Soaker hoses can be the best method to keep the moisture from the leaves and flowers. These methods are great when you want more efficient water delivery at the very base of the plant without needing to get the entire foliage wet.
Lay the hose around the plant, leave it on for about 30 to 45 minutes and wait until the soil is moist but not too wet. Hook your regular hose to this, and cover with mulch. Others may use drip feeders to retain moisture throughout the day.
When planted in pots, you need to water the Climbing hydrangea using a watering can. Wait until you see that the water is dripping down the pots at the bottom part. The portable cans can help you reach the soil and let the water penetrate the roots deeply so they can grow better.