Testing PH and what to do about the results.

[davidwood]

I hope what I say makes sense and I would welcome any observations and advice. Having read the HVI care CD I decided to buy a good PH meter. Now having done some test over 2 days I have had some strange results and am not sure quite what to do.

Charles says for best results the ideal PH is 5.8 to 6.2.
My plants from morning through to night have a  range from 4 to 6.8.I am not exactly sure why there is such a big difference between each pot but there is.
I will say that I am fairly confident about the meter, it’s been very consistent, pots that have read high have stayed high and pots that have read low have stayed low, and as I mention later all have a much higher reading in the evening.

Well the first problem I have is my coco coir; its PH range is between 3.5 and 5, so depending on what % is in the pot seems to determine the PH in that particular pot which in general is to low.
Now unless Charles says otherwise I will mix more worm castings to the pots with a very low PH and add coco coir to the ones with a high PH, is this good practice?

The second problem is the quite dramatic change in the PH from the heat of the day to the slightly cooler evening and how if at all will this affect the feeding.
For example if I read what Charles is saying it would be better to feed Acapulco Gold in the afternoon when its PH is 6.2 rather than the evening when its 6.8 and vica versa with Purple Hat Society where the PH is very low in the morning 4.5 and much higher at night 5.4[I will be adding worm castings to Purple Hat to bring the PH higher].

The reason I have gone to all this trouble is I am not getting nothing like the results from my cv’s I expect, in fact since I have gained knowledge about the right soil watering and NPK I have gone backwards, my blooms are getting fewer and smaller ha ha .I now have a water test kit on the way and I hope the water I am using is ok.

Please if anyone can make sense of the above please tell me.

[Charlie]

David, you've asked a lot of questions that cover a lot of material here. Sometimes it's best to go back to the basics, particularly when your observations are not making sense to you.

Here are some of the questions that come to mind for me. Without good answers to them I can't go much further with sorting this out. OK, here goes.

How are you doing the pH test? You should be using the slurry method, and using pH neutral water to do it.

pH measuring is temperature dependent. Some meters have automatic compensation for temperature, and others do not. Since your temps are so extreme in Vietnam this probably matters.

Is your coco coir really coco coir? It should not have a low pH. The more common potting mix material - peat moss - has a very low pH and needs to be carefully amended with limestone prior to use. If you are sure you have coco coir, and it is showing low pH, something is wrong and I would guess that is with the measuring of the pH.

Are the temperatures there stable or going up? Hibiscus are very sensitive to temperature. That is why hibiscus shows are almost all scheduled for spring or fall. As temperatures go above 95F (35C) flower quantity and quality go down. Special care such as providing some shade and watering twice a day so that there is no water stress in the late afternoon can help compensate for these higher temperatures. The flowers of some varieties are more heat resistant than others. For instance, John P who lives in central TX has good results with Bridal Path but terrible with Magic Moments. Often it is a matter of figuring out which varieties work best where you live.

In high temperatures hibiscus draw a lot of water in through the roots. Fertilizer comes with the water. It is possible to over fertilize hibiscus in high temperatures because they use so much water at that time. You should not have any issues with lack of mineral nutrients in such conditions unless the pH and/or alkalinity is way out of normal ranges. Are the plants green and growing? That gives you a good indicator of the overall health. Flowers are optional for hibiscus. When conditions are right they make them but if they are stressed they stop making them.

What does all this mean? Well, back to basics. The soil they are growing in is important. Hibiscus are quite tolerant but if you go outside the those tolerances there can be problems.

The amount of water they get is important. Whether that water is evenly provided or whether they are going through flood and drought each day can also make a big difference.

Nutrients are important and if in doubt just feed 1/2 teaspoon per gallon every day of HVH Special Blend in hot weather. Supernova is a stress reliever for hibiscus and can be used also at 1/2 teaspoon per gallon every day in hot weather. 

I know it can be complicated but stick with the basics and it should help. Instruments like pH meters can be helpful but only if they give accurate data. That requires some practice and learning how to take the measurements properly. Most meters need maintenance and regular calibration, too.

