Help with my houseplants!

5 years ago

Hi there,
Recently I have had issues with several houseplants that were all on the same shelf (touching). An alocasia (the first victim), a syngonium, and a monstera deliciosa. The Alocasia was the first to show signs of a problem, with almost all of its leaves now gone. They would develop a weird, almost silvery pattern on the underside of the leaf with what looks like tiny black dots that you can feel. Then the top of the leaf would start to be affected. Starting as a brown spot that would turn yellow, eventually the entire leaf would die. And a very similar pattern in the other plants as well. All the lower leaves first.

Featured Answer

tapla (mid-Michigan, USDA z5b-6a)

5 years ago

All the leaves show evidence of oedema, a physiological disorder that can affect all plants. It occurs when the plant takes up more water than it can rid itself of via the process of transpiration. The word itself means 'swelling', which is usually the first symptom, and comes in the form of pale blisters or water-filled bumps on foliage. Under a variety of circumstances/cultural conditions, a plant's internal water pressure (turgidity) can become so high that some leaf cells rupture and leak their contents into inter-cellular spaces in leaf tissue, creating wet or weepy areas. Symptoms vary by plant, but as the malady progresses, areas of the leaf turn yellow, brown, brown with reddish overtones or even black, with older damage appearing as corky/ scaly/ ridged patches, or wart/gall-like bumpy growth. Symptoms are seen more frequently in plants that are fleshy, are usually more pronounced on the underside of leaves, and older/lower leaves are more likely to be affected than younger/upper leaves.

Oedema is driven primarily by excessive water retention in the soil, and can be intensified via several additional cultural influences. Cool temperatures, high humidity levels, low light conditions, or partial defoliation can individually or collectively act to intensify the problem, as can anything else that slows transpiration. Nutritional deficiencies of Ca and Mg are also known contributors to the malady.

Some things that can help you prevent oedema:

* Increase light levels and temperature if temperature is below 65*F.

* Monitor water needs carefully – avoid over-watering. I'd heartily recommend a soil with drainage so sharp (fast) that when you to water to beyond the saturation point you needn't worry about prolonged periods of soil saturation wrecking root health/function. Improving your soil choice is very often the key that unlocks the solutions to many potential problems.

* Avoid misting or getting water on foliage. It slows transpiration and increases turgidity.

* Water as soon as you get up in the AM. When stomata close in preparation for the dark cycle, turgidity builds. If you water early in the day, it gives the plant an opportunity to remove (for its own needs) some of the excess water in the soil.

* Put a fan in the room or otherwise increase air flow/circulation. Avoid over-crowding your plants.

By what metric do you decide when it's time to water?

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Comments (8)

Shauna Luce
Original Author
5 years ago

Sorry, I couldn't figure out how to add these initially.
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Shauna Luce
Original Author
5 years ago
Hi, thanks Al for all that information! Generally I am an under waterer. But I do often have a humidifier on, and not the best lighting for my plants. I do try to use a water meter to see if my plants are needing to be watered. I am wondering if maybe transfering my plants over to a better draining soil?
tapla (mid-Michigan, USDA z5b-6a)
5 years ago
I do try to use a water meter to see if my plants are needing to be watered. Water meters don't measure moisture, they measure electrical conductivity. Clean the probe and dip it in a cup of distilled water and note it reads 'DRY'. Add some ions by sprinkling in some table salt and you can watch the needle move to wet. Using a wooden 'tell' to tell you when to water is much more reliable. Water when the medium is almost dry, but not quite ..... unless you have the occasional plant that needs the entire soil column to remain moist if the plant is to maintain its turgidity (not wilt). Also, the often parroted advice to "water when the top inch or two of the grow medium feels dry" is a recipe for over-watering. What's important are moisture levels deep in the pot where the fine roots which do all the plant's heavy lifting reside. More about using a 'tell' below. I am wondering if maybe transferring my plants over to a better draining soil? There is a huge difference in the effort:reward ratio between growers using a medium they have to battle every day for control of their plant's vitality and those who have learned to make, amend, or recognize a medium that will work for you instead of at cross purposes to your best intentions.

You mentioned being an under-waterer, which might simply mean your medium stays wet/soggy for an inappropriately long interval after a thorough soaking. IOW, over-watering, if you water correctly, is an inherent limiting factor in all media that hold too much water, even if the grower tends to forget to water on time. You can't make up for the limitations imposed by the grow medium being too wet for long intervals by ensuring it also remains too dry of inappropriately long intervals. They can't cancel each other out, it's just stress added to stress.

If you're interested in learning more, I can put you onto some things I've posted here that should be enlightening if you're in an 'I'm enthusiastic and want to learn more' mode.

Aeonium in a cap from a tube of Chapstick

Al
Kathy Hamlin
5 years ago
tapla, is there a hole in the bottom of that chapstick cap? I love it!
tapla (mid-Michigan, USDA z5b-6a)
5 years ago
Thanks, Kathy. Yes, there is a hole. I heated a nail with a propane torch and stuck the hot nail through the bot bottom, then filed the hole flush to the bottom so the cap rests flat on a flat surface.

about 1.25" tall ^^^

Use the nap of the terry towel to judge how small this ^^^ cacti is - roughly tall and wide as a nickel.

.... in a white oak acorn cap

dollar store salter ^^^

Chapstick cap ^^^

sempervivum foreground, then another aeonium in back - same one as in image above this.

Al
angela branson
5 years ago
My Voodoo lilly has started turning yellow and brown and has a sticky film on the leave. Can someone help tell me what's wrong? I've searched and googled but no real help to tell me what's wrong.
angela branson
5 years ago
My Voodoo lilly has started turning yellow and brown and has a sticky film on the leave. Can someone help tell me what's wrong? I've searched and googled but no real help to tell me what's wrong.