@Tomas: Interesting - so cuttings retain their maturity, then?  Nice to know; whenever I have to prune it back I can make a bunch of babies that don't take long to fruit.    Heh, planting outside isn't an option for me.  That would otherwise be known as "purposely killing my passionfruit"    A cold snap can drop temperatures below freezing in even september here.  And you know how some tropicals can stop growing if temps go below 10C or even start to die back (for example, I know that coffee does that)?  Half our nights even in July get that cold!  And our average July day gets up to only 15-16C! (~60F, for those of you in the US).  Our winters aren't super-cold by American standards, but we basically have no summer.

@Fyliu: Indeed, I posted the top picture for comparison.  I've been getting shoots like the top one for a long time; they grow into vines.  But the bottom type I don't think I've seen before.  I did some google image searching of passionfruit buds, and I think it is a flower.  Yeay! 

@stressbaby: The concept of root pruning has always scared me, but then again, I've heard it can be good for a plant.  So I'll probably give it a try in a few months when it inevitably fills up the 15 gallon. 

@fruitlovers: I already moved it into a 15 gallon, heh; I'll just deal with having a very large passionfruit vine and probably end up giving a bunch of fruit away.  Or hmm, wonder if I could sell it here.  Icelandic-grown passionfruit on a commercial market, I bet that'd be a first.  Does passionfruit fruit in flushes or continuously?  No worries about it growing into the ground; the ground is a solid floor and there's an undirskál (in English, what do you call that thing you put under a pot?) between it.   

Oh, hey, speak of the devil - is this a new type of side shoot I'm seeing -- perhaps a developing flower bud???  Or am I just being too optimistic?

Old shoot type, grows into a branch if the plant feels like it wants one there:


New type - blossom?:

So as you know, I do my growing of tropicals indoors under lights.  This weekend I had a nice transplant-fest, wherein I buy a couple large pots from the IKEA in Garđarbć and then shift everything up a notch - plant A goes into a 15 gallon, freeing up a 7; plant B goes into the 7, freeing up a 3 gallon, and on and on down the line to transplanting-up seedlings.  One of my large transplant-ees this time was my passionfruit, which went into a 15 gallon.  As I suspected, it had been starting to get rootbound, so I felt I just had to move it up a pot size.

However, 15 gallons for a passionfruit, I can't imagine going any bigger than that.  I've seen pictures of people fruiting them in 5 gallons.  Given it's history, I'm afraid it's just going to bind up again.  Do you think it's okay just to let that happen?  It's never flowered, and I'd hate to have to have to go even bigger just to get it to flower - I need room for all my other plants, quite a number of which are ultimately going to need 25 gallons or more!    I plan to try to induce flowering a few weeks from now with a low-N, high K/P fert. mix I made, once it's burned through most of it's current mix, but if that doesn't work...

Also, as a side question, while English is my native language, I'm starting to find myself having deficiencies remembering English words sometimes if I don't use them often. What do you call the thing that you put underneath a plant pot to protect the floor?  It's undirskál in Icelandic but I just can't remember the English word for it.

Some of them best tasting Solanums are truly tropical

Even garden tomatoes are really tropicals - just fast-growing annual ones  .  Heat lovers that die back at the first sign of cold.

Has anyone here tried cocona?  I've wanted to grow it ever since I saw it on an episode of Survivorman, and finally picked up some seeds (which I'm hoping will sprout within the next few months, if I'm super-lucky)... but I've never tried it before.  It's another of those semi-obscure solanums, all of which seem to have a flavor that people describe as "A cross between X and a tomato"  .
een

Well, if it was poisonous, and its poisons were characteristic of the genus, they'd be anticholinergic chemicals - that is, they act like nerve agents, blocking a single receptor in the nervous system.  The upside of such agents is that if you survive, there's generally no lasting effects; they're not bioaccumulative or cause organ failure or anything like that.  Given that you didn't even get *symptoms*, I'd think the plant would be pretty safe.  Heck, I'd be more worried about eating annonas because of the possible Parkinsons' risk, since that's a long-term thing.  Of course, I eat them anyway, just not too much   

If I had a green house I would try to grow Passiflora lingularis, and that large tropical one related to quadrangularis. P. alata is popular in Brazil and the locals there would chase the bees away so they don't steal the pollen. Manual cross pollonation with a different genotype is necessary for fruit set. Both are better than the regular edulis people grow in SoCal.

Lingularis is called Grenada china(Chinese pomegranate) in Mexico.

