When I ended Part I, I was questioning whether the long and gruesome history of the partnership between humans and Dieffenbachia spp. could be moved in a different direction, maybe, and whether the transition that's already happened, from instrument of torture to decorative houseplant, is a step in the right direction. Which of course it is, and I apologize for leaving you in suspense about that, and for asking dumb rhetorical questions.
The genus is certainly undergoing some cosmetic changes. Lots and lots of varieties out there now, some of them sports, some hybrids, probably a couple sports of hybrids and hybridized sports. In nature, there are a number of Dieffenbachia species (consensus seems to be somewhere in the 20-30 species range), though taxonomy is a little confused because it appears that there have been some name changes, and I couldn't figure out for sure which names were still current and which were outdated. Given the amount of hybridization that's been going on in the plant trade, this is probably not terribly useful information anyway, but in case you're curious, the main names I ran across were D. seguine, D. amoena, D. maculata, and D. picta, in roughly that order, with occasional references to D. bowmanii and D. candida. Depending on the source, maculata might be picta, and amoena might be seguine. Cultivar names are only slightly more reliable, though the more famous ones, like 'Camille' or 'Tropic Snow,' are pretty easy to pick out of a crowd, and aren't likely to get themselves renamed.
I have no idea how one goes about hybridizing Dieffenbachia; what little information I have on it seems complicated, if not necessarily difficult. Most if not all varieties are bisexual, and have both male and female flowers. Flowering plants generally want to avoid self-fertilization, because there's no point in wasting all that time and energy to build flowers and pollen and so forth if you're just going to fertilize your DNA with more of your DNA: you could just reproduce asexually instead and skip the time- and energy-expensive flower-building. (Tradescantia pallida has more or less given up on sex, for example: it still makes flowers, but they don't do anything. Another approach is illustrated by Rhapis excelsa, which ensures cross-pollination by making all plants either one or the other, male or female, so any pollination that happens is going to have to be with somebody else.) Dieffenbachia's solution to the problem is to produce both flowers, but separate them in both time and space: male flowers at the top of the spadix, female flowers at the bottom, and the two mature at different times, so the female end of the spadix isn't receiving when the male end is shipping, so to speak.
It's a bit unusual for Dieffenbachia to flower in the home, but we see them flower on a pretty regular basis in the greenhouse at work. The 'Star Bright' plants are going right now; 'Tiki' flowered last February, and it seems like I saw some blooms last fall too, though I'm not positive. I have yet to see a Dieffenbachia flower that's actually been fertilized, though I've seen this with Aglaonema and Anthurium andraeanum and it's not as exciting as you might think. Neither of those produced any actual seeds, just the berries. Whether this means that the berries weren't mature enough, not really fertilized in the first place, or what, I don't know, but the point is that cross-breeding Dieffenbachia in the comfort of your own home is not likely to work out without some additional equipment and training. (Plant Daddy? Call me.)
Dieffenbachia species are invasive here and there, mostly in tropical Pacific islands (the Cook Islands, Micronesia, Hawaii – of course – Fiji, Tahiti, Palau, Samoa, and so on). Amazingly, they are not listed as invasive in Florida, I suppose because even Florida occasionally gets a little chilly, and dieffs aren't great with cold. Even so, Floridians shouldn't get complacent. It's invaded before; it could do it again. Plus they're native to that general area in the first place: the Caribbean, Central America, and the northernmost bits of South America.
