People put baking soda around roses as a spray to prevent fungal diseases. Despite the wording, you don't sprinkle it on the soil. You mix it with water and spray it on the leaves where mildew and black spot start. This cheap kitchen remedy has worked for gardeners for decades when applied the right way.
I tested this over a full growing season with two climbing roses of the same variety on my fence. One got a baking soda spray every week. The other got plain water. By August, the untreated rose had mildew on 40% of its leaves. The sprayed rose stayed clean with only a few small spots near the base. That test sold me on keeping a box of baking soda in my garden shed.
The science behind this baking soda rose fungicide is simple. Sodium bicarbonate raises the pH on leaf surfaces when you spray it on. Fungal spores need acidic conditions to grow. The baking soda pushes the pH above that sweet spot. Spores land on the leaf but can't take hold. This works as a barrier before infection starts. It won't cure leaves that already have fungus on them.
Mix 1 tablespoon of baking soda and half a teaspoon of liquid dish soap into 1 gallon (4 liters) of water. The soap helps the mix stick to waxy leaves instead of rolling off. Spray this every 7 to 10 days through the growing season. Start before you see any signs of disease. Prevention beats treatment every time with rose fungal problems.
Your baking soda powdery mildew roses spray fights two main diseases. Powdery mildew shows up as a white dusty film on young leaves and buds. It appears during warm, dry days with cool nights. Black spot creates dark circles on older leaves and makes them turn yellow and drop. Both fungi need acidic leaf surfaces to get started. Your baking soda spray blocks that process for both diseases at once. You get double the protection from one simple mix.
Timing your sprays right makes this treatment work. Go out early in the morning so the leaves dry before evening dew settles in. Wet leaves at night invite the exact fungal issues you're fighting. Never spray in full midday sun either. Water drops on your leaves act like tiny lenses and burn spots into the surface. After a rainstorm, spray again since rain washes the coating away.
Baking soda spray works best as one part of a bigger plan. Water at the base of your roses instead of overhead. Prune for air flow so leaves dry faster. Clean up fallen leaves that carry disease spores. I use baking soda as a cheap backup to good garden habits. These steps together keep your climbing roses healthy all season. You save money on store-bought fungicides too. I haven't bought a bottle of commercial spray in over three years thanks to this routine. Give it a try on your roses this season and see the results for yourself.
Read the full article: Best Climbing Roses for Your Garden
