The pH for my potted maples is 7 this goes for all containers with varying planting mediums, some mostly bark some a combination of, pine bark, rock dust, perlite and a little bit of compost. I do not want to add any industrial by products such as aluminum sulfate or sodium sulfite, how about a we bit of some type of go old natural sulfur but what type and how much or is there an easier way. I am looking for a 6.8, and I surely don't want to repot this time of year.
I believe that you are actually trying to lower the pH from 7.0 to 6.8 for a more acidic soil; it seems that you could go lower. How about coffee grounds?
Re:(Lowering) the pH for potted Palmatums? Yes lowering yes coffee grounds maybe I should buy a cheep bag of the un-drinkable type and then just grind them up and mix it in. I have no idea how it go a pH of 7 the rock dust is neutral, the compost is neutral but the pine bark should have been a 6 but it maybe it is neutral as well.
Contact your local espresso/coffee shop; they are usually happy to give away their used coffee grounds. Here in the land of acidic soils, I have not had a need to lower pH, so I don't know how people typically add the coffee grounds. In a pot I assume that you would add a layer on top of the soil and water it in. It seems that your maples are not at risk for harm at this point as you are at a neutral pH, although lowering it is good idea. Perhaps elements in the water there have an effect on pH. It is great that you are monitoring it. Vertrees, in Japanese Maples 2nd ed. (Timber Press 1987), writes:"Extremes in alkaline conditions prevent the maples from performing well. ... The acid type or neutral soils in which rhododendrons do well seem to be suited equally well to the maples."
OK, well Vertrees is saying a pH of 6 to 6.5 is good. I wonder what the pH is on the island of Japan.
I'm not sure your ph is a matter for concern in the first place in containers. The ph in containers jumps up and down - not comparable to the situation in the ground, where ph matters, but palmatums are tolerant to a certain extent: a PH of 7 is pretty good, if not ideal. I wouldn't worry about it in containers. Adding anything to lower the ph might cause other unnecessary trouble. Better to get the right kind of aeration/drainage going, than worry about ph.
OK thanks for that info, as to aeration could we measure that buy how fast a liter of water passes though the medium, per liter of medium, could this be a good premise for quantifying the amount of aeration per amount of evacuation? It could only be thought of as a premise, because there are no supporting statements to conclude an argument(rule). Sorry I don't like typing long hand.
The more often you need to water, the better for the plant - note the 'need to'. If your soil dries out within one day, and you need to water, for instance (before it dries out, of course), you push new air into the soil, and gazes out. Overwatering suffocates the roots, on the other hand. I don't know what you mean by 'rock dust', but if it's all fine particles it's not as good as coarser and more or less uniformly sized particles (say, pine bark pieces of 1/4 inch, with perlite for young maples, a little moisture retentive material added for older plants). Similarly compost is fine textured, and tends to break down fast (i.e. hold water too long). Look for soil mix recommendations in the search engine for this forum. Avoid peat. But your soils look pretty good (except for the 'dust', if that's really dust?) I'd test your soil, see how quickly it drains, whether it tends to wet uniformly (better) or not (not as good). Find out where the water table is (glass container, for instance). Etc. Trial and error, really.
Taking it as true that the Japanese maples will be fine at a neutral pH, why do you think that pH may not matter as much in a container? Why would it be different in a container versus in the ground? I understood that pH is what controls whether nutrients will be available to the plant. For example, at an extremely high pH, apparently the nutrients the maples need won’t be available to the plant even though they may be present in the soil.
Hi, This is a great topic and I just had to chime in. :-) I agree with Schusch in that if your pH is around 7.0 just leave it if your maples are doing well. Maples are okay in neutral soil. Many things affect soil pH. The water you use, organic matter in the soil, what kind of plants are grown, amount of rainfall, etc. Acid levels in the ground tend to fluctuate at a slower rate, being affected most by the amount of rainfall. Since we are talking about potted plants let's talk about what affects pH in the pot. Pure water has a pH of 7.0. Tap water can either be slightly acid or alkaline. Soft water is slightly acidic while hard water is slightly alkaline. People who live in an area with hard water have to deal with lime and salt build up. But, even if your water is hard you may not have to do anything to your potting soil to make it more acid. Organic matter naturally form weak acids as it decays. So, as long as your potting soil has some measure of organic matter in it, as most do, it will tip the pH scale toward acid. It is quite possible that your soil is naturally acid while your water is hard, giving you are more neutral reading on your pH meter. FWIW, I live in Los Angeles and we have hard water. I have never added anything to the water or soil to raise or lower pH outside of what fertilizers I use. You MUST remember that the pH scale is logarithmic and any increase or decrease happens exponentially. Highly acidic soil can cause certain metals in the soil to dissolve. These dissolved metals can kill the plant's roots and/or cause leaves and branches to become stunted and/or discolored. In answer to your soil drainage question: Good drainage doesn't always equate with good aeration. I have been using two different potting soils. The 1st one is a mixture of bark, sand, peat, pumice and composted steer manure. The 2nd one is a mix of bark, forest humus, earthworm castings and crushed red cinder. The 1st one drains very quickly, but the the soil at the bottom of the pot stays quite wet even after a few days. It looks and feels soggy. On the other hand the 2nd mix takes longer to drain. It takes up much more water, BUT it doesn't look or feel soggy at the bottom after the same amount of days as the 1st one. The interesting thing is it's still quite moist and not dried out. As far as what Schusch said about water pushing new air down to the roots, with respect, I have to disagree. I've read the same thing elsewhere online, but I have to