Charlie

[davidwood]

Wow!!! Thanks Charles, I think I need you to come here for a holiday ha ha.Problem for me now is your answer as posed me more questions in my quest to find out what is wrong.
But before I talk about the PH one thing having this meter has shown is I am massively over watering.
On Sunday night I give them a big watering till 10%water was running out the pots and they have only started to dry up now on Tuesday evening and then not enough to panic[leaves look fine] so will not water till Wednesday morning, a total of 60 hours. Normally they would have had 4 big waterings and a top up or two in that time, so maybe I have been keeping the roots saturated which cant of helped. I have followed your advice on the HVI CD and the plant is now going to tell me when to water not just because I feel hot and the surface is dry [it’s a constant 90f and very humid 24/7 at the moment], and most important of all is the plants all look extremely healthy, which luckily they do. In fact if it wasn’t for the tiny blooms [Acapulco Gold 4 inches Night Magic 3 inches ect] everything would appear fine.
As for the PH maybe the meter is not accurate enough to be exact, what is consistent though is the cv’s with very dark green leaves show a higher reading than those with pale leaves and a pot of just coco coir is the lowest of all.

The truth is Charlie I have never seen coco coir in a brick like you see on the Internet, they say at the shop its coco and it certainly comes from a coconut that’s why its so cheap, one dollar for as much as you can carry, they call it coco peat and it consistently measures low with this meter so I will have to have a think about that, the problem is the alternative seems to be clay and that measures even lower.

[Charlie]

Hi David,

It's surprising to me that the water in your pots is lasting several days at 90F. Perhaps the high humidity is slowing the rate of transpiration (like perspiration for plants) or else you are using really big pots. Anyway, it's good that you found out and are making adjustments, just don't go too far the other way!

Coco coir or coco peat as it is sometimes called, has been widely reported to naturally have a pH of between 5.5 and 7.0 with the typical specimen in the 6's. If the pH of your coco is really lower than that there is something going on that you should try to discover. Coco coir is the by-product of removing long fibers from coconut shells to make all sorts of things. What is left over is the pith and shorter fibers and these were considered waste until someone figured out they make good growing media.The factories that do this fiber removal have various techniques to do so and often the coir has to be cleaned by rinsing and flushing to remove salt and other contaminants.  If you soak and rinse 3 times you will remove most problem contaminants and you probably should do that before using it.

Keep us informed of what you observe and do. It is very interesting to hear of your growing adventures in tropical place with few of the materials we have come to rely on available.

Charlie

[davidwood]

Charles,i will certainly let you know how i get on and the water retention was a big suprise to me also.I have sent you a picture and it shows how i have 90% of my cv's potted up.They are all in 8inch thick plastic pots then placed in a larger ceramic pot and insulated with clay and sand,so with the leaf canopy the pot receives no direct sun.

I have been working it out and it looks like i need an average of 1 pint per day per cv,even then that is still keeping them very moist.Up until now they have been getting well over double that so i am very interested to see what results this change will bring.

[Charlie]

That was a smart way to do the potting up! Keeping the roots cool and surely less evaporation from the pots. Thanks for the photo.

Charlie

[davidwood]

Charles i said i would let you know how i was getting on so here goes. So far it is amazing,i have buds all over the place,yesterday Night Magic bloomed at double its last size and i have had my first 7inch and 2 day bloom with Chariots of Fire,Acapulco gold has a bud and its the size of a plum ha ha.
Now i know the temperature has dropped to about 85f, but it has to be the water,by using the probe i have reduced by about 70% what they where getting.
I also made another discovery.I took your advice and when i made up a large bucket of coco coir i washed it 3 times,i then left it 10 days ago down the bottom of the garden[in the sun] in readiness for when my 6inch plants come,its still wet.
I just hope that the coco having such good retention is a good thing,please let me know,the reason i worry a little is that the 4 inch plants i last had,allthough growing well i have not watered so therefore not fed for a week.

PS.Acapulco Gold has just opened[typical my camera is in the shop],no wonder the bud was so big its opened as a cup and saucer and not a single.

[Charlie]

Hi David,

I happened to read something about coco coir recently that gave another reason to wash your coco coir before using. This info came from a grower in The Philippines who uses the native coco that is a by-product of their coconut industry. That grower claims that the coir contains some acids that need to be washed out. In the past I've heard it was the salt contamination from the sea that needed to be washed out. If indeed there are acids on such coir that would explain your very low pH readings. This grower said they wash the coir until the color of the water that drains out of the coir becomes clear (at first it is red). At that time their coir is considered pH neutral and free of acids.

