Why are my rose blooms turning brown before they open?
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It’s disheartening when your roses are turning brown before they open, I know the feeling as it happened to me on many occasions over the years. They’ve grown fully so why don’t they just bloom in full colour? The answer is probably a fungal disease called botrytis blight or a disorder called flower balling. Read on to learn what to do about these problems.
Flower balling (rose balling)
What is flower balling?
Flower balling is a disorder that’s caused by cool and wet weather. It affects fully developed buds (mainly in roses and peonies) and stops them from opening. Cool and wet weather in the summer saturates the outer petals of the flower buds.
The sun then comes out, and dries everything up. This fuses the flower buds into a tight shell with an outside papery covering. But if you open the flower buds, the inner petals are normal.
How to spot flower balling
Look for tightly closed flower buds. Along the way, the rose flower buds turn brown and crispy. The buds either drop off the plant or stay hanging on. Those that remain are susceptible to botrytis blight.
What to do
Remove the affected buds as soon as you notice them. Leaving them just encourages botrytis blight to move in. Make sure that there’s good air circulation in and between your rose trees so any wet plants can dry off quickly. (See How and when to prune roses for details about how to do this.) And always water the roses at the base of the trunk and never over the foliage or flowers.
If there’s going to be a big rainstorm or a few days of rain, build a temporary shelter over your rose bushes.
What is botrytis blight?
Botrytis blight is a fungal disease that primarily affects the buds of double flowers, including roses and peonies. It usually occurs in wet weather, so it is often found in rainy summers. The flower buds develop normally but don’t open.
How to spot botrytis blight
After flower balling, the roses turning brown and dry encourages this fungal disease to move in.
If you move the outer petals apart, the inner ones appear to be normal. The buds may drop off or may hang on to the plant. If they stay on the plant, look out for grey mould that causes the buds to rot.
What to do
Prune away any affected buds (with a sterilised and sharp cutting tool). Deadhead the rose tree at regular intervals to discourage the disease. And use a natural fungicide such as pyrethrum oil or neem plant oil.
I also have another guide on 12 of the most common rose problems which may be useful here. Most of these can be prevented if you follow my guide on caring for roses here to keep them in good health.
I also have a guide dedicated to pests and diseases that attack roses here including black spot, rust, mildew, aphids and rose sawfly.