How does living in the tropics alter cultivation?

[David48]

I am currently living in Brazil 4 degrees south of the equator. My home country is UK with its northern hemisphere seasons.

Here the days are pretty much the same 85-95F and daylight more or less the same each day. It is like the hottest of UK summer days. There is some seasonal variation in rainfall - some rain January to March then drought the remaining nine months.

Do cultivated cacti need a rest period to correspond to the northern hemisphere winter in order to flower or is it just a case of permanent summer?

Any other differences advice.

I started to put my cacti on shelves on a garden wall facing south but discovered that right now that is perfect but when the sun heads back to the Tropic of Cancer the plants will be in shade for about 6 months-one discovery is at the equator half the year the sun shines from the south half the year from the north (or proportional to location within the tropics).

[DaveW]

Most cacti have a rest period, even if not due to temperature but due to dry periods when they more or less shut down and wait for the rains again. Some of the higher altitude cacti like Rebutia's and Sulcorebutia's etc may grow well in permanently warm conditions but not flower as well without their cool winter rest. However you should do well with the sort of plants JP grows since as you will know we need heat to grow them in the UK, therefore probably he can advise you:-

http://www.cactiguide.com/forum/viewtop ... =2&t=36783" onclick="window.open(this.href);return false;

http://jp29.org/brculty.htm" onclick="window.open(this.href);return false;

Also see:-

http://www.bcss.org.uk/foruma/viewtopic.php?t=95524" onclick="window.open(this.href);return false;

http://www.brcactaceae.org/e_index.html" onclick="window.open(this.href);return false;

http://cactiguide.com/piclocation_displ ... number=693" onclick="window.open(this.href);return false;

Just keep clicking on "Next Article" at the top of the page to see following pages in this link:-

http://www.bioone.org/doi/abs/10.2985/015.081.0302" onclick="window.open(this.href);return false;

The problem is we all try and grow the plants that don't suit our climate rather than those that do, therefore you may have to modify your choice of cacti to suit your conditions or struggle growing some that like a cooler winter rest to flower well. However tropical cacti should be no problem for you now.

[graffiti]

Sounds like a great place for growing Hylocereus and getting fruit from them.

[esp_imaging]

I'd view this as a great opprotunity to experiment with tropical cacti that aren't grown much in the UK. Maybe Discocactus, Melocatus, Uebelmannia etc are easy where you are?

If you are just south of the equator, your south-facing wall should be (slightly) shaded at the moment, and get increasing amounts of sunlight as the sun moves more into the northern hemisphere for the northern hemisphere summer.

However, close to the equator, the sun will more-or-less arc from east to west during the day, and be more-or less overhead at midday all through the year. So the shading aspects of a north vs south facing wall will be far less than in the uk.
The effects of the top shelf shading lower shelves may be far larger though!

[DaveW]

One disadvantage you have, if you can call it that, is it is easier to warm a greenhouse as we do in the UK than refrigerate it. Whilst cooling fans may help in winter they would be unlikely to get the temperature down to just above freezing for those plants that like a cool winter rest to perform best. For some plants like Pterocactus and Austrocactus from Patagonia even UK greenhouse summer temperatures may be a little too warm for them and they do better in an unheated cold frame in winter just to keep the rain off and out in the garden (yard) in summer. I have even seen pictures of them growing near the beach in Patagonia with icebergs floating by on the sea. We all have to make some sacrifices to our climate if we grow cacti wherever we live if we cannot provide the right conditions. The good thing is cacti exist from fairly cold, but usually fairly dry climates, to tropical ones so there are always some that suit your conditions.

[David48]

Thank you for your replies and food for thought. I know I would love some air conditioning here but I had not thought the cacti would require cooling too.

Mostly I have bought plants, good size, I think good price about 2 GBP from someone at a Saturday market. Most of the offered plants are Mammillarias Gymnocalcium not the more exotic specimens recommended above.

Echinopsis oxygona (I believe right ID) thrives and flowers also Mammillaria polythele (ID from earlier post on this thread). I have to wait and find out about the other 20+ plants. The spineles cereus which goes by peruvianus and other names thrives outside. I hear the spineless cereus is used as animal feed which makes me wonder if the debate over name could possibly caused by an historic case of hybridisation for creating a spineless animal food-not sure if anyone confirms that the species is natual in the wild.

The sun is overhead nearer to the equinox then I may have to move them off the wall, or they will have no direct sun at all. Right now they are facing the sun most of the day.

Last night I the potted plants them-very heavy rains started here-after 9 months drought.

