My zinnias and gladiolas were quite spindly this year. The zinnias grew 5 feet tall and the gladiolas reached 6 feet. The stems were so weak they could barely support the blooms, even with the help of stakes.
Lack of light or excess nitrogen can cause the growth you describe, so take a look at the area’s conditions. Have your trees matured and started shading these plants? Perhaps a new fence, shed or other addition is blocking some of the needed sunlight.
Next, take a soil test to find out what, if any, fertilizer is needed. Avoid high-nitrogen fertilizer that can promote excess growth. And finally, monitor the soil’s moisture. Excess rain or watering can lead to spindly growth and disease problems.