the soil chemistry, changing that pH is going to be hit-and-miss. Though at least you can hit-and-miss in the right direction ...

  • garyz8bpnw
    7 years ago
    last modified: 7 years ago

    I agree ... nobody cares about pH much ... unless their's is off and flowers or food crops do poorly. Then it gets important. Huge investment loss potential. I'll post some info about a current hydrangea color challenge that I have.

  • toxcrusadr
    7 years ago

    Absolutely. If you test it and it's in the range it needs to be for what you're growing, there's really no reason to go down the rabbit hole. If you have to change it, then it gets more complicated.

  • garyz8bpnw
    7 years ago

    Many people just much think that pH is in the water and fertilzer is dissolved for your plant in the water. But the truth is far different for many nutrients. For instance, charged nutrient ions stick to the soil minerals and charged surfaces. And the plant has to pull these away to get them.

    Plant roots produce quite dilute acids to knock off the nutrients and help solublize them. So how strongly the pH of the water helps nutrients stick and thus is important. Plants that require acidic soils may for instance nutrient starve in alkaline soils, even with plants nutrients such as potassium and ammonium being otherwise adequate.

    In this conversation some growers may just be growing vegetables, many of which are grow easily and are not fussy. I grow a huge range of hardy, semi-hardy tropical, and also some tropical (plants under lights). I can assure you some plants are quite fussy about pH, nutrient balance and loading.

    Most of my indoor tropicals are aerial epiphytic plants from Rainforests. They evolved with and are adapted to using rainwater which at times picks up nitrates from lightning storms and some bird or bat quano gifts at times.

    I've gone to misting some of my tropicals with distilled water to water some and others to just flush tapwater salts off of them. When grown in the house, I can't just hose them off. I see a huge difference with some of them when treated with distilled water instead of tap ground water. All of the plants treated this way look much more vibrant in general. I can also grow them much drier and they still look well watered.

    For awhile I collected rainwater but there is often so much tree pollen in it that it was cloudy and didn't store well either. So I've instead have used a little home still nightly for the last decade that makes a gallon of distilled per night.

    With distilled water surface mist on a leaf, the low buffering capacity lets the plants adjust their own surface pH. And salts don't build up on leaf surfaces and in crowns or leaf axils. Bromeliads do not do well overtime with ground water in their crown leaf water well. And do Tillandsia (air plants) do not like ground water salts drying on their leaf surfaces (where they take up water).

    To keep Tillandsia healthy many folks soak them in a water bucket each week. Mine have done better for me watering with distilled water mist. At times I do add dilute foliar feed nutrients.

    I know this "rain"water discussion seems a bit off track for a water pH discussion. However, the point is that plant requirements/preferences, water pH, water quality (e.g., dissolved minerals), essential nutrients, and growth media ion exchange surfaces all interact and must all work together acceptably to be successful growing a given plant.

    We also have fish, salamanders, and are working getting frogs established in the ponds that I installed. So I have these water quality versus plant growth considerations to balance also. We don't fertilize the pond plants. We just feed the fish and they feed the plants.

    Indoor Light Garden

    Back Yard Garden & Ponds*

    * We gave a 15'x8.5'x3' main pond with fish and other animals. There is also a 8'x5'x1.5' side pond without fish for tadpole rearing with 'Welcoming Red' classic form Lotus.


    We have a Giant Chilean Gunnera, Japanese Iris and Canna moist bog areas next to the pond for adult frog insect foraging.

    This is a work in progress with things still being installed from pots. The Gunnera will be a large focal backdrop to the pond. Photo taken late last fall just after 5' baby Gunnera tinctoria was installed. I have an 11'x12' growth area for it. Will be tight!

  • garyz8bpnw
    7 years ago

    Perc test for Gunnera bog is shown below. It took 45 min for the free water to drain out of the upper 1' unlined section of the bog pit. A subsoil Gunnera cap was added on top of 50% compost 20% peat mix pit just for the test. The soil cap was then removed and the rest of the pit filled in with the compost/peat/soil mix. Note the moisture path connections to Japanese Iris Bog (unlined in top 1' and liner in lower 1.5') and Canna Bog (not lined).

    The subterranean water pit beneath the Gunnera is 8'x8'x4.5'. The photo below shows it ~half dug to its final depth. It is plastic lined to pool and hold water to support the Gunnera in the bottom 3.5'. The upper 1' was not lined to support water movement through upper soil layer, to flush salts and to stop the pit from "souring" (going too acidic). Water in half of the back yard moves naturally to this low point.

    Background Info

    We moved here a year ago. To a grassy "clean slate" yard. But we'd like as little grass as possible. And we like gardens!

    I quickly learned that our yard is a rocky, sandy, clay glacial till. It is also sunny and dry. So much of my 15 yrs in working with the last shady forest zone yard does not apply here. I must dig beds and pits with an iron rod then shovel, screen out excess rocks and add soil ammendments to support plantings! Depending on plant type, I use 20 to 50% municipal compost.

