I live in Scottsdale, AZ. We planted several Cape Honeysuckle bushes along our back wall about 4 years ago. We were told they would get very big and bushy within a year, filling in our back wall (which is what we wanted). It is now 4 years later and they have only grown about a foot in height, and have barely spread out. We see these bushes at other homes where the owners say they grow like crazy. They get plenty of direct sun and we have a drip system, so we don't know what the problem is. What can we do to make them flourish?
I would have your soil tested at the local extension service, as it is likely a nutrient deficiency. If you have not provided them with fertilizer in the past, I would recommend going ahead and fertilizing them with a balanced fertilizer. Then, after you get the results of the soil test back, amend the soil based on the deficiencies the tests indicate.