Any clue whether they can cross pollinate with edulis?  Always looking for ideas to add to my wishlist 

I think that when the passionfruit starts to burn through its current time-release fertilizer, I'll switch it to a low-N  and see if that helps encourage it to bloom.

Re, the cherimoya: Is chill needed just for fruit, or for general growth as well?  Because mine's not ready to try to push fruit on yet.    The only one of my plants I'd feel comfortable trying for force fruits on is the passionfruit, but I don't know how to do that and I'm not in a super rush at this point.  Well, my largest coffee would probably be fine with fruiting too, but I'd rather he grow another dozen centimeters or two.  Same with my orange.

Stressbaby: The one and the same!  I live in Iceland now though; Iowa wasn't far enough north**    And I live in a duplex that has a common two-story geothermally-heated greenhouse (although I do most of my growing in my section of the house itself).

Thanks for the tips, both of you.  And yeah, I've found that my coffee prefers it wet, but it doesn't die readily if it gets dry like some plants.  If the soil gets bone dry then they do the whole tomato-plant thing of putting on a big show, "I'm A Poor Thirsty Plant, I'm DYYYYYING!!!!", then you give them water and 6 hours later it's like nothing ever happened.    But I guess that makes sense for the sort of climate they're native to where there are both wet and dry seasons.  By contrast, when my jabo got dry when a plantsitter neglected it, I had to basically put it on life support for a month; it's a miracle it and its three tiny half-dead leaves survived.


** Let's see... SoCal to Texas, Texas to Indiana, Indiana to Iowa, Iowa to Iceland... at this rate I think in 10 years I'll growing tropicals in Svalbard and will probably die as the greenhouse caretaker for the first human colony on Europa, lol 

Hehe, like I said before, just have something innocent that you can pass it off as.  Back when I wasn't sure I'd be able to get my permits at all, I was coming up with all kinds of crazy ways to get the plants in, like turning them into wreaths or parrot toys or furniture etc while still alive... even did tests to see how extreme of conditions they could survive     Heck, I probably could have passed my passionfruit off as a wreath even when it was coming in as legit, as I had to reel it in a whole bunch and bind it up, and the root bundle wasn't visible through all the leaf mass.

Oooh, awesome to know that you can fruit them in such small pots and such a small size    A couple fruits every now and then is all I need from dragonfruit.  I like the fruit because they're so beautiful; the taste is kind of bland, IMHO.  As for varieties, living in Iceland, I'm kind of stuck with the variety I have at least for now, heh    It's not that you can't get unusual plants here which are not adapted for the climate (I picked up my olive tree here for example).  It's just that the safe default assumption here for tropical non-houseplants is always "not available until proven otherwise".  I forget which variety I'm growing, it's been so long since I ordered it, but I did compare a couple varieties before selecting this one.

As for the light, well, you have to compare it to the sun.  Most of the amazon basin gets 3-5 kWh/m˛/day.  So let's say 4.  That's an average of 167W.  The peak solar intensity on a perpendicular plate on the surface is 1000W, but there's night, there's clouds, there's angles, etc. 

Now we look at an artificial lighting setup.  First efficiency comes into the picture - not luminous efficiency, but quantum efficiency (luminous efficiency takes into account how the human eye sees light, which is irrelevant for plants; the human eye sees green best while green is worst for photosynthesis).  You'll get up to 30% on a good tube.  LEDs can approach 40% external quantum efficiency.  Because of bulb age and not having optimal bulbs to begin with, let's say 25% and 33% respectively.  Then there's light loss.  On Earth, the sun is always striking *something*, and if you have a plot of plants, the light that escapes hitting your plants is offset by light that escapes hitting other plants and hits yours instead.  You set up grow lights indoors, part of the light will escape and hit... well, something you don't care about.  Let's say 60% is useful.  So right there are some pretty massive losses.  Now there's the spectrum to take into account.  Actually, this is an advantage for indoor growers, because a third of the sun's energy is in infrared, which is worthless, and the rest pretty evenly spread, while photosynthesis absorption bands aren't.  Fluroescents are sort of a mixed bag in terms of what visible spectrum they provide, but at least there's not much IR** -- let's say credit them with 120% of the sun in terms of spectrum efficiency.  LEDs, with blue and red, esp red, are spot on for photosynthesis; credit them with 200% spectral efficiency.  Note that we're not considering hormonal effects of a different spectrum than the sun; for example, while my dragonfruit loves all that LED energy, I know from experience that if I were to try to grow, say, lettuce under it, the lettuce would be horribly lanky and basically a disaster.  But here we're just talking about energy.

