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 Shrinkage

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Cactusero incipiente



Number of posts : 5
Age : 29
Location : Mexico
Registration date : 2011-01-11

PostSubject: Shrinkage    Wed Jul 13, 2011 5:29 am

Hi. I'm from Mexico City and, as you may know, central region of the country has a rainy summer, so the weather is not so hot during these months as in spring.

I have some indoor Mammillarias that are presenting shrinkage phenomena and I'm a little worried about them. I have read in some forums that shrinkage is due to lack of water, in other ones they said is due to overwatering. I am a llitle confused as to what I must do with them: should I water them or should I let them dry? As I said, climate it's not so hot as in spring, so I'm not sure about the lack of water. If the temperature went down since the start of summer, why should they have dehydratation? The opposite, overwatering, neither convinces me thoroughly: the Mammillarias are not swelling up, stem is not splitting, no rot, etc. I was considering some kind of pest in roots, but they are fine (it could be strange since they are indoor Mammillarias). Some people have told me shrinkage is normal, but I perceive it is not cause they don't look pretty well. What could it be the problem and what should I do?

The Mammillarias that are in this condition are M. carmenae, M. plumosa (this is the worst one), M. herrerae , and M. elongata. I tried watering M. plumosa two days ago, nothing happened to improve its appearance.
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woltertenhoeve



Number of posts : 226
Registration date : 2009-10-01

PostSubject: Re: Shrinkage    Wed Jul 13, 2011 9:25 pm

Hola Jonathan,

I do not know how much light and how much warmth your indoor Mammillarias get, but if you do not grow them in a greenhouse then it could be that they might need some more warmth and light. If they are in a too cool position, then they may stop growing and shrink. How warm does it get indoors where your Mammillarias are?
Other questions: How often do you water them? If you water them (soak them completely), how many days does it take before the soil is almost completely dry again? If the soil is still very wet after a week, then the cacti are wet for a too long period and they may lose their roots. The top layer of the soil should dry up within a few days, but deeper down there should still be some moisture after a week.
Why not place the Mammillarias outside? I would expect that the Mexico City summer should be suitable for growing cacti outdoors. As long as they are in a well-draining soil, get lots of moving air, and warm weather, they can sustain quite some rain.

Wolter ten Hoeve, The Netherlands.
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Cactusero incipiente



Number of posts : 5
Age : 29
Location : Mexico
Registration date : 2011-01-11

PostSubject: Re: Shrinkage    Thu Jul 14, 2011 12:35 am

Hi Wolter, thank you for your reply.

I used to have my Mammillarias outside. However, summer rains killed many of them last year. It was just too much for them to handle: too much water. The outdoor soil is a well-draining soil; however, what happened last year was that summer rains were pretty sustained (somedays it ran for three days, the 24 hours of the day). So the well-draining soil didn't help cause if the rain was "permanent" and intense for many days, the soil never dried. The three Mammillarias I had outside began to rot and died. I don't remember this kind of rains ten years ago, they were not like that. We used to have rainy summer, but no so rainy as nowadays. It is so rainy that some days are a little cold (not too cold as in winter). So as strange as it can sound, I take my Mammillarias indoor in summer, expecting them to have more warmth and light. Indoor temperature is 21 ºC/70 ºF. I give my mammillarias lots of light. Don't know if shrinkage could be related to this. Do you think so?

I water them twice a month in spring and summer, once a month in autumn and winter. If winter is too cold, no water during this season. Do you think twice a month is too much for them being indoor and at this temperature? Should I water more? I don't know what is causing shrinkage, but M. plumosa has already died. Sad
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woltertenhoeve



Number of posts : 226
Registration date : 2009-10-01

PostSubject: Re: Shrinkage    Thu Jul 14, 2011 9:37 pm

Hi Jonathan,

Could it be that your plants are 'thinking' that the growing season is over? The lower temperatures and decreasing amount of sunshine may trigger them to go in 'winter rest'. In that case, the shrinkage is natural and watering the plants might kill them. So, perhaps it is wise to stop watering them until the rainy days are over and there is more sunshine so that you can put them outdoors again.
Watering the plants twice a month in the spring with hot and sunny weather is more or less right, I would predict. Perhaps even more often (once every 10 days) might be even better, but it all depends on how rapidly the soil dries out. Addition of some fertilizer should be done about once a month during the grwoing season.
If you can cover the cacti with a glass plate (or plastic), that would also help. Then you can leave them outside in the summer and you do not have to worry about them getting soaked for days in a row. And when the sun shines, the temperature under the cover will rise to 25 C or higher, that will be very beneficial.
I think that you will have to learn by experiment what the best conditions are for growing cacti in Mexico City. Perhaps people from the university can also give you some advice about which cacti are suitable. The UNAM does have cacti in its Jardin Botánico, so a visit to that Jardin might be fruitful.
It could be wise to experiment first with cacti that are not so sensitive (M .plumosa and M. herrerae are not the easiest to grow; M. carmenae and elongata are easier). Rather easy species are M. rhodantha, discolor, spinossisima (just a few examples), they all come from regions around Mexico City where they are adapted to fairly wet weather in the summer.
I hope this helps,

Wolter.
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Cactusero incipiente



Number of posts : 5
Age : 29
Location : Mexico
Registration date : 2011-01-11

PostSubject: Re: Shrinkage    Fri Jul 15, 2011 6:54 am

Thank you, Wolter. I'll put in practice your advices.

Probably they are just dormant, but never thought it that way. No more water then... time will tell. Fortunately, summer rains are about to come to an end, so I'll try to take Mammillarias outside again when it is appropriate for them, with the precautions you suggest.


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Saurny



Number of posts : 2
Registration date : 2016-08-21

PostSubject: Re: Shrinkage    Tue Oct 04, 2016 8:35 pm

Shrinkage can be from desiccation OR from too much light. Some species grow more spines, the spination becomes denser, and the height shrinks markedly, when sunburn or excessive grow lights threatens the epidermis. This happened to a M.haageana I have, which stretched out again most dramatically over about three months, when taken out of a south-facing window and kept away from grow lights trained on other plants. The green epidermis of the mammillae began to show again, as the spination thinned out.
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