San Pedro yellowing

[other peoples pubes]

One of my San Pedros has turned a bit yellow this week.

I live in Newcastle & we have had heaps of rain this lately, and I have left them outside as the guy I got them from said they cannot get too much water.

I was wondering if this is true, and if not is it a big problem. I can post photos if needed.

Thanks for the help.

OPP

[bit]

I think it's a combination of lots of water, and lack of light that turns them yellow. Bear in mind we are approaching the shortest day of the year. Trichs are pretty resistant to root rot, so if it's in a well drained pot that shouldn't be a concern. It'll bounce back. Woudn't worry about it too much.

[other peoples pubes]

thanks mate, sounds good

[M S Smith]

I don't know how much rain you get, but the city I live in gets more rainy days per year than Seattle, Washington, and my plant never have problems with rot, they especially never turn yellow from too much water. I've had nearly two weeks of continual rain before and had no troubles at all. Yellowing is more due to excessive sunlight and/or poor nutrients. You'd be suprised how well these plants can grow in just a few hours direct sunlight with the rest being diffused light.

~Michael~

[Micromegas]

Hey OPP, my plants are in the ground basically outside in a paddock (i.e absolutely no shelter from the elements) and as winter prgresses I'm finding many of them to be yellowing too, I'd say a combination of moisture, consistent cold and some unusually heavy frosts as well as poor soil are probably the culprits and many of my succulents are turning up their toes. I've found the middle of winter and the middle of summer to be bad for their appearence, autumn and the beginning of spring to be the best. Also the tightening of the skin from water uptake seems to stretch the colour a bit if you know what I mean, less green to go around. I don't know if that helps I'm just venting cause of all the weeds I can't find time to remove, and i'd rather have my pedros looking as healthy as possible, but alas. The pedro seems more prone to yellowing than other varieties of cacti too, interestingly.

Micro

[bit]

Yellowing is more due to excessive sunlight and/or poor nutrients.

Not sure about this one, I certainly don't think it's the only reason? I've had three experiences now, where moving yellowing plants from 'outside' in the winter/spring rain into mini greenhouses has caused them to green up within a couple of weeks. During this time I haven't changed anything, except allowed them to dry out a bit, and be a little warmer. The amount of sunlight and nutrients has remained identical. Two of these were pachanoi, and one cereus.

[M S Smith]

Bit, if you had to bring the plants into the greenhouse due to seasonal rains then "the amount of sunlight" can not have "remained identical." Are you suggesting that if you had brought the cactus into the greenhouse and watered with as much water as they were getting in the seasonal rains the plants would have remained yellow?

I wonder about UV levels on cactus, how it might effect chlorophyll production, and to what degree different greenhouse materials alter or block natural UV radiation. Anyone have any ideas?

~Michael~

[bit]

Bit, if you had to bring the plants into the greenhouse due to seasonal rains then "the amount of sunlight" can not have "remained identical." Are you suggesting that if you had brought the cactus into the greenhouse and watered with as much water as they were getting in the seasonal rains the plants would have remained yellow?

I wonder about UV levels on cactus, how it might effect chlorophyll production, and to what degree different greenhouse materials alter or block natural UV radiation. Anyone have any ideas?

~Michael~

Hi MS, the reason I put the plants into the greenhouse was that I was concerned about their yellowing state. I had tried a couple of doses of fert, and they didn't seem to be improving over about 4 weeks (much of the fert may have simply washed through the soil though, as the weather was fairly wet).

The greenhouses I have are small, plastic covered sorts, only a metre or two square. The plastic cover is transparent, and it's a polyurethane type material that you can fold up easily if you dismantle it. They are sitting on my deck, so the amount of sun is literally identical inside vs outside. I can't say whether watering while inside the greenhouse would have had an effect on their colour or not.

Here's a theory though.

The cereus I mentioned, was very yellow toward the end of spring last year. When I put it in the greenhouse, it put on about 30cm in 5 weeks having been completely dormant for months prior. The new growth was very glaucous etc, but the old part remained yellowish. Growth continued throughout the summer and it looked very nice, right up until about 4 weeks ago, when the weather here turned cold.

Today, the whole plant has gone back to yellow (it's still in the greenhouse), and seems to have lost all the lovely glaucous colour it had prior. So, my theory is that temperature has a big role in this too (although other plants don't seem to have been affected in quite the same way, perhaps cereus is a little less hardy).

