Applying a generous amount of mulch is the most important thing you can do to promote rose health.
The mulch insulates the soil and protects the roots from the stress of extreme temperature changes.
If your weather is really hot and windy, it will slow down the damaging effects of drying out.
Example of a mulched rose bed
The mulch material reduces water evaporation, so the roots are more likely to stay evenly moist.
It also helps to smother the weeds and discourages weed germination. Weeds are not only ugly, but
they compete with your roses for soil moisture and nutrients.It's best to prevent them from growing
in the first place.
I prefer the convenience of purchased organic mulches, such as finely shredded bark.
For most mulches, you'll want to apply a 2-4 inch deep layer in the spring or early summer.
Check the depth of the layer every few months or so, and add more mulch to keep the layer at the proper thickness.
The mulch also adds extra nutrition to the soil around your roses, when the material breaks down and decomposes.