Each growing location has its own microclimate and some things will always be different in different locations. However, I have to tell you that when temperatures go under 90F hibiscus flower wonderfully well everywhere I know about, and when temperatures go into the high 90's flowering suffers and the plants need a whole lot more water. I am not expecting good things to come from lowering the amount of water for your hibiscus. It may be that you potted up a lot of plants into larger pots than they had before and for a short time that will provide excess water due to the extra potting mix with no roots penetrating into the mix. The mix serves as an additional water reservoir when that is the case. However, as soon as the roots grow through the new mix and the plants get a little larger the amount of water may need to be adjusted upwards. Stay alert to changes and be ready to turn back on the tap if you observe plant stress is my suggestion......

We'd love to see more photos some time!

Charlie

[davidwood]

Charles you could not be more spot on,when i washed the coco i had a river of red water through the garden,also the temperature had dropped from an average of 95f to about 85f[there is never a difference in the evening] and after washing the PH was much higher,so maybe this is the reason as you say for the good results i am getting.
I understand totally about the water but i don't think you know how stupid i have been,because i read that 10% of the water should run out the bottom of the pot i have been doing that twice a day and the odd top up in between,the plants where permanently waterlogged!!!.Now i check every plant about 3 times a day and just make sure they are nice and moist,ha ha so a 70% cut in water is not as drastic as it sounds and they are probably still getting more water than average.

[Charlie]

All that sounds good, David. It's great news that you are getting more and larger flowers now. I look forward to hearing what happens next!

Charlie

[davidwood]

Charles,i have found out what is wrong with my plants and i am surprised i have any left alive.Yesterday i went down the garden shop to get some pots.There i saw a red hibiscus,which is a clone of the one i have and what first got me started 2 years ago,difference being that looked lovely and mine half dead.I inspected the soil and find out its half clay half sand with other bits and bobs,anyway i thought sod this i am going to re-pot some of my cv's back into clay,this coco does not seem to be working,big decision for me as i try to follow word for word what you have written on the CD.

I will try to explain what happened,when i went to re -pot,i tipped the pot upside down holding the trunk between my fingers like you say and everything just fell out and i was left with the cv and the roots sticking up into fresh air.I had a hellave shock,basically the roots aren't grabbing or sticking to the soil,i went to another cv gave it a gentle tug and i just pulled it out with ease,they look like something bare root you would get in the post,i don't know how they are still alive or whats gone wrong.

Anyway for the last 18 hours i have re-poted the lot into sand clay worm castings perlite and some Bounce compost pellets NO COCO and lots of Super Nova.,allready some are looking better.

When do i start a fertilizing?,do i have to wait or should i start now.

[davidwood]

Charles i had another shock today,i said i had re-potted all my cv's using clay,well its certainly not clay.When i bought it a few days ago it was premixed with sand and that's what i assumed.Today i needed some more so bought a bag not mixed and had a shock when i picked it up,it was so light.I tried to ask the lady what it was and she just shouted at me and pointed to the ground,i cant speak Vietnamese.Whatever it is all there plants and trees grow very well in it so it must be okay but i am now trying to find out exactly what it is.
The best way to describe, its very black and feels like ash,and when you water a pot full you are left with less than half a pot.
I will let you know when i find out

[jpiper82]

David, Save yourself some time and agony, just buy HVH potting soil, freight is a killer, but I have peace of mind.
Best Regards,
John

[Charlie]

David, you are on quite a mission of discovery over there in Vietnam! I can't quite figure out what is happening. Eventually you need to settle on a potting mix and give the plants a chance to root completely in it - give them some of that good old benign neglect and see what they do. I don't mean stop waterting and feeding, just don't make major changes too often.

Cindy tells me you just ordered some mix from us. That will do it but it would be convenient for you to find a local supply of something that works. I think that once it is well washed the local coco coir would be ok. Why did you back away from that?

Charlie

[davidwood]

Charles if you go back  5 posts you will see why and what happened.I thought you had missed it,very unusual for you not to answer straight away,and am still not sure when to start re-fertilizing after re-potting.In a nutshell my roots weren't binding to the mix.

John i have allready asked Cindy about the cost on shipping, but i might just go along with this mix now and am just  very pleased that at last i have found out what was wrong,in a period of 2 days i have seen huge improvements in the ten plants that had a problem.
The truth is if i had not found out the problem i would have given up,to be doing everything by the book and have 2 inch blooms was driving me crazy and to re-pot the lot with HVH would cost me over a thousand dollars in shipping.So hopefully within a few months i will have some photo's to match yours.