Can you help with options to lower soil PH? Some of my plants are suffering from what I think is chlorosis and I thin my soil is on the alkaline side. I was thinking Sphagnum Peat but then read that soil tends to revert back to its original PH anyway. I like Epsoma products and their Garden Iron contains 22% iron and 55% sulfur. Wouldn't the iron correct the chlorosis and the sulfur lower the PH? Could I use that even if the plant is not suffering from chlorosis, if I just wanted to change the color of the hydrangeas to blue?
Amending soil to lower PH
The first thing I would do is check your soil pH...just because you think it's alkaline doesn't mean it is and I really wouldn't want to try and adjust your pH without knowing for sure--soil that's too acidic isn't going to be good either. If you've got evidence like your macrophyllas all bloom in a nice pink then that's a more sure sign that your pH is a little higher, although before you start amending it's still good to know exactly how high, otherwise you won't have any idea how much amending you need. If your plants that you think are chlorotic are acid loving plants like azaleas, etc then that could be your problem and making the soil more acidic is probably worthwhile, but most perennials and things can tolerate a range of pH's so whatever's happening with your plants is more likely due to something else other than soil pH (unless your soil is extremely alkaline).
If your soil is indeed alkaline, you are going to have to amend it on a regular basis since things will tend to drift back to their natural state. If you're only off a little from where you want to be then it may not be too much of a struggle to keep it where you want it, but if you have extremely alkaline soil then you may find it easier to find plants that are OK with higher pH rather than constantly fighting to make your soil something it's not.
As far as your Espoma product--iron can only correct chlorosis if the pH of the soil is low enough, if the pH is too high then the iron isn't in a form that the plant can take up. And the sulfur will act to lower the pH, but given that you're probably not adding a ton of this stuff, I'm not sure how big of an impact you're going to see on the soil pH, you'll probably need to do something else as well if your soil is pretty alkaline. So the same thing goes for turning your hydrangeas blue--if your pH is not that far off then the sulfur in the product might be enough to turn them blue, but maybe not. Sulfur on its own is one amendment that can be used to acidify the soil--I'm not sure how much iron you want in your soil though so it might be better to find something that just has sulfur.
Thanks ecrane. I think I have a home soil test kit here somewhere. I'll dig that out and start with that. I think it would be worth it to send some soil samples to the county extention. I would think I would have to take multiple samples from different planting areas? I've got 2 Azaleas that have slowly been going downhill for years. They keep hanging in there but are down to almost no leaves, and what they have a yellow. I really do suspect the soil is alkaline. Those are my Nikko Blue that I posted for Luis and even those are barely blue. Anyway, I'll check the home kit and go from there, thanks again.
bbinnj -
If you check here about my water PH question, raising the soil PH... yes, I did check the water with the PH strips we use for our fishtank. The PH came out 8.4 and the strips also measure the overall alkalinity of the water which was 240. I don't know much about water chemistry except what I know about pool water which is if your water alkalinity is high, it's hard to keep the water PH down on the neutral side. They work together somehow I suppose.
I was reasoning that if you are watering with high PH water that is getting into the ground soil and also being taken up by the plants themselves, but of course I could "be all wet" on that theory. Ooooh, bad pun huh?
Can you tell us what the plants are that you are having problems with, or maybe post a picture? And getting your soil pH tested would still be a good idea too--I suspect that your soil is probably a little on the alkaline side, but I'm not sure that it's so alkaline that it would be causing problems for anything but azaleas and things like that which need acidic soil. There are so many other things that can go wrong with plants, especially if you have a number of plants that are having problems it's more likely related to watering, or poor soil, lack of fertilizing, something along those lines vs a pH problem.
ecrane - I finally soil tested yesterday. This soil test runs on an ABC basis. C being everything is normal for nutrients. A, lacking nutrients. I soil tested three different bed areas and they all came up the same. I tested 6" down and the soil was nice and black but clumpy clayish.
PH - 7
Nitrogen - between A and B
Phosphorus - C
Potassium - less than A (yikes!)
Mainly, it's the azalea and the phlox that look poor and I'll post those pics. Last year both the Pink Beauty and Nikko Blue Hydrangea suffered chlorotic looking leaves (Pink Beauty this year is getting yellowing in its leaves too, picture is following.
Here's Paradise Blue Phlox that never bloomed blue. This plant has never grown since planting in late '06
Another shot of the blue phlox
Last one, the Pink Beauty Hydrangea leaf
I'd flip the leaves of your Pink Beauty over and check for spider mites--it could just be chlorosis, but it could also be the stippled yellow pattern that you get with spider mites. They're very tiny, so just look for teensy brownish or reddish dots on the undersides of the leaves, and if you do find some make sure you inspect and treat any plants that are in close proximity since they spread very easily. It probably isn't that, but I just had SM's on one of my hydrangeas and the leaves looked a lot like yours so it's worth checking. Your pH is on the high side for the azalea, but hydrangeas and phlox should be fine at that pH. But if your soil is a bit low on nitrogen which it seems like it is, maybe it could use a boost of fertilizer (lack of nitrogen could cause leaf symptoms, and also since nitrogen stimulates green growth, if you're low on it that could be why things like the phlox aren't growing as much as they ought to) I don't see any symptoms on these plants that are consistent with potassium deficiency, but since your soil tested as deficient in it and most fertilizers come with N, P, and K in them you'll be adding some anyway when you fertilize. (I would try to find a fertilizer with a lower middle number though since you already have plenty of phosphorus)
Thanks ecrane. How often should I fertilize? It would probably be the slow release organic so could I do that now and Sept 1st and then stop? And then should I do it monthly starting in Spring and then check the soil periodically until improved?
Hopefully someone from your zone will have some advice on how late you can fertilize, but I worry that September might be getting a bit too late in the season. In the spring, the frequency is going to depend on the type of fertilizer you use, if it's a controlled release one sometimes those aren't supposed to be used more than once every few months or more depending on the brand so make sure you check the label. One other thing you might consider is getting in a good load of composted manure or something along those lines and put that over your garden, that'll work to improve your soil too.
Thanks again. I've had a post on soil and composting so they've got me working on a nice pile of compost for next season and I'll work on that and use it come Spring. Thanks for your help here.
Ecrane, that question might be silly but I always wonder! I have hydrangeas and delphiniums (whcih thrive on alkaline soil) on the same flower bed. How do I handle that? When I planted of course I didn't know about that...should I just ignore it or is it the case for taking action?
Hydrangeas don't need acidic soil, they'll do fine in slightly alkaline soil as long as you don't mind having pink blooms instead of blue (or grow white ones or arborescens and paniculata which don't change color with pH). If the pH starts getting too high then they won't be as happy, but I suspect you can keep the pH in a range that's just a little alkaline and both the hydrangea and the delphiniums ought to be happy. But if you really are dying to have blue hydrangeas then some moves might be in order.
Thanks ecrane! The hydrangeas by the delphiniums are white. But I do have another one that is blooming totally pink instead of blue! But I don't want to add chemicals to the soil just for the sake of color you know? As long as they're healthy, I'm happy!