    I quickly learned about some of the importance of soil pH. We have 80 different hydrangea varieties. Almost all the deep blues and purples shifted to reddish purple to pink! This was due to Miracle Gro bagged potting I used being closer to neutral pH for vegetable and bedding plants.

    One favorite deep blue hydrangea

    didn't completely shift. As the pH effect of the potting soil and compost filtered into the root ball we got a multi effect, showing its entire color range potential. This next season it will be all pink if I do nothing else. And IF I want purple, there is a very narrow pH range for success.

    Thus, I have a massive pH adjustment program underway to get the specific hydrangea color I want for each plant. Altering the soil as much as I have also begs one to check pH and nutrient levels in multiple zones. The water in the pond and boggy areas need testing too.

    I want to master my new yard sooner than later, rather than failing on my time investment. There was a lot of dividing of plant stocks from our last yard to get to this point. And I do not want to have to replace plants.

    Below is pictured what it looks like getting 20 cu yd of "Cedar Grove" brand compost. This is equal to ~495 bags, if you got it at Home Depo, a bag at a time. I'm now on my SECOND load of 20 cu yd, and I might need 10 cu yards more to finish things up. Needless to say, digging in the yard has become a lifestyle lately!

  • garyz8bpnw
    7 years ago
    last modified: 7 years ago

    pH can have a huge effect on hydrangea color. Photos and drawings from internet sources.

    Even 0.25 to 0.5 change in soil pH can drastically alter flower color.

    This is due to acid displacing Aluminum Ions from soil particles and making them more available to be taken up. On the plant flower they bind to a pink colored pigment, shiting the color to purple or even further to blue. If you add lime to increase soil pH the Aluminum stays bound to the soil, it can't be absorbed and thus is not accessible to the pink pigment.

    Obviously adding Aluminum to the soil can assit on helping more Aluminum get into the plant in acid soil, thus giving even deeper blue colors.

  • toxcrusadr
    7 years ago
    last modified: 7 years ago

    Fascinating stuff and a beyond-beautiful garden.

    The interaction of all those ions with plant roots, microbes and soil surfaces is every bit as complex as you say. In grad school for enviro chemistry, I went over to the Ag department and took a course in soil chemistry just to learn more about how soil works, so I could better understand how pollutants interact with it. It also fed my unofficial interest in gardening and composting. Anyway, we had to write a computer program to calculate concentrations of a handful of ions in soil pore water. It's not simple because they all interact, so the concentration of each is dependent upon the others. So basically you had to run the program over and over, using the output of the last run as input for the next. Eventually it would approach steady state (output closer and closer to the input). It was still a crude approximation, just an exercise really, but it drove home how complex the system is.

  • garyz8bpnw
    7 years ago

    I'm a grad school trained Biochemist w Botany (physiology) minor. Mostly worked with mycology lignocellose biodegraders and bioremediation R&D, including some work with biodegradable plastics. Worked quite a bit with shiitake mushroom cultivation and enzymes and biological pulping of wood too. My passion since 12 yr old was growing plants. Mostly indoor orchids. Over last 16 yrs worked to get outdoor gardens at home lush enough to make them feel lush and maybe a little tropical.

    We live on a circle, which limits the front yard size. These are a couple photos of the front yard design going in last summer. With so many deciduous bushes there I have a lot of spring bulbs. Crocus, Hyacinth (50!), small yellow and large Mt Hood daffodil, Poet's Narcissis, Muscaria.

    Along the other side of the walkway are highly fragrant Sarcococca coning into bloom now. In summer the hydrangea will fill on and just touch eack other. The tree rose at 5' now is a nearly thornless 'Zephirine Drouhin'. An heirloom of that's still popular, it's a quintessential 'Old Bourbon' fragrance class rose. It runs 20 - 30'. So, I'm going to run it up the front house corner and also over the front porch.

    Late fall 2016 plant design staging in the back yard.

    Much installed just before first freeze. Japanese Iris Bog is behind the canna on right. Yes, this is the same area above with Canna 'Tropicanna'. On left of walkway are rainbow of German Bearded Iris (not in bog) and modern warm colored Echinacea and Red Hot Poker varieties.

    Japanee Iris, Peruvian Daffodil and Colocasia 'Diamond Head' stage for planting.

    Now much is planted. This is the Japanese Iris Bog (connected to Giant Gunnera bog water pit, but not the fidh pond). Late season with cold nights just before frost makes it look rundown.

    Some of the varieties installed here are below. They are sorted in the yard by increasing height but are random by color. The goal is a mind boggling changing landscape of color. There a other places in the yard with banks of color, such as a fragrant moongarden, where my wife likes to hammock bask in the summer evenings. There's some nocturnal fragrance magicians there such as Brugmansia 'Little Angel, Nicotiana 'Fragrant Cloud, Night Phox 'Midnight Candy', 4 O'clocks and Evening Stock. As you walk there or the wind changes direction, one detects new scents. During the day the Echinacea and Oriental Lilies are quite fragrant too across the yard.

