Calla Lily Care Tips: How to Stop Stems from Curling

I don’t know about you, but I’ve always wondered why the calla lily stem curls at the end a couple days after being cut. Honestly, I’ve always thought it looked kinda cool—like the flower was trying to add its own little flair. Well, today my curiosity got the best of me, so I decided to investigate. Apparently, it’s due to something called osmotic pressure in the cells. What?!?! Ugh, now I have to go look that up. “The minimum pressure needed to stop the net flow of a solvent across a semipermeable membrane.” Oh, perfect. Totally cleared it up. 🙃

With a little more digging, I think I finally came up with an explanation that my non-science brain can actually process. Basically, water naturally wants to move from where there’s more of it to where there’s less of it. Since there’s less in the stem of the calla lily, the water rushes up the stem, making it puff up and sometimes split. In other words, the calla lily stem doesn’t have enough osmotic pressure to put the brakes on the water. Osmotic pressure is basically the flower’s “doorman,” and the calla lily’s doorman just isn’t strong enough to stop the crowd from rushing in.

When I set out to quickly Google why calla lily stems curl, I did not expect it to turn into a full-on science lecture. I mean, I failed chemistry in high school, and here I am reliving the nightmare.

Anyway… I’ve made my own very professional, definitely-not-just-winging-it conclusion. From my years as a florist, I know water moves up flower stems faster if it’s warm. This is why we usually use warm (but not hot—no need to cook them!) water when conditioning roses. Roses have dense stems, so the water needs a little extra help. Translation: rose stems have stronger osmotic pressure than calla lily stems. Calla stems, on the other hand, are much softer, so water rushes in too easily, causing the curling and splitting. My hunch? Cold water might be the way to go with calla lilies—keep them chill and they might behave better.

I also came across some other tips. One florist recommended leaving calla lilies out of water for a little while before putting them in. This lets the stem close up at the ends a little, which boosts its osmotic pressure. (I’m feeling really smart now—like, honorary PhD smart!)