Help me save a dying houseplant!

September 19, 2009 6:45 PM

Help me save my vanilla plant! Its leaves are turning black and rotting from the bottom up. Too much water? Not enough? Lost cause? Help me green thumbs!

I got a vanilla planifolia vine from logees and it came with a root ball. I planted it in coconut chips as instructed, and gave it a trellis to grow up. It was doing fine until I had a friend plant sit while i was in the hospital. Now the roots have died and the vine is now separate from the roots. the bottom most leaf is dying, turning black and rotten looking. Meanwhile, the other leaves seem a bit wrinkled.

The plant is indoors, in 70 degree temperature under plant suitable lighting approximately eight hours a day.

What can I do to help keep this plant alive and happy? I've been misting it once a day with water with a tiny bit of fertilizer in it, but its too soon to say if that has been helping or not. The leaves seem less wrinkled than before though.

What do you think?

posted by gilsonal to Home & Garden (4 answers total)

It sounds like a "root rot", a generic term for some (usually) fungal pathogen attacking a weakened plant's roots. It's most often a byproduct of too much water, but I think in your circumstance, it sounds like the fertilizer. If you have any roots left attached, you could try taking it out of the pot, removing all of the growing medium, cutting off all of the blackened or discolored roots and tissue, and putting what may be left into some new medium, especially one that doesn't hold too much moisture. The coconut may be fine, but perhaps it's degraded enough to turn into compost that would hold moisture more? You probably shouldn't have been fertilizing it daily, that can cause problems of salt buildup and high ph. If it has a fungus, you may try treating it with something, apparently Pseudomonas fluorescens is used as a biocontrol (though I don't know how the hell you'd find it). It could be fusarium or phytophthora, they're all really tough. I've heard of using hydrogen peroxide to sanitize roots, but I really don't know if that works. Has it sprouted any leaves along the stem that climbs, especially ones with rootlets growing on them? If so, you can just cut it off and start a new plant. These are called "keiki".
Is it under artificial grow lights? Is this what you mean by "plant-suitable"?
posted by Red Loop at 8:36 PM on September 19, 2009

I agree with the root rot as a likely diagnosis. I disagree that daily foliar feeding (spraying with fertilizer fortified water) is likely to be a serious contributing factor, particularly if you are only misting the foliage, if the amount of fertilizer is very small, and if you give it an occasional clean mist to clean off residue.

If the roots have truly died off and are fully separate from the vine it's very unlikely you will save the plant. It is probably not going to be able to take in enough nutrients through the foliage and aerial roots to sustain enough new root growth to re-establish it. If there are any healthy roots left it may pull through, the less roots there are, the less likely it will survive.

Agree with Red Loop, remove all dying and blackened material and repot in fresh media (use a fresh pot as well to avoid fungal contamination). You haven't said how long you've had it, have you been repotting it? I'd guess it probably would need it every other year (not being acquainted with this particular species). The problem could have been developing for a while if the roots were staying too wet for some reason.
posted by nanojath at 9:09 PM on September 19, 2009

I've only been misting and fertilizing since the roots rotted, so I don't think thats contributing to the original problem, but it may be exacerbating it. It is under grow lights. I'll try repotting and see if I can help it pull through. Its a fairly new plant, and the roots are all gone with the exception of aerial roots, so its not looking good. thanks!
posted by gilsonal at 5:55 AM on September 20, 2009

Plant pathologist weighs in: The key thing to remember is that a vanilla plant is an epiphyte; it doesn't grow in the ground in nature; it hangs from the bark of a tree. The orchid root is thick and spongy and adapted to pulling in moisture from dew, mist and raindrops; it can't tolerate continuous wetness. Fortunately, orchids produce adventitious roots along the stem, so if your plant can hang on for a while, it will be able to produce new roots. The leaves are wrinkled because they are dehydrating; orchids leaves are also adapted to storing water, and as their reserves run out, the leaves shrink. So take the part of the vine that's still healthy (with green tissue) and cut off anything that looks brown or rotten; you can even dip that new cut in 10% bleach to make sure it's sterile. Then mist the plant frequently for the next few weeks (twice a day?). If the leaves stop looking wrinkled you'll know they're getting enough water. You might want to keep the plant in a humid environment like your bathroom. You'll see the stubs of new roots as they develop, and as soon as they get a few inches long, the plant ought to be on the road to recovery. The problem will be how to repot: I'd stick the base of the vine in a pot filled with big chunks of bark. I don't know what you mean by coco chips, Coconut hull fiber is an acceptible orchid pot medium, but cocoa chips (the ones that smell like chocolate) will retain too much moisture. You then need to pretend you're in a tropical rain forest: let it "rain" on the orchid roots, but be sure the potting mix is loose enough that the roots can get good air circulation and can dry out between waterings. I water my orchids twice a week.

I've been looking at that vanilla plant in Logees catalog, and I keep deciding that my house doesn't have any place that's warm enough and humid enough for me to buy one.

Good luck!
posted by acrasis at 7:48 AM on September 20, 2009