What's Wrong with My Lantana?

Lantana is native to open, tropical scrubland and sets flower buds only when it gets full sun. In partial shade, the plant puts energy into leafy growth and skips blooming almost entirely. Even a few hours of afternoon shade from a fence or tree can cut flower production dramatically.

High-nitrogen fertilizers push Lantana into producing lush, dark-green foliage at the expense of flowers. A plant that looks healthy and full but refuses to bloom in summer is a classic sign. Lantana in good soil rarely needs supplemental nitrogen at all.

Lantana slows new flower production when old flower heads mature into berries. The plant shifts energy toward seed development. Removing spent clusters before they form berries keeps the plant focused on producing the next flush of blooms.

Lantana is drought-tolerant by nature and its shallow, fibrous roots rot quickly when the soil stays wet. Soggy conditions cut off oxygen to the roots, and the plant responds by yellowing its oldest leaves first. The rest of the plant often looks fine until the roots are badly damaged.

Lantana growing in very poor or sandy soil can develop pale or yellow foliage from lack of iron or magnesium, especially when pH is too high. The yellowing tends to show between the veins or across whole leaves uniformly, rather than starting from the oldest leaves at the base.

Powdery mildew shows up as a white or gray dusty coating on Lantana's leaves and stems. Unlike most fungal diseases, it spreads in warm, dry weather when nights are humid and airflow is poor. Lantana planted against a wall or in a crowded bed with little air movement is most vulnerable.

Lantana is a classic whitefly host. Shake the plant and a cloud of tiny white winged insects lifting off is the signature sign. They cluster on the undersides of leaves, suck sap, and leave sticky honeydew that turns black with sooty mold. Heavy infestations cause leaves to yellow and drop.

Lantana naturally converts its lower stems to hard, woody growth over time. Without pruning, the flower-bearing zone retreats to the branch tips and the center of the plant becomes a bare tangle of old wood. An unpruned Lantana after two or three seasons often looks sprawling and sparse despite being alive.