    Then we have Hydrangea with cool blue, white, purple, pink and red colors all around the yard and gazebo edges. Lacking warm yellows and oranges, they contrast with the perennials.

  • garyz8bpnw
    7 years ago
    last modified: 7 years ago

    Typical internet photo for 'Zephirine Drouhin', which is the rose selected for our front entrance area. It's a florabunda that trains quite well and can bloom well top to bottom. It is remarkably shade tolerant too. Has an unforgettable fragance that welcomes you and visitors.

    We've only recently been focusing on adding fragrance because so much of the plants in the yard aren't fragrant. We couldn't miss adding a couple other exceptionally fragrant roses that we have.

    'Secret' (typical internet photo)

    'Jude the Obsure' a David Austin rose with amazing strong fruity warm fragrance. The color may be obsure but not the wafting fragrance! (my photo)

  • toxcrusadr
    7 years ago

    No wonder everyone wants to live in the PNW.

  • garyz8bpnw
    7 years ago
    last modified: 7 years ago

    We are very lucky Gardeners here. So far north but winter more like Gainesville, FL & Northern GA. More consistent rain than CA and lots of mountains with 3,000+ hiking and snowshoeing trails. Can get to mountain pass areas quickly to ski.

    Just remember you don't want to live here, oh no ... because ... um ... it rains too much and Gortex doesn't help at all ... hehe. And there's way too much distraction to gardening.

    Gary and Margo at Coleman Glacier overlook on Mt Baker, WA

  • garyz8bpnw
    7 years ago
    last modified: 7 years ago

    The PNW lowlands works well to grow the Giant Himalayan Lily. We have two varieties, both of which like rich humus ACIDIC soil. These next two photos from our former foresty yard.

    Cardiocrinum giganteum v giganteum (blooms to 14')

    Cardiocrinum giganteum v yunnanense (blooms to 12')

    With the right soil and climate conditions this beauty blooms easy. The Yunnan variety bloomed in a tub the same year we moved it. If it blooms this year, that's 3 years in a row from the clump (it's starting spring growth now and two bulbs in the clump look large enough and ready to bloom. They are pineapple sized!

    <click image below to grow it>

    Our two varieties have stayed 9 to 9.5' so far. So I gotta try a little harder!

  • toxcrusadr
    7 years ago

    Seems a shame to have this photo essay on such a garden buried in a thread on soil pH measurement. :-]

  • monomer
    7 years ago

    Tox... I have a suspicion that this is likely not the only thread to contain these photos? Gary, am I right?

    Buried as it is, I'm enjoying each one and am in awe. Thanks.

  • garyz8bpnw
    7 years ago
    last modified: 7 years ago

    Thx yes I have posted several of the photos in other blogs. I'm from the PNW originally but spent 20 combined years in WI and MN. When I got back home to stay I was blown away by the gardening potential. First 15 years back were in a forested yard where I learned EVERYTHING the hard way about shade flower gardening in acidic soil.

    A year ago we moved to a sunny yard and now am in the learning curve again. I figure why not share to help jump start the success of others, while I learn from them.

    Our house is NOT large or fancy, but our garden will hopefully be interesting.

    We have 80 varieties of hydrangea that we moved with us and 9 kinds of Timber Bamboo for a backdrop. That leaves a foreground for smaller interest plants and larger ones too for contrast with the hydrangea. I'm adding semitropicals mostly. I'm also adding fragrance and to also support tbe local abundance of Hummingbirds, including the large shiny green 'Pacific's that are here year round*.

    I'm growing up seedlings now of 4 O'Clocks, Nicotiana alata, Dianthus 'Rainbow of Loveliness Mix', Night Phlox 'Midnight Candy', Stock and Wallflower to place in strategic zones. We also have 4 kinds of fragrant Honeysuckle, with 'Scentsation' as my favorite (paired with a Clematis).

    * This is how we stop the Hummingbird nectar from freezing during those December/January cold snaps. We plug in any period that we expect freezing weather.

    Wasn't hard to come up with the idea one Christmas as I saw a little bird sitting by a frozen feeder at 17 F hoping the sun would thaw it. Made sense to cheer him up. The nectar never freezes this way nor does it ever feel warm. In a colder climate? Try more wraps. This was a $5 solution. Forget the LED bulbs types, they make almost no heat. The incandescent kind make a little heat.

    FYI Humminbirds get their protein and vitamins mostly from Gnats that they catch when flying. Minerals come also from soil licking. They mostly need sugar to have enough energy to harvest these other resources. Pacifics survive here on Oregon Grape nectar blooming here in Winter. They sort of 'hibernate' at night and when they can't get food by drastically dropping their body temperature. Otherwise they'd starve to death in a few hours. Once we start, we make the personal committment to consistently feed.

  • albert_135   39.17°N 119.76°W 4695ft.
    7 years ago

    When pH was being discussed few years ago the best answers were found at:


    Container Gardening - GardenWeb -