But on to the care information. When I was in high school, I liked Dieffenbachias, but I was never good at keeping them going for very long. Or at least that's how I remember it. My main issue, I think, was that I was overwatering, which is a big temptation for me when it comes to big-leaf plants like this. But even taking that into consideration, they seem to like certain people much better than others, and I'm not sure what accounts for the difference. If you find them easy, then they're very easy; if you find them difficult, they're going to be very frustrating. Also one can change from one group to another, over time, for reasons which are mysterious. So these are maybe not the best beginner plants. However:
Water: Dieffenbachia need to dry out substantially (though not totally) between thorough waterings, and also need a potting mix that drains well and quickly: peat moss is not your friend.2 If lower leaves go bright yellow and then drop, the most likely problem is that they're too wet. Never let a Dieffenbachia (or anything else, for that matter) sit in drainage water or plant one in a pot without drainage holes. I water my larger plants when they're at the point where I can stick a finger into the soil as far as it will go without hitting anything damp; for small plants I generally go by weight, and water when they've gotten noticeably lighter.
Light: A lot of sites and books will tell you that Dieffenbachia are good low-light plants. This is really, really wrong, and I'm kind of baffled that it keeps getting said. Left in a dark corner, a Dieffenbachia will drop leaves, grow tiny new leaves with less and less variegation on them, and otherwise look kind of like Laura Bush after January 21, 2009: sort of deflated and quietly miserable.3 Too much light isn't a good idea either: Dieffs can and will sunburn, sometimes badly, if they're in too much light. Varieties with large patches of white (e.g. 'Camille') seem especially prone to this, but they'll all burn if there's enough heat and light at once. Sunburn generally looks like a rounded light gray or tan patch on the leaf. The appropriate amount of light for Dieffenbachia is filtered sun or bright indirect light. My own plants are either under fluorescent shop lights or in a north-facing window, and they seem more or less content with that. Having said all that, certain varieties are claimed to be better with lower light than most, specifically 'Star Bright' and 'Snow Flake.'
Humidity: An ailing plant may well benefit from a stay in a spot with increased humidity, but I haven't found personally that it matters all that much. My 'Tropic Rain' has been doing fine right under a central air and heat vent for about two years now.
Temperature: Dieffenbachias do not react well to temperature extremes in either direction: cold will kill it outright (though the growers' guide says some cultivars can go to 45ºF / 7ºC without dying, I wouldn't personally risk anything below 60ºF / 16ºC), and heat will stress it and worsen spider mite problems, if any. Dieffenbachias are happiest in normal room temperatures, say between 65 and 80ºF (18-27ºC), even if they may put up with temperatures a little beyond that range.
Pests: In my experience, and also according to most of the books and on-line sites I've seen, spider mites are the main pest issue for Dieffenbachia. They can be difficult to detect, since some varieties have a sort of stippled appearance even when they're pest-free. We have had trouble with mites on the plants at work occasionally, though they don't seem to be that persistent, and it's usually only an issue when the plants are otherwise stressed, e.g. if we've got them in a really hot or bright spot. The bigger issue for me in the greenhouse is the bacterium Erwinia, which causes a particularly unpleasant variety of rot. Tissues liquefy and smell vile,4 and there's not much you can really do to clean the plant up: it's easy to transfer the bacteria from one plant to another (by hand, by infected tools, by splashing of water), so one just has to kind of cut off the infected parts, wash the plant in the sink, wash one's hands in the sink, and hope for the best. Dieffenbachias seem to be exceptionally susceptible. That said, it's not a common problem in the home: I suspect the bacterium needs humid conditions to really get going. So long as you're not buying plants that smell bad or have watery-looking spots on petioles and leaves, you shouldn't have to worry about Erwinia that much.
Grooming: It's normal for a plant to drop the occasional lower leaf as it grows, and the big leaves do accumulate some dust, but otherwise there's nothing extreme here. Given enough time, a happy Dieffenbachia will eventually grow a very long trunk with a little tuft of leaves; when this reaches the point of being unsightly,5 you may want to start the plant over; see next section.