disagree. The water simply *displaces* the air in the soil, not push air down into it. You can observe this after potting a plant and giving it water....bubbles will rise to the top if there are air pockets. These pockets that had air in them now have water in them, not new air. Eventually soil may fill in these larger pockets. As the water in the soil evaporates these tiny pockets and gaps fill up with air again. Roots need a certain balance of water and oxygen to be healthy and produce food for the branches and leaves. Too much water and the roots can't get enough air and root rot sets in. If the soil is too dry the roots can't get enough water to rehydrate the leaves which are losing water during transpiration and leaf burn/branch die back sets in. One thing to note: the soil can be moist but not enough to keep the plant hydrated on a warm and/or windy day. One reason I *usually* advise people to try and keep their potted maples on the wet side of moist rather than on the dry side of moist. In other words don't wait till the soil is almost dry to water again. Regards, Layne
I am going to speculate that some of the things we attribute to nitrogen in fertilizers is actually due to changes in pH caused the addition of fertilizers. Things such as leaf color and leaf characteristics, color, and shoot growth are potentially effected. With that in mind, I think a neutral 7.2 to 6.8 or slightly less is ideal. I have heard/been told that keeping the soil slightly on the acidic side can assisiting in keeping the plant healthier and reducing soil-borne disease. I have noticed that some of the organic fertilizers add components like humaric acid and gypsum for pH adjustment. Gypsum being the same component used in many acid plant fertilizers. When we have maples potted we usually use mixes that are highly orgnanic to begin with (fir bark, humus, etc.) and this gives or should give us a slightly acidic mix to start. Further addition of these other acidifying additives might be an issue. While many salts and some nutrients are readily flushed through potting mixes with frequent watering, we have to consider that not all components are freely water soluable once bound in the soil, so we have to be careful what we add. As for the side note about air in the potting mix, I believe that two things that happen in porous mixes when the top layer of soil is open not compact. The initial time that water hits the surface of the soil, the air at the surface of the soil is forced into the mix. Secondly, and this happens much more readily in the landscape, is that as the water flows through the soil a vacuum like situation can be created where air is pulled in behind the water thus aerating spaces the water has left vacant as it has passed through a porous mix. Additionally, we have to consider the air that is mixed in the water or a process of forced oxygenation, where the mechanical process of water striking the soil causes air to be mixed in and this air is carried into the mix. It is not a great quantity, but significant. This process speaks to value of some force being applied behind the water when it is applied to potted maples. I also use a couple of small and cultivators and periodically use them to losen and compacted soil on the surface of containers. Just my two cents and some or a lot of speculation. regards.
In relation to ph and nutrients, I read that nutrients are taken up differently (more readily?) in container situations than in the soil: meaning if a ph is too high or too low for a certain plant to take up this or that micronutrient, for instance, the same ph in a container will not necessarily produce the same adverse result. May be someone can chime in here? This is also what I meant by not overly worrying about the ph in your container soil. My japanese maples in the garden are in a 6.5-7.3 ph situation , and I have not noticed any problems. My acer rubrum, however, seems to struggle with chlorosis - I haven't exactly figured out why, but read the red maple needs a lower ph (manganese deficiency). Finally about the water: it might be a good idea to get info on your tap water, not just because of the ph: in certain areas around where I live the water can be too heavily chlorinated, for instance, which is bad for the plants. I am trying to harvest rainwater for my containers in maples, not so much because of the ph, but because of additives in the tap water. Finally I noticed that three weeks of heavy rainfall here were beneficient to all the trees: I wondered why this has a better effect than watering by hand : more uniform moisture, side effects from the tap water, or beneficial effects from the rain water?
I have a tap water PH of 7.4 but unsure of my pot PH. Say if the soil is slightly acidic as most potting mixes are, won't the constant watering tip the PH to alkaline over time (1-2 years between repotting)? I'd like to prevent chlorosis but the types of different fertilizers are just huge. On one hand I have a general purpose slow release with 7% sulphur and on the other I'm considering fish organic with only 1.2% sulphur. I learned that sulphur helps to keep the soil acidic and therefore manganese will be more available to the plant. I don't like slow release types as the granules get thrown all over the place when I water the plant with watering can. But it has more sulphur compared to the fish organic. There is also specialty rhododenron, camellia and azalea slow release but strangely they only have 2% sulphur. Please let me know which type is the best!
Back on the coffee grounds suggestion, just about every Starbucks near me has a "grounds for the garden" box in which they put bags of used grounds free for the taking. An organic suggestion not mentioned and one that I use to help with acidity is cottonseed meal. Though at about 6-1-1 (or 6-2-1) the trade off is your adding a bit of nitrogen.
Oh, and cottonseed meal is very inexpensive. You should be able to get it at just about any livestock feed store.
My water is hard and therefore alkaline so I have lately been taking advantage of the Starbucks free grounds. I decided it was something that would be organic, a pretty harmless additive to my soil mix and maybe would just offset the water, since most of the watering in pots comes from my tap. I throw one big bag into my mix which about fills my wheelbarrel. I haven't ever tested my potting mix, that might be something to do, I guess. I also dump bags around my maples planted in the ground. I can't say I notice any difference. It smells good :) I did throw some on a potted fern I had in the growing in the house and it seemed to perk up. Kay
