Rhododendrons are evergreen bushes that bloom in the spring. They prefer filtered sunlight and need soil that drains well. If you are planting rhododendrons, till in a few inches of organic matter such as compost or peat moss to improve drainage. While rhododendrons are easy to care for, they have a few watering needs that must be addressed.
Spread 2 or 3 inches of mulch under the rhododendrons; use pine bark, wood chips, leaf mold or pine needles. Extend the mulch under even the widest branches, called the drip line. Do not mulch directly next to the stem; leave a 2-inch space.
Water your rhododendrons only after the soil dries. Begin watering in the spring when new growth appears. When the leaves roll up, it is an indication they need an inch or so of water. During hot summer days, wilting is normal in the afternoon and does not necessarily indicate the bushes need water.
Water your rhododendrons less, if at all, during the fall. Keeping the bushes dry in early fall will help them prepare for winter. Water them one more time, however, right after the first killing frost.
During the growing season, water newly planted or transplanted rhododendrons for the first month so that the soil is evenly moist. Transplanting rhododendrons in the winter is best since they are dormant.