Propagation: It won't work 100% of the time, but often, shortening an overgrown cane is as simple as cutting off the top and sticking it in a pot of soil. I prefer to start mine in water instead, because this seems somehow more hygienic: when I stick stuff directly into soil, I often lose it to rot (not just dieffs; lots of things), and when I root things in water, that tends to work out okay, even if it also takes forever, and the water roots that grow initially have to be re-organized into soil roots later. Your results may vary. Air-layering is safer, but time-consuming, and I'm not convinced that it's better. One can also divide plants; newly-purchased plants usually come from the growers as clumps of stems of varying sizes; these can be separated and potted up separately, if that's what you're into. Dieffenbachia will also sprout new stems from cane sections: cut a long stem into pieces about four inches long, half-bury them in potting soil, keep the soil moist, and you will often (not always) eventually get new shoots coming up from the cane's old nodes. This isn't the way professional growers usually propagate plants (the professionals tend to divide instead6), and for a professional-looking plant, you'll probably want to cut the sprouts off once they reach good size, and re-root them like tip cuttings (so the horizontal canes aren't showing), but it'll work. The overall point here is, Dieffenbachia is an easy plant to propagate, by a number of methods. Do be mindful of the sap, as you hack your plant to bits, though.
Feeding: More or less average for an indoor plant. They do grow year round, with only a slight slow-down in winter, so one could probably feed year-round as well. I have no consistent feeding schedule for my plants, and it doesn't appear to make a difference.
As regards specific varieties of Dieffenbachia, I find that the larger ones ('Tropic Snow,' 'Tropic Rain,' 'Triumph,' 'Alix') are much more easygoing than the smaller ones ('Compacta,' 'Camille' / 'Camilla,' 'Carina'). 'Camille' and I, in particular, have a history of discord and strife, to the point where I've given up on her. My second-favorite variety is this one,
which I have had for about three years, and which has been remarkably good about holding on to its leaves and maintaining reasonably large growth. The only issues we've ever had have been about light: last summer, it started to get scorched leaves when it was too close to a west window. I moved it elsewhere, and then it was fine. I don't remember how big it was when I got it, but it seems to have a fairly compact habit, considering how huge it is, and it doesn't grow very fast, so with any luck I'll have room for it for a few more years. After that, I'm not sure what happens. One of us moves out, I suppose.
My actual favorite, as I've mentioned before, is 'Sterling,' which is not a particularly flashy plant, but which somehow really does it for me. 'Sterling' is one of Plant Daddy's babies. There are at least two other named varieties which are similar: 'Hilo' and 'Green Magic.' I suspect that 'Green Magic' is just a renaming; the one picture I found looked just like 'Sterling' to me. 'Hilo,' on the other hand, appears to have longer, narrower leaves (more like 'Star Bright'), from what I've seen.
Another group of Dieffenbachia cultivars are the "grays." 'Tiki' appears to be a popular one at the moment, which seems a little odd to me: I don't hate it, but I've seen a lot of Aglaonemas that covered similar ground and did it better; I'm not sure it was really necessary. I think the other grays ('Snow Flake,' 'Panther,' 'Star White,' etc.) probably all share ancestry: 'Tiki' is supposed to be a sport of Dieffenbachia x memoria-corsii, and I wouldn't be surprised at all if that were true of the others, at least partly.
I covet 'Reflector,' which in the low-quality pictures I've been able to find appears to take after the picta side of the family. The best picture I've tracked down so far is here (you'll have to scroll down a bit).
'Panther' is another of the "grays," and I like it okay. 'Panther' is weird enough to be kind of neat, though I have yet to see one in very good condition. It has the feathery gray brushstroke pattern of 'Tiki' in the center of the leaf, and then there's another layer under that with yellowish spots like D. picta. I suspect a fairly straightforward cross. I don't consider it pretty, exactly, but I also knew I had to have one, so:
'Tropic Snow' is one of the oldest named Dieffenbachia varieties, and is just a sport of Dieffenbachia amoena discovered at Chaplin's Nursery in Fort Lauderdale, FL. (It appears that Chaplin's is either no longer in operation, has undergone a name change, or is owned by the Amish, as I was unable to find any references to it on the net. The growers' guide is where I heard about it, so blame Lynn P. Griffith, Jr., if there's a problem.) I'm not sure how many actual, honest-to-God 'Tropic Snow' plants are actually out there anymore: a number of sports of 'Tropic Snow' have also been named, among them 'Tropic Sun,' 'Alix,' 'Super Tropic,' 'Lemon Tropic,' and so forth, and I suspect that the actual 'Tropic Snow' may be fading into obscurity. But it's hard to tell, since like I said, they all kind of look more or less the same to me anyway.
