heavier clay, once a week may be enough if you water slowly so it penetrates 8 to 12 inches down. I use a hose on a slow trickle for 15 to 30 minutes at the base rather than spraying the leaves. Wet foliage overnight invites trouble, especially powdery mildew and leaf spot. Young first-year clematis need closer watching and usually dry out faster than older, settled-in plants.
3. Mulch the root zone to keep roots cool and evenly moist
One of the oldest clematis tips is still one of the best: cool roots, sun on the vine. In August, I refresh mulch if it has thinned out to less than 2 inches. A layer 2 to 3 inches deep of shredded bark, compost, leaf mold, or clean straw helps hold moisture, buffers temperature swings, and keeps weeds from stealing water.
Keep the mulch about 2 inches back from the stems
