Phalaenopsis gigantea - long term growing project

[estación seca]

During a recent spell during which I couldn't take normal care of my plants I've killed my fifth seedling.

Over the last few years I've bought four of these, from two different vendors, in 4" pots, with sphagnum or a sphagnum/bark mix, and two leaves each. Each looked healthy, but not amazingly so, on arrival. Not one had beautiful roots. I kept them in my humid, warm sunroom and tried not to let them dry out. Each did dry out completely at one time or another, but in each case that happened months before it died.

The first three never made any attempt to grow a new leaf, nor new roots, despite monthly treatment with KelpMax. I kept them moist and fertilized as I fertilized my other Phals.

The next plant was a $5 bare-root plant from Ecuagenera. I was willing to spend $5 extra with a larger order, and see what happened. It arrived with only one root, broken at the base of the plant. I put it in a humid, moist container on top of sphagnum moss and sprayed with KelpMax, but it never grew. It took about 9 months to wither away. I recommend people not buy a bare-root Phal. gigantea from Ecuagenera. Of course they never responded to my E-mails.

The last plant arrived last fall. Because my sunroom regularly falls to 60 F / 15C I overwintered it in a large vase with a heater underneath and a cover. It dropped one of its two leaves, then began making a new leaf in midwinter. When the sunroom was good and humid I moved it there. The new leaf continued slowly growing. I was out of town for almost a week this spring. When I returned the container was almost but not quite dry. The new leaf never grew after that. Recently for a 3-week period I was only able to care for my plants about once a week. On the second visit I found the plant with moist medium, but leafless and dead. This plant never made new roots during the time I owned it. As I mentioned, not one of these five plants made any new roots.

I'm not sure what the problem is. Can drying out once be fatal for these, even in very warm and humid environment? Can it take months for them to die after drying out? Why has none of five plants ever grown a new root? Are some strains of this plant easier to grow in cultivation? Could fertilization have anything to do with it?

[K-Sci]

Originally Posted by estación seca

I'm not sure what the problem is. Can drying out once be fatal for these, even in very warm and humid environment? Can it take months for them to die after drying out? Why has none of five plants ever grown a new root? Are some strains of this plant easier to grow in cultivation? Could fertilization have anything to do with it?

I've found information on how to grow Phalaenopsis gigantea often conflicts, but several sources say it must be kept constantly moist.

Norman's orchids is very successful growing the plant from seed to maturity. Their growing instructions are scattered. In one place he says to allow the plant to "dry slightly", between watering. What that means is hard to know with certainty, but I would assume it means not to keep it wet but also not to let it become bone dry. Norman's orchids provides growing instructions with their alba gigantea, which can be read here.

Phal. gigantea var alba (gigantea var alba ' Prince ' x gigantea var alba ' Ta-Wai') / Orchids.com

One successful grower has a mature plant in sphagnum in a very large pot hung at an angle from the ceiling. I can't imaging that that much sphagnum ever gets completely dry. This grower remarked that his plant flowered then flowered again shortly after repotting. This would seem to contradict the "resents repotting' reputation. I think it is possible that this plants reputation for resenting repotting could be because new media such as bark can be very dry and hard to whet, causing roots to become too dry.

Some say it can't tolerate the levels of fertilizer typically used for orchids. Some advocate foliar feeding over drench fertilization.

The native environment is very warm with average nighttime lows in the low 70s. It is possible that regular lows in the 60s could be fatal and may account for the reputation for growing very slowly. The reputation for being easily rotted could also be accounted for by growing it too cool. Few greenhouses maintain low nigh time temperatures in the 70s in the winter.

-Keith

[camille1585]

Originally Posted by estación seca

I'm not sure what the problem is. Can drying out once be fatal for these, even in very warm and humid environment? Can it take months for them to die after drying out? Why has none of five plants ever grown a new root? Are some strains of this plant easier to grow in cultivation? Could fertilization have anything to do with it?

I don't think drying out is the cause of the problems you have. I've had my plant 7 years now, and it went through many repeated bouts of neglect in the first 2 years when I was finishing my PhD, and after that, every summer it goes 3 weeks without water when I'm on vacation. Despite this it has always managed to put out 1-2 new leaves each year, and continued to grow roots.... In fact that giant new root in the most recent photo I posted grew during my vacation this August, when it didn't get any water.

My experience with this species (in a pot) in my fairly average temp/humidity climate is that it likes a substrate a bit more airy than I use for my other Phals (it was in rather chunky bark the first 5 years, leca the past 2 years), and it seems to really like fast wet/dry cycles. So similar to what it would get on a mount. I have also often read/seen photos of them growing in sphag and kept fairly damp so that does work too, but don't have experience with it. I don't know if my methods are optimal, but the plant is often happily growing so it can't be that wrong.

As to some strains being better than others I don't know the answer to that either, but seeing the number of plants you've had it's hard to imagine that all of them are poor strains!