Planted and grown under the correct conditions, your climbing hydrangea vine can reach 50 to 60 feet in length, once established. A perennial, hardy to USDA zone 5, a climbing hydrangea will naturally lose its leave and die back in the fall, re-leafing the following spring.
The initial indication that your climbing hydrangea may be dying is the color of its leaves. The leaves where your climbing hydrangea is dying back will first begin to turn yellow or lime green in color. The leaves may also have an appearance of yellow with the veins of the leaf remaining a darker green. In severe cases, all the leaves of your climbing hydrangea turn yellow, fall off and your vine completely dies.
Climbing hydrangeas are hardy and generally not susceptible to many pests and diseases except a condition called chlorosis. Chlorosis is characterized by the leaves of a plant turning yellow because it cannot receive adequate chlorophyll. If not corrected, chlorosis can kill a climbing hydrangea vine.
There are several causes of chlorosis that could be affecting your climbing hydrangea. Possible causes could be excessive water and poor drainage, damaged or compacted roots, nutrient deficiency or the most common factor, a high pH, or high alkaline, soil. Climbing hydrangeas, like all hydrangeas, grow best in slightly acidic, or lower pH, soils. High alkaline based soil restricts a hydrangea plant from having the ability to absorb the needed minerals, particularly iron, through its roots and, thus, causes the plant to be inflicted with chlorosis.
The process of elimination is an effective method to identify what is causing the chlorosis in your climbing hydrangea. Begin by eliminating the easiest to identify, poor drainage. Soggy, water-saturated soil for long periods of time is an indication your soil is not draining well. Compacted and heavy clay soil causes root compaction and root damage. To determine the pH level of your soil, use a home soil test, or contact your county agriculture cooperative extension office for testing.
The addition of organic matter to the soil, tilling, aeration and mulching will help control chlorosis that is caused by root compaction, root damage or poor drainage. The organic matter can also contribute to adding nutrients and slightly lowering the pH of the soil. But, by the time chlorosis has been detected and your climbing hydrangea is dying, quick action needs to be taken to feed the plant the missing nutrients. Spraying applications of the needed nutrients and minerals onto the leaves will temporarily solve your chlorosis problem, but will need to be reapplied as new leaves appear.
Soil amending can also be done after you have had your soil tested for deficiencies. Regular testing after amending your soil should be done, with additional supplements added as needed. A longer lasting treatment is to use a trunk application of the nutrients and minerals. This entails drilling holes into the trunk--the number is determined by the size of the trunk--and either inserting capsules of nutrients or liquid-filled tubes. A professional should be utilized for trunk applications for best results.