1. Keep your soil right
Add a good organic soil improver such as an organic compost or manure to your rose garden soil regularly. A rich soil will help your roses stay strong and fight insects and fungal attacks more effectively.
2. Feed & prune regularly
A regular feeding program (especially during the growing season which is from August to May) will provide all the necessary nutrients required for growth and help guard against diseases. The important thing to remember about all roses is that they need to be pruned; especially in the middle of Winter (after the danger of frost has passed).
3. Water carefully and regularly
Careful attention to watering will minimise fungal problems and provide healthy growth in roses and flowers. Avoid watering the foliage at night as the moisture left on the leaves will help spread fungal problems such as Powdery Mildew and Black Spot.
4. Treat pests and diseases:
There are three main rose diseases that affect these hardy plants at some time or another: blackspot, mildew and rust. If these three diseases can be controlled, the rose garden will be generally disease free.