Plants have specific ways of telling gardeners that there is a problem but not all plant symptoms lead us directly to the cause. During drier conditions, we often use wilting leaves as an indicator that water is needed. This can be a reliable symptom that the soil is lacking moisture but it is not always the case. Wilting leaves and herbaceous branches actually tell us that there is not adequate water in the plant. It does not necessarily indicate lack of moisture in the soil.
There can be many reasons why water is not being absorbed by roots and moved to tissues in the plant. The obvious place to start is by checking soil moisture. If soil is powdery several inches deep around the plant, water is likely needed. However, if you ball the soil up in your hand and it holds together, there may be another reason for lack of water reaching the upper plant parts. The harder part is determining why the root system is not taking up water. Causes can be a rotted root system from too much water, a poorly developed root ball that has circling or kinked roots, and even problems in the soil such as compaction. Insects, diseases, and other pathogens can also injure root systems preventing the uptake of water.
So before automatically grabbing the hose or turning on the sprinkler, do a little soil investigation to make sure that the plant wilt is really indicating lack of water in the soil. If you need help in your diagnosis, always contact your local Extension office.