So, to match the Amazonian sun with fluorescents, you need 927W/m˛.  With LEDs, it's 421W/m˛.  Note that that's per square meter.  Growing even a couple square meters indoors like I do, and well... matching the sun takes a lot of light!  During the winter I'll have to replace pretty much the entire sun; there's several hours of "dim" outside but the sun won't rise over the houses to my south until late February or so.  During the summer at least I have those nice picture windows to help out. 

I really think that the number one limitation of most people growing plants indoors is not grasping how much energy plants really get from the sun and how little most indoor lighting provides.  Our eyes see light logarithmically, not linearly.  It may not look that much brighter outside, but it really is.  If we saw light linearly, outdoors would be blinding and indoors would be like a cave.  And it makes sense that it takes so much energy to produce food when you look at internal plant losses; food crops which are fully healthy and getting enough light (and everything else) range from a tiny fraction of a percent to 1% of their energy going into the final edible portion (fruits and vegetables), to a couple percent (grains), to as much as 10% in extreme cases like sugarcane.  So a 1% efficient plant in the Amazonian sun is actually only getting around "productive" 1 1/2 kilowatt hours of energy per square meter month!  That's 1200 food calories per square meter per month.  And if you "underfeed" the plant in terms of light, it's going to be needing all of the energy it gets just to try to stay alive.


** To be fair, there actually *is* a lot of IR, but it's far IR, heat radiating from the glass and ballast due to the efficiency losses - and since that's already counted under the efficiency losses, there's no need to count it twice.

Ah, fruitlovers, good to hear from someone who is personally aware of the pain that is shipping plants internationally   

Jason: Heh, it's not hard to bypass customs regulations or work through loopholes.  Heck, here in Iceland all they ever seem to care about is alcohol, people bringing it in trying to avoid taxes.  It almost made me mad, after all the pain and expense  I went through to get my permits (including becoming certified as a grower under USDA supervision), that I showed up at the airport in Keflavík with my nice shiny certified forms from all respective parties, and all the guy was concerned about was whether I was bringing wine, and if so, how much.  Didn't even ask to open my suitcases to make sure that the plants I was bringing were on the list.  I could have had my bags packed with 100 different endangered species infested with every plant disease known to man being used as travel snacks for a swarm of Japanese beetles, and nobody would have known the difference.  :Ţ 

behlgarden, Filipe: It can be done; I did it.  The only plants I list were two fairly mundane ones (lemon verbena and stevia) and a plumeria cutting which I think was already a goner (the people I got it from didn't preserve it right and it had a rot spot on it already).  And I brought them to Iceland, in February at that!  But there's no question that it's really hard on the plants.  I don't plan to do it again.  Maybe planting an occasional leftover, mind you, but...    I've lost a lot more plants to plantsitters over the years than in transporting plants.  This is one place where you outdoor growers are so lucky, that your watering requirements aren't so strict.  I still miss my silver-hair tea, my pair of kiwifruits, etc... almost lost my jabo, too.  It was within an inch of its life with only three tiny half-browned leaves as its only source of energy for something like a month before it managed to get enough energy together to start producing more.  And it amazes me, no matter who I bring in to water (except my last plantsitter, who is awesome), the post-mortem conversation always goes like... "Wait, you really didn't notice anything was wrong?  Really?  You didn't notice that every plant in the room had drooping leaves, some turning brown, some falling off, some plants now bare?  You REALLY didn't notice that?"

I'll note that at least for export to Iceland, I had to get permitting for budwood cuts as well.  But at least they're easier to transport. 

Note that there's two sides to approval on anything, but especially with any living plants/plant parts: export and import.  With export, they're mainly concerned about CITES.  With import, they're concerned about CITES also, but especially disease, pests, etc.  And don't expect the approval process to run so smoothly.  Mine was a tidal wave of ups and downs.

So I've got several dragonfruit plants (was "one dragonfruit plant", but, well, anyone who's grown dragonfruit knows how easy it is to root anything that breaks off...).  The largest, "mother plant" is now big enough that she's starting to sprawl all over the place, and indoors, where space is limited, obviously I need a better solution.  What do you all recommend to support them?  They're kind of awkward plants so I'm not sure how I'd train them to a trellis.  Maybe I could just simply tie them to a big stick?  I was considering perhaps hanging a large pot from the ceiling and letting it drape, hopefully eventually acting as a backdrop to capture escaping light from my grow area - do you think that'd be advisable?