Hello, it's me, your Osteospermum. I'm trying my best out here, but my leaves are turning yellow, and that's my way of telling you I'm not feeling my best. Let's figure this out together. It's usually not just one thing, but a conversation we need to have.
This is the most common reason I feel unwell. You might be loving me a little too much with water. My roots need to breathe! If I'm sitting in constantly soggy, poorly-drained soil, my roots will suffocate and start to rot. Once they rot, they can't deliver water and nutrients to the rest of me, and my leaves will turn a sad, yellow color, often starting from the bottom. Please feel my soil before watering. I like a drink only when my top inch of soil is dry to the touch. And make sure my pot has a hole for the extra water to escape!
I put on a big, colorful show for you all season long, and that takes a lot of energy. If I'm planted in soil that isn't very rich, or if I've been in the same pot for a long time, I might use up all the available food. Without key nutrients like nitrogen, iron, or magnesium, I can't produce the green chlorophyll that keeps my leaves a vibrant color. They'll start to fade to yellow, sometimes with green veins. A light, balanced liquid fertilizer every few weeks during my growing season can make a world of difference for me.
While I don't like wet feet, I am a living thing and I need water to survive. If I'm left to wilt repeatedly in hot, dry sun, my leaves will get stressed, become crispy, and turn yellow or brown as they give up. I'm fairly drought-tolerant once established, but consistent neglect is hard on me. Try to keep my soil evenly moist, not swinging between a swamp and a desert.
If I'm living in a container, my roots might have run out of room. When the pot becomes a tight mass of roots, there's not enough soil left to hold water and nutrients. Every time you water, it just runs straight through, and I get nothing. This stresses me out immensely, leading to yellowing leaves and stunted growth. If you see roots circling the inside of the pot or growing out the drainage hole, it's time to gently move me to a new home that's just an inch or two larger.
Sometimes, the problem is tiny invaders. Aphids or spider mites might be sucking the sap from my leaves and stems, stealing my nutrients and causing yellow speckling or overall yellowing. Check my underside! Fungal diseases can also cause yellow spots or patches. Good air circulation around my leaves and avoiding watering from above (which wets my foliage) helps keep these issues at bay. A strong spray of water or an insecticidal soap can usually evict those pesky pests.
