Rain has arrived with a bang!

[abhikjha]

Hi Guys, need urgent help!

I am in Mumbai where the rainy season has arrived and what an arrival it has been. It will be full wet 2 months. So hot and humid with almost daily rains. To give you some perspective, in just 10 days of June, we got 470 mm of rain while the monthly average is 500 mm. Some news suggested that it has broken last 120 yrs record. Temperature is in the range of 32 to 26 C.

As soon as it started raining, I brought all my cactus indoors. When it pours heavily, to cut down the humidity levels, I switch on AC, otherwise fan is 24 hrs on.

All my plants are in full mineral medium. Mostly pumice(90-100% pumice). I have a decent collection of Astros, Obregonia, Ariocarpus, Melocactus and Discocactus.

Good thing is I watered all of them around 10 days ago so all are plump right now but I guess they will soon need water. And that's where my questions lie.

1. Do you think I keep on watering them every 2 weeks or cut down watering till the time we see sun and clear sky? The dilemma is if I don't water, they will be very thirsty especially if AC is on. And if I do water, then chances of rot will loom around.

2. If I water them, can I use sip method instead of soak till water comes out of drainage holes?

3. I am planning to use systematic fungicide watering whenever I water them to cut down the chances of rot. And once in this rainy season, hydrogen peroxide watering to clear any growing pathogens and oxygenate the roots.

Please help me, especially those guys who are growing in tropical weather..

Cheers!
AJ

[mmcavall]

Here is my experience, as a "tropical" grower:
My summer is hot and wet (same temps as yours) and I certainly don't let my plants take any rain. They are outdoors, but protected by a plastic roof (my greenhouse don't have walls, only a roof).
But I do water them a lot in this season (summer), once a week (depending on the genera and size of the plant) always soaking the pots until water drains from below. I water them despite the wet weather because this is the growing season.
(I do avoid watering when it's raining , or in a rainy week, but anyway they will receive water very frequently).
As temperatures decay, I diminish waterings and in winter I don't water them or just water very slightly (again, depending on the genera and size). My winter is dry and relatively hot.
That's what I do here, not sure it helped. I believe that you can be confident to water your plants when its hot, provided you let the soil dry between waterings. But, consider the following: when the weather is wet and cloudy, the atmospheric demand is minimal (I mean, the plants don't loose too much water and really don't need to be watered) so you can always wait for sunniest weeks to water them again.

Concerning your collection, I particularly don't like the idea of bringing them indoors and using AC. That sounds dangerous. Not sure they will like it. Is really impossible for you to let them outside with a plastic covering?
Possibly indoors you are providing much less sun then outside. Now they are indoors, be careful with waterings because temperature is lower (outside temperature does not matter anymore) and sunlight too. You are creating an artificial winter for them so I'm not sure you should water them.

[abhikjha]

Hi @mmcavall, thanks so much for stopping by and response. I was really hoping that you could see this and respond as you are one of the successful growers in a tropical area on this forum .

It is so assuring to see your response on watering regime in a rainy season. Actually for my plants, this is the first rainy season, so wasn't really sure what preparations to do. However, a plastic screen which can let the sunlight pass but stop the rain is definitely on cards. I will follow your advice on watering them in growing season. I actually follow once in two weeks for most of the plants when rains started and am definitely not watering in a rainy week. Today the week long rains ended and sun appeared, so I watered all of them.

Yeah, bringing them in AC was a kind of overkill, but fortunately I switched on AC once or twice for a couple of hours when it was extremely heavily raining and room was quite moist. I will take care not to do this again.

My winter is also hot and dry. Problem is in summer, my South facing house balcony receive lesser sunlight (adjacent building partially blocks the sunlight), so this act as shade kind of thing but in winters, I get ample sunlight. So not watering them in winters is I guess not an option. I know they won't flower much, I am not expecting it either as this is the biggest drawback of growing desert cactus in a tropical area. If your winter is also hot and dry, how do you manage by not watering them often?

Cheers
AJ

[mmcavall]

Hi AJ, glad to help you. Most of what we tropicals read in the forum is not applicable for us, we have to adapt.

Concerning winter waterings, it depends on what is "hot". My winter is very sunny, with very few cloudy days. Temperatures are on average 23C Celsius during the day,
and nights are about 15, rarely below 10. European growers would say this is hot, something like their spring.
Well I can say that it is perfectly possible to not water the plants at all with this climate. From May 15th May to August 15th I simply don't water my Mammillarias, Sulcorebutias and Discocactus for example. I water other genera such as Frailea and Gymnocalycium. You will have to adjust this, try, and learn from your errors. There is no recipe.

(Once I did an experiment and let some plants 60 days without water in the high summer, and none of them died. I'll search for the thread and post here).

Additionally, I would say that roughly speaking the flowerings increased here since I started to give them a dry winter. Apparently most of genera need that to bloom.

I'm worried with your waterings in summer. Please be careful since they are indoors now.

[mmcavall]

If there is not too much differences in temperatures from summer and winter, and if winter is really hot and your plants take more sun than in summer, you could consider "swapping" the seasons and water your plants in winter (it would be the growing season) and don't water at all in summer (you have to be sure to cover them with plastic). It may work. All depends really on your climate. It would not work for me because summer is much hotter than winter, nights are hot too.

[mmcavall]

viewtopic.php?f=31&t=38213&hilit=Die+first

[abhikjha]

If there is not too much differences in temperatures from summer and winter, and if winter is really hot and your plants take more sun than in summer, you could consider "swapping" the seasons and water your plants in winter (it would be the growing season) and don't water at all in summer (you have to be sure to cover them with plastic). It may work. All depends really on your climate. It would not work for me because summer is much hotter than winter, nights are hot too.

This is interesting and thought provoking as well. I gave a serious thought on this. In Mumbai, we have rainy season starting from early to mid June and it goes till end of August. In this period, either it's raining or gloomy in most of the days. Humidity is super high but relatively cooler weather due to rains. We hardly get sunlight in this season, even if it's not raining, clouds make sure not to let sun out most often. Fortunately or unfortunately, this is the exact period in which my house balcony doesn't get sun. From September onwards, sunlight will start hitting the balcony and will reach to its peak in Jan and gradually starts declining again. This is a dry period as well.

So I have been thinking to get all my plants out in open between Sep and May (summer for them), water them frequently. Then between June to August, keep them inside, very little or no water (sort of winter rest for them).

I don't know whether it will work or not! Any views on this?

[mmcavall]

Maybe you could try with some individuals from each genera you have, until you fell confident to do that.