|The leaves on my verbena are starting to yellow and the plants aren't producing any blooms. These plants are planted in the ground and have been given plant food regularly. The verbena in pots are doing better, although they aren't producing blooms like when they were first purchased. Any idea what may be causing the yellowing leaves and lack of blooms?|
Yellow leaves can be caused by many things including lack of nitrogen, insufficient light, water-logged soil (plant roots need oxygen to thrive), dry soil, or iron deficiency. If the older bottom leaves are yellow, but new growth is green, it's usually a lack of nitrogen. If new leaves are yellow, with green veins, it's usually a lack of iron. (Lack of nitrogen is a more common problem than lack of iron.) Soil should be kept moderately moist (but not wet). Finally, transplant shock can contribute to yellowing. If new growth shows up as green, that might be the problem. Try to isolate each of these possibilities one at a time to determine the problem.
When fertilizing, apply it at the edges of the plant, where the feeder roots are actively taking up water and nutrients. Use a fertilizer with a higher middle number (phosphorus) to promote bloom. Not knowing which verbena you have and there are so many, but some may have shorter bloom periods than others. Deadhead spent flowers to increase the bloom period.