Batten Blooms
PL. —Ceratotheca triloba 'Alba'Botanical illustration — drop image
Ceratotheca triloba 'Alba'

South African Foxglove

SpringSummerFall
2a–11bHardiness zone
Peak bloom windowZone 6b · frost-offset weeks
Winter
Not in bloom
Spring
Peak bloom
Summer
Peak bloom
Fall
Peak bloom
Peak bloom
In bloom
Background

Ceratotheca triloba 'Alba' is a fast-growing annual or tender perennial from southern Africa, in the sesame family (Pedaliaceae). It produces tall, branching stems densely set with white tubular flowers that closely resemble foxglove (Digitalis), giving it strong vertical presence in sunny borders. Plants reach 4–6 feet in a single season without needing rich soil or intensive care.

It thrives in full sun with average, well-drained soil. Hot summers drive the best growth, and the plant tolerates heat and moderate drought far better than true foxgloves. In zones below 9, it is grown as a warm-season annual — start seed indoors 6–8 weeks before last frost or direct-sow once soil reaches 65°F. Seeds need light to germinate and must not be covered. Mature plants develop a taproot and resist late transplanting, but self-seeding is reliable in warm climates.

Young leaves of C. triloba are cooked and eaten as a leafy vegetable in Botswana and other parts of southern Africa, used similarly to spinach.

Good companions
ZinniaCosmosSalviaSunflower
Care guide
SunFull sun
WaterModerate
SoilWell-drained, average fertility
Spacing18–24 in
Height48–72 in
Zone2a – 11b
Direct sow
Seasonal tasks
spring
sowStart seeds indoors 6–8 weeks before last frost in cell trays; surface-sow and do not cover — seeds require light to germinate. Maintain 70–75°F until sprouts appear.
sowTransplant hardened-off seedlings after last frost; remove from cells carefully and disturb roots as little as possible.
sowDirect-sow into warm garden soil, pressing seeds lightly onto the surface without covering. Thin seedlings to 18–24 in apart once they carry two true leaves.
summer
cutInsert a stake beside plants when they reach 2 feet if the site is wind-exposed; tie stems loosely. Plants in sheltered spots usually self-support.
watchCheck stem tips for aphid colonies through midsummer; dislodge with a strong water spray or apply insecticidal soap.
cutCut spent flowering stems back to the nearest side-shoot to encourage continued lateral branching into fall.
fall
cutCollect dried seed pods before they split open if saving seed for next season; store in a cool, dry location.
Common problems

Powdery mildew

Symptoms

White or grey powdery coating on leaves — usually starting on older growth in humid conditions or when nights cool.

Treatment

Improve air circulation by thinning plants. Apply neem oil or potassium bicarbonate spray at first sign. Avoid overhead watering.

Damping Off

Symptoms

Seedlings collapse at the soil line with thin, water-soaked stems; seeds may fail to emerge or rot before sprouting.

Treatment

Sow in well-draining mix, avoid overwatering, and ensure good airflow. Remove affected seedlings and let the surface dry between waterings.

Root rot

Symptoms

Plants wilt, yellow, and stunt even in moist soil; lower stems and roots turn brown, soft, and mushy and the plant may collapse. Most common in heavy, wet, or poorly drained ground.

Treatment

Improve drainage and stop overwatering, and never plant too deep. Lift and destroy badly affected plants along with the soil around the roots. Grow in raised or free-draining beds to prevent it returning.

Botrytis (grey mould)

Symptoms

Grey fuzzy mould on petals and stems, worst in cool wet conditions.

Treatment

Remove affected parts immediately. Improve air circulation. Avoid overhead watering. Apply copper fungicide if severe.