Cacti and succulents vs the rains

The rainy season in the Philippines, as per the Philippine Atmospheric Geophysical and Astronomical Services Administration (PAGASA), formally began on June 8, at the effects of tropical cyclone Maliksi, known as Domeng in the Philippines.

The rainy season of course is the bane of many cactus and succulent hobbyists, and for good reasons. For many, this is the so-called 'season of rot'. But when the incessant weather came, I just left my succulents from where they are, out in the open. Admittedly, I forewent common sense and just allowed them to soak as much rainwater as they possibly can. Call it madness, but yes, I just left them there. And it rained everyday, often heavily and in sudden bursts accompanied by strong winds. Periods of respite are defined by overcast skies with some mists and drizzling. By June 12, I was becoming uneasy and was already considering sheltering the plants; if the experimentation fails, the consequences would be massive- cacti can burst open from too much stored moisture and the succulents, most of them stapeliads, can start rotting from their bases by the continuously moist media. But I decided against it, because I wanted to know my plants' limits; the search for knowledge drives men to take risks.

There are other plants not photographed for this entry, and those are the ones propped on benches. Some are protected from the rain. Even if I have taken a risk and sent some bit of mainstream preconceptions and knowledge to a vacation, I ain't that dumb to subject plants with limited tolerance to driving rain expected to last for more than a couple of days. Doubtless, this experimentation would have ended in woe for mesembryathemi, most caudiciforms and bulbous plants, and some plants from hyper-arid habitats. The very commonly available stapeliads Huernia macrocarpa and Orbea schweinfurthii both display aversion to excessive watering. But for the plants above, it sure is a punishing situation. Puddles have formed on places and many of the pots were in direct contact to the ground, making the bases of the pots and the media within it constantly wet. You may even notice that algae have begun to colonize these little pools of rainwater.

And yet, the plants marched on. Some of the cacti produced a burst of new spine growths in response to the sudden deluge of water from the skies. It is June 13 as I write this and still no signs of the plants relenting. We had a bit of brief sunshine this afternoon but rain is threatening again. If no change happens weather-wise I may need to shelter these plants. Or maybe not.

The new spines on this Melocactus started to appear a couple of weeks ago, but remained short. The typhoon-influenced rains induced the spines to grow quickly.

Orbea dummeri continues to bloom despite the rains. 

When the rains came, the leaves of Frerea indica expanded significantly. You can even see a little peduncle forming on the right side of the stem. For many cacti and succulents, flowering is triggered by the onset of the rainy period.

 What happened here?

Popular 'knowledge' states that succulents, including cacti, and rain do not go well together, and there is every reason to believe that. These plants after all have specialized stems designed to hold water and nutrients, but there of course is a limit to how much they can take. This segment of horticulture is replete with stories and photographs of plants imploding and rotting due to too much water. Just yesterday I saw photos of plants from local collectors that have met the same fate.

So what's with my plants and why do they just seem to sneer at the sudden aquatic vengeance from above? I can think of three reasons. The first has something to do with the medium itself. It is heavily mineralized- open and very fast-draining. But let's qualify 'fast-draining' first. So many who are into cacti and succulents, particularly the novices, apply this term to any soil that sheds water fast. Even coco peat drains quickly. But is it applicable for use for succulents? Well yes, but only for a limited amount of time, because it is an organic material and organics eventually decompose. Under my conditions, coco peat becomes mush in less than a year and the particles have already become so fine and impacted that drainage becomes practically impossible. You never get that issue with rocks. And those negative spaces in between the mineral substrate actually encourage aeration around the roots- the roots may be moist, but these are still able to breath. They never become waterlogged.

The second reason, I can ascribe to over-potting. I have seen and heard arguments that cacti roots have to be kept in check, or these plants will put up more energy producing more roots instead of channeling that same energy into the development of its stems. There are some counter-intuitive points contained in that argument but I will begin by acknowledging that cacti roots are best constricted. Observations from nature suggest that many cacti grow on cracks in rocks, and this causes the plants to produce an extensive root system that penetrates available crannies in search for a reliable source of nutrients and moisture. One of the basic tenets in horticulture is that a gardener's efforts should be focused in the health of the roots- a healthy root system is manifested by the health of the vegetative parts. But evidences point to root constriction in cacti, and possibly with many other non-cacti succulents too, as integral in a good and functioning root system. Many growers solved this quandary by placing pieces of rocks around the roots but using a large enough pot- you constrict the roots but you also provide room for further development. Using a small pot hinders root development. Period. If you want a nice-looking plant, let its roots develop. Another advantage of using large pots, and I have mentioned this not a few times already, is that such pots are good insulators against the vagaries of weather conditions. Small pots heat up faster than larger ones, and small pots soak up and retain water for longer periods than larger ones due to less surface area.

And here's a third, likely reason: I severely withheld watering to these plants for three months, from March to May. Watering is usually carried by mistings at night at very irregular intervals. Usually for Stapelia, I only water directly when the stems begin to soften. In all those three months, I only soaked and bottom-watered the plants only once, at the end of May. The fraileas looked dead and the gymnocalyciums appeared emaciated. When you look at cactus stems, you'll often see ribs that give them an accordion-like appearance, if you imagine the stem being laid in one plane. In periods of drought, these ribs contract then expand considerably when moisture is present in large enough quantities. Prior to the beginning of the rainy season, my plants were very lean. So when the rains came, there's plenty of room within their stems to absorb water into. The sudden development of spines probably also came as a direct result of the current levels of precipitation, as spines are now also known to store water too. I highly doubt if all these plants can take up to seven days of rain though, although I have plants here that I have been keeping for five years or more and still growing even when subjected to extremes year after year.

The spines on this young Ferocactus are developing more wickedly.

Some of the plants here have their bases colonized by algae and mosses, as well as other organisms that constitute the crust. This layer absorbs excess water and assists in thwarting off the likelihood of base rot and attacks from saprophytic fungi. If you have these on your plants, leave them be!

A plant's ability to withstand trying conditions can only be very rarely attributed to a single cause. Often it's multiple, yet interconnected. And when these factors come together, they often fit together beautifully, like pieces on a jigsaw puzzle.

I featured this plant on an earlier post, showing the extent of the stem's regression towards the substrate. The recent rains caused it to balloon back into the surface. 

Disclaimer

I certainly do not encourage anyone to try what I have done here, unless they are willing to take the risks and only for the purpose of learning something new. I also do not advise leaving their plants in the open, and a greenhouse is always a good investment. Likewise, producers may (again) be rubbed off the wrong way here, but this post is not geared towards them anyway. Most of my practices go against the grain of what the producers do. In the same vein, established collectors may be offended (again) by this post, but this entry is not meant to decry their practices nor their soil mixes. If you think you are already successful at what you are doing, then why try a different approach unless out of curiosity? One does not fix what is not broken. This post is meant to illustrate the possibilities and to dispel some common beliefs, albeit with some reservations and limitations, using arguments based on the biology of the plants tackled here.