There's nice Dieffenbachia porn here, which includes pictures of 'Reflector,' as well as the very 'Sterling'-like 'Green Magic,' the previously-unknown (to me) 'White Flame,' and several others.
So my hope is that anybody who was repelled by Part I of this post has now been pulled at least halfway back with Part II, because they really can be nice plants, and there are some truly spectacular varieties out there too, which are really easy to grow . . . if Dieffenbachias happen to like you. Having been on both sides of their good graces, I admit: they can be heartbreakers, whether they try to kill you or not. But no other plant does what they do half as well, either. So what are you going to do?
Photo credits: my own, except as otherwise noted in text.
1 I'm reasonably certain that 'Camille' here is 'Camille;' it's a pretty distinct cultivar. The 'Tropic Snow' may or may not, in fact, be 'Tropic Snow:' a number of slightly-tweaked varieties of 'Tropic Snow' are out there, and not only are they all only slightly-different from one another, the leaves can have slightly-differing appearances from young to old as the plant grows. It's not impossible; I'm sure South Florida nursery workers who produce them all can tell them apart at a glance. But I haven't had that much practice.
2 In fact, the only time I think peat moss might be your friend is when you're trying to sprout seeds, and even then there are things that work just as well.
3 Not that she looks like she's walking on sunshine right now. But then, by most accounts, being First Lady is not something she ever especially wanted to do, either. I've had trouble settling on a level of sympathy for Mrs. Bush that I feel comfortable with. Do you suppose she knows how much gas costs, or how many casualties the Iraq War has produced? I want to think that she does, and that she's sad about it. But I have my doubts. Hence the varying sympathy levels.
4 It's hard to describe the smell any better than that, because as you can imagine, I do try to minimize the amount of time I spend smelling it. However, sharp and ammoniacal would definitely be in the description somewhere: it's more than just a generic garbagey, rotten smell. It's worse on Dracaenas, somehow: a Dracaena marginata with Erwinia stem rot remains the worst thing I've smelled at this job, or any of my previous jobs (though TEMED, a chemical I worked with three jobs ago, is way up there on the list, and it had a kind of dead-body-slash-vomit aroma. So you can imagine how fun Erwinia is.).
5 Dieffenbachias are capable of branching, sorta, but I'm not sure it's something that all varieties will do: I've only seen it on 'Star Bright,' so far. It looks a lot like the equally-rare Aglaonema branches, which usually happen only after a stem has bloomed. In any case, branches have a tuning-fork sort of appearance, with the two stems following very close to one another; it's not like the new branch goes shooting off in a different direction and gives you an interesting plant. I've seen people say that damage to the growing tip will induce branching in multiple directions, but haven't seen it myself: when I've damaged a growing tip, what usually happens is either nothing, or one new growing tip emerges from the top. Two growing tips would be noteworthy.
6 But then, they have the advantage that they have favorable growing conditions, and their plants will probably re-sucker spontaneously. And even if they don't re-sucker, they can be treated with a chemical called N-6-benzyladenine, which will induce suckering. Indoor growers have neither of these advantages, so if you're thinking about dividing a Dieffenbachia, keep in mind that the divisions will not be as full and fluffy-looking as the original plant was, possibly for a very long time. The husband's 'Tropic Snow' has offset a few times since he bought it, but I don't think any of my Dieffenbachias have ever gotten around to it, even after three years, in a couple cases.