Thank you again. I will chase up the links.

[David48]

I am in the NE of Brazil, the state of Rio Grande do Norte. The local habitat is named "caatinga" a dry scrubland.

Brazil in itself is about as big as a continent so very different region to region.

[DaveW]

Most cacti will grow and flower normally in many climates. However some do like a cool winter rest to flower well, particularly if they come from altitude. For instance within even a small area in habitat you can have cacti that inhabit hot lower altitude valleys that need warmth all year round, whereas genera growing only a mile or so away on top of the high hills surrounding the valleys can experience cold in winter and not flower so well unless they do get a cool winter rest.

I remember a speaker who had visited cactus collections in one part of India telling us in that part they could not flower Sulcorebutia very well because the plants did not get a cool winter rest. However they grew the more tropical cacti far better than we could. As you say, there are often many different microclimates within a country and some plants will grow better in one than another, whereas other cacti are pretty tolerant of most climates and flower normally. It's a case of seeing what grows best for you.

You sure your spineless cereus is not a Trichocereus rather than a Cereus? Easy to tell a Cereus from a Trichocereus in flower as a Cereus has a naked flower tube where Trichocereus has a hairy bristly flower tube.

[piyeron]

Hello! I live in the Philippines which is also a tropical country, and mostly it is as Dave has previously mentioned-- cacti that need strict winter rest to flower may grow fine, but won't flower much if at all. We have a very wet monsoon season and during this time it's very easy to kill most succulents due to very wet and still very warm conditions. I've not much experience with those that come from cold/really cold regions, but judging from the likes of Sempervivums (which are oddly common here since they are cultivated en masse in the cooler highlands), lowland tropical culture of alpine or cold region varieties is very challenging. Perhaps not totally impossible, just truly difficult. Our problem is excess heat, as opposed to

Things like Echinocactus grusonii somehow aren't as compact or thick spined than those grown in areas that can get cool to cold for at least part of the year, and propagating smaller cuttings can be quite toilsome as the heat can make them sluggish to establish.

It's only recently that it's easier to acquire the rarer/more desirable/exotic species here too, and I'm trying to get my hands on tropicals like Discocactus, Melocactus, Uebelmannia, etc. and see how easy or difficult they will be here

[Aiko]

You should try Adenium. They should grow like weed where you are!
Maybe Pachypodium too? And probably most of the caudiciforms from Africa should like your climate, like Petopentia and Cyphostemma (which can take a lot of water).

And how about Pseudolisthos, Whitesloanea, and many other asclepiads?
I am also thinking about species like Welwitschia (which should also get very frequent waterings and warmth) should do well where you are.

Seeds of most of these species are not that hard to obtain.

[DaveW]

As Piieron says Aiko it can often be difficult to acquire such ready made exotics in their country. However they should not overlook raising them from seed as seed usually travels easily around the world and so they are not limited to seedsmen in their own countries. Also they probably have ideal climates for seed raising such plants and seedlings will probably grow faster than we can grow them in cooler countries. We should not always expect to rely on nurserymen raising our plants for us, plus there will always be a greater range available as seed than plants because nurserymen tend to raise what is the current fad or easily grown in their conditions, so more profitable. Many seedsmen now use PayPal, so currency exchange and payment is not the problem it used to be.

Try the online nursery websites on Cactus Mall for seeds you are after:-

http://www.cactus-mall.com/seeds.html" onclick="window.open(this.href);return false;

Edit:- just searched the Web and came up with these that may interest you Pieron and David:-

http://www.philstar.com/modern-living/1 ... ti-tropics" onclick="window.open(this.href);return false;

http://www.kadasgarden.com/Cwetcacti.html" onclick="window.open(this.href);return false;

http://www.growsonyou.com/hywel/blog/22 ... rest-cacti" onclick="window.open(this.href);return false;

http://www.cactus-mall.com/csp/" onclick="window.open(this.href);return false;

[David48]

Thank you for this mine of information.

[David48]

It is now the wet season here - by "wet" it is really wet when it rains.

I think I have refined my problem through this discussion-to get flowering I should introduce a rest period despite the sun and heat. January-March are usually wet. The plants are in the garden but put under cover when the heavy downpours arrive.

So my new question becomes when should I try to rest the cacti? Would it be the same for all species?

[7george]

It depends. Some will rest when it's dry, other when cooler or sun is less, or all of it. Some will keep growing. Which species you have there?

[David48]

I have around 20 plants only a few specifically identified.

Genera are mammillaria, echinopsis astrophytum gymnocalcium and a few plants I am not sure of the species.