Johnny Jump-ups (Horned Violets) are some of the most versatile little flowers out there—you can plant them pretty much year-round! They look amazing in balcony window boxes, patio pots, or even as a colorful groundcover tucked under taller perennials. These beauties are generally tough as nails and super easy to care for, but even the hardiest plants have a nemesis: powdery and downy mildew.
Powdery vs. Downy Mildew
Even though Johnny Jump-ups are usually healthy, these fungal diseases can occasionally crash the party. It’s important to know the difference between the two types of mildew so you can treat them the right way.
Powdery Mildew
If you notice a white, flour-like coating on your leaves and flowers during the summer, you’re likely dealing with Powdery Mildew. Gardeners often call this the “fair-weather fungus” because it loves warm, dry days. As soon as you spot it, snip off the infected parts and toss them in the trash—never the compost bin, or the fungus will just hang out and spread! To treat the rest of the plant, try a simple milk spray: mix one part fresh milk with eight parts water. The natural microorganisms in the milk are surprisingly great at fighting off the fungus.
Want to keep Powdery Mildew away in the first place? Here’s the game plan:
- Make sure your Johnny Jump-ups are planted somewhere with good air circulation.
- Keep the soil moist but not soggy.
- Use well-draining soil.
- Don’t over-fertilize, especially with high-nitrogen blends.
- Give them some breathing room (space plants 4 to 8 inches apart).
- Plant “bodyguards” nearby like basil, chervil, or chives, which can help deter mildew.
- Keep the area weeded, as fungus loves to hide in overgrown patches.
Downy Mildew
Unlike its cousin, Downy Mildew is a “bad-weather fungus” that thrives when it’s rainy and humid. It looks a bit different, too: you’ll see a white or grey fuzzy growth on the undersides of the leaves, while the topsides develop yellow spots. Eventually, the leaves will wither and drop off, and the infection can take over the whole plant. Just like before, any infected parts should go straight into the garbage.
The good news? You can fight Downy Mildew with some DIY natural remedies. These sprays work wonders:
- Horsetail tea: You can find this at most garden centers.
- Tansy tea: Boil about 3.5 oz of dried tansy leaves in a quart of water for 30 minutes, then strain.
- Garlic spray: Crush 4 cloves of garlic into a quart of water, boil for 15 minutes, and strain.
Just dilute these mixtures with a bit of extra water and give your Johnny Jump-ups a good misting to help them bounce back!
