Oxalis will appreciate a soil that you can keep moist but will still have plenty of aeration. I tend this plant for my mom in a south window behind shears & use Foliage-Pro 9-3-6 on it because it contains ALL the essential nutrients, but you would do well with any other 3:1:2 ratio fertilizer (like MG 12-4-8 or 24-8-16, both 3:1:2 ratios as well).

No matter what you do, the plants will at times look ratty. They may be telling you they need a rest. I've had good luck withholding water at that time for several weeks and letting the plants die back before starting my water/fertilizer regimen again.

Burned leaf margins could be a sign that soluble salts levels in the soil are too high, or you're using too much fertilizer. Fertilize every couple of weeks with a 1/4 strength dose ONLY when the plants are growing well, unless you're using a soil that allows you to water profusely at every watering (so at least 10-15% of the total volume of water used exits the drain hole), in which case you can fertilize more frequently at low doses with no concern for salt build-up.

If you'll contact me off-forum, I have something else I'd like to propose.

Al

If you could tell me how to kill my oxalis without killing the plants it's growing in I'd be happy ;) At the moment I have oxalis in my orchids, whilst the orchids look shoddy, the oxalis is flourishing. Maybe a cool down time would help you keep it looking alive for a longer time.

PS last year I found an oxalis for $75 about the time of St Patricks Day. I almost died laughing.

I know, huh! I HATE that stuff (the weedy kind). WAP! I usually get a small paint brush & paint round-up on the stuff in my containers when I feel ambitious.

Al

Talpa...
As soon as you said salts, I was like, "Oh duh!". I have hard water here, but since I've lived most of my life with soft water, it didn't cross my mind. I'm guessing that could be why my Shamrock is crinkling, my Christmas cactus is dropping buds, and my Poinsettia is shedding leaves.
Maybe I should use distilled water from now on... would something like a Brita pitcher help for filtering the hard water so I don't have to buy jugs of water all the time? Or are those a waste of time?

The best solution lies in your choice of soil. If you are using a soil that drains freely enough that you can water profusely every time you water w/o risking root rot, your irrigation water will rarely be enough to cause a problem. It's when you choose to use a soil so poor you have to water in sips small enough to prevent root rot that salts accumulate in the soil. Yes, distilled water, water saved from a rain/snow source, or a dehumidifier will, practically speaking, eliminate salts from your water source; but again, the right soil with proper watering habits (flushing the soil each time you water) will provide superior aeration and eliminate concern for salt build-up. ;o)

Al

Oh, ok. Well, it's draining well, so I'll turn my ceiling fan waaaay down. That's my other other other guess. Danged place is so hot though sometimes lol

Ceiling fan? To what purpose?

Al

Well, my ceiling fan makes quite a breeze since my apartment is really small. I was told that my poinsettia didn't like breezes, and I figured that whatever is good for the goose is good for the gander. :)

Don't lose sight of the fact that Mother Nature gives little consideration to turning the fan off when the wind feels like blowing. The breezes you should worry about are not the warmish air the ceiling fan is destratifying, but rather the cold drafts that find their way in through windows and doors left open to winter's chill. ;o)

Al

Oooh... ok. That isn't a problem then.
I think I have a classic case of overwatering. The soil is always wet, and I do make sure that the water drains well. My mom planted the shamrock, and she does know what they like. I haven't fertilized the soil whatsoever.
Note to self: When you are drunk and going "Ohh! Hello plants! Do you want some water???", the answer should be no.