[planthelper]

they turn yellow because there roots are not healthy, rootrot from too much water and a weak root system caused by what ever other reasons (too dry, bad soil...) will produce similar symptoms. go and inspect the rootenviroment, i bet you the roots look weak and unhealthy. chances are that an unhealthy rootsystem will not ever become realy healthy again, sure sometimes they recover a bit, but still this would be a far cry from, how strong and healthy they could grow. so it's better to cut some sections and re root the pedros.

yellowing is often associated with dense, non friable soil, or potting mix.

so change your pottingmix and make sure it's well airiated.

i have often observed yellowing aswell with specimesn of pedro in it's native location, what seems to happen is described as followes. i think pedro sometimes "aborts", parts of it's structure, because of bad conditions, in other words, one can see a pedro which has 80% of it's collums nice and green, and the rest turned yellow. the cacti simply refuses to support and give energie to a lost cause, but is still green there wher the soil hasn't been exhausted yet.

but even this yellowing, has it's good sides, as after a few years the collum will topple over, and the still green tip will land a few metres away from it's original host, where it will encounter fresh (not yet exhausted) soil and evantualy form a new plant.

so it makes sence to reshoot the still green tip, which is still green as nitrogen is highly movable within the plant.

[bit]

they turn yellow because there roots are not healthy, rootrot from too much water and a weak root system caused by what ever other reasons (too dry, bad soil...) will produce similar symptoms. go and inspect the rootenviroment, i bet you the roots look weak and unhealthy. chances are that an unhealthy rootsystem will not ever become realy healthy again, sure sometimes they recover a bit, but still this would be a far cry from, how strong and healthy they could grow. so it's better to cut some sections and re root the pedros.

yellowing is often associated with dense, non friable soil, or potting mix.

Hey planthelper, thanks for the help There are obviously many reasons they can go yellow, as yours doesn't bear my experiences.

[Auntyjack]

Bit, ave you git a pic?

AJ

[bit]

Spot the yellow pedro on the right. Check last pic to see it after it came right, but it only took a couple of weeks in my greenhouse to come back to full green, and has been good right through the summer/autum.

This is my CPM when I go it:

And during the winter while outdoors:

And 5 weeks after moving into the greenhouse:

Also note the tall pedro here, pic taken shortly before moving into greenhouse (only _just_ fit), which also came right within a few weeks:

[Micromegas]

Hey bit, thanks for the photos (nice plants too btw), i definately think there are a range of factors involved in why cacti (and pedros in particular in my case) turn yellow and I look forward to seeing how my plants develop over the next few years. Definately the elements play a huge part in the colour, as evidenced by the fact that many of my plants are lighter green to yellow on one side and darker on the other, the lighter side being the side that faces in the direction of the most inclement weather. Soil must also have a role to play; my plants are arranged in a circle more or less and some 'areas' are more prone to having yellow plants than others, perhaps due to different soil ph or quality. Definately root structure has a role to play too, as a yellow pedro i moved last autumn greened up nicely in its new location, and some that blew over while I was away have had a hard time recovering (others have recovered fine). Time of planting (winter is bad!) and parent plant also seem to be important, and mid-section cuts seem to have a tendency to go lighter green/yellow than tip cuttings, as well as old-growth cuts from large plants which are generally lighter to start off with. One plant that is particularly yellow flowered (4 flowers) at about 30cm and hasn't seemed to have recovered yet from the effort, strange. All my plants are less than 2 years in the ground, but the difference in colour and growth pattern/speed, profusion of pups (some pupped from almost every rib, some have no pups) when the conditions have been more or less uniform is interesting to say the least. I'm glad your plants greened up again, it certainly looks better than the yellow. Definately pedros in the wild often look yellow, especially those growing along cliff faces, in wetter areas they can be the most magnificent blue; it really is amazing how they propogate themselves.

This is interesting guys I'd love to hear more thoughts about the yellowing of cacti, overall the trend has been that my plants got very green at the beginning of autumn (first rains) and then yellowed progressively since then with more rain and frost. Obviosuly the darker green they were to start with, the better they have handled the cold. The biggest ones go yellow-er in the main column and send out glaucous to dark green pups.

Micro

[planthelper]

the one specimen which recovered nicly during the time in the glasshouse, tells me that it's a nutrient deficancy.

the more strong light plants recieve the more nitrogen they need to cope with this condition, thats why they recovered indoors. aswell the observation that the, sides of the cacti which face the most light are paler than the opposite side, seems to support this idea. aswell, it might be said that soggy soil conditions make it hard (or even close to impossible) for cacti and plants to absorbe nitrogen (and proly other nutes aswell?), i think to remeber it has to do with lack of oxygen or air in the soil. that means that even ferting might not help, unless the soils is friable.

personally, i think that gravel pebbles on top of the pottingmix can be quite often a bad idea, as it might cause a waterline, meaning the soil splits into very dry and very wet layers, instead of an overall moist, loose and friable condition.

the same happens often if people add gravel to there potting mix in an unsuitable fashion, you can see if that is the case with your plants by simply taking them out of there pots. if you are afraid of taking the pot off because of damage caused to the plants, then it means that the roots were crap anyway and as i said in my other post, it's unlikely they will heal and get strong.

[devance]

Look fine to me.

If turning yellow a bottom root rot.

Have to cut off the bottom and very much to do a thinking of a soil which is not H20 retainer as far as soil but can get the nutrients very fast. As a fast flood from rain.

For San Pandro just landscaping bark is good for water in a pot with added chemical fertilizer.

Just doing that is more than a fast growth.

When turning yellow theres no roots.

[Micromegas]

Thanks planthelper soil quality is definately a key issue and my soil is certainly far from good quality...

the more strong light plants recieve the more nitrogen they need to cope with this condition, thats why they recovered indoors. aswell the observation that the, sides of the cacti which face the most light are paler than the opposite side, seems to support this idea.

I don't understand why the colour wouldn't be uniformly yellow if it was purely a lack of nutrients, as opposed to a dimming of skin colour over time (like cloth that fades in the sun, or in the wash).

But once winter has passed on I'll be digging a few up and examining them, inproving the soil, fertilising etc. hoping that the factors involved in yellowing cacti is only external is wishful thinking on my part.

Thanks, much work to do when the days are warmer and longer!

Micro

[bit]

the one specimen which recovered nicly during the time in the glasshouse, tells me that it's a nutrient deficancy.

the more strong light plants recieve the more nitrogen they need to cope with this condition, thats why they recovered indoors. aswell the observation that the, sides of the cacti which face the most light are paler than the opposite side, seems to support this idea. aswell, it might be said that soggy soil conditions make it hard (or even close to impossible) for cacti and plants to absorbe nitrogen (and proly other nutes aswell?), i think to remeber it has to do with lack of oxygen or air in the soil. that means that even ferting might not help, unless the soils is friable.

Your logic there still doesn't hold up. If you read above you will see that my plants get exactly the same amount of light in or out of their mini-greenhouse, as they're in exactly the same position. They are not yellowing on just one side either, it's the whole plant. The only thing which makes sense there is that the plants have more difficulty extracting nutrients from over-wet soil. In which case drying the soil can fix the problem, and it's not necessarily poor quality soil, just too wet soil, especially if they improve when dried out.

personally, i think that gravel pebbles on top of the pottingmix can be quite often a bad idea, as it might cause a waterline, meaning the soil splits into very dry and very wet layers, instead of an overall moist, loose and friable condition.

the same happens often if people add gravel to there potting mix in an unsuitable fashion, you can see if that is the case with your plants by simply taking them out of there pots. if you are afraid of taking the pot off because of damage caused to the plants, then it means that the roots were crap anyway and as i said in my other post, it's unlikely they will heal and get strong.

Can you please explain this 'waterline' business in a bit more detail, especially how it might be created by rock on top of the soil? Cheers.

[planthelper]

Your logic there still doesn't hold up. If you read above you will see that my plants get exactly the same amount of light in or out of their mini-greenhouse, as they're in exactly the same position. They are not yellowing on just one side either, it's the whole plant. The only thing which makes sense there is that the plants have more difficulty extracting nutrients from over-wet soil. In which case drying the soil can fix the problem, and it's not necessarily poor quality soil, just too wet soil, especially if they improve when dried out.

i threw in various logic's, and as you say in your case the wet soil might be the major cause and i mentioned this one, but that doesn't mean that what i said about if a cacti stressed for nutes recives less light, and turns more green, doesn't hold up...

Can you please explain this 'waterline' business in a bit more detail, especially how it might be created by rock on top of the soil? Cheers.

imagen your pot, now fill a layer of gravel in the bottom, than a layer of a good waterholding pottingmix, than a layer of gravel, and than the waterholding mix again and so on. or just like in your case a single layer of gravel on top of some potting mix. now you water and everytime the gravel will dry up fast and the pottingmix will stay moist, the gravel is hydrophobic, and the potting mix will stay moist. over time this will exeggerate the specific properties of each medium.

another factor which might play a role here is the edge effect, the water will be attracted to the edge between those two different mediums.

at times when repotting i observed, that some areas of my root ball where very wet, whilst areas right next to it were bone dry!! and this is caused by mediums of different properties, sharing the same space.

it can even happen if you water your plants in a fashion which makes the top dry out repeatedly, but let's the bottom stay moist everytime. like this, even though the whole pot is filled with excactly the same medium, the top will evantualy become hydrophobic and the bottom layer will become hydrophilic.

needless to say that, the roots of plants hate this sort of conditions.

[planthelper]

hmm, i lost the first part of my post...

regarding to my logic not holding up:

i simply offered several explanations, soggy feet was one of them. regardless it's a fact that the more light a plant has to endure the more nitrogen it will need, it might not be apropiate in your case but probably came handy for other readers, cheers!