BattenBlooms
PL. —Dahlia coccinea, 'Bishop of Llandaff'Botanical illustration — drop image
Dahlia coccinea, 'Bishop of Llandaff'

Bishop of Llandaff Dahlia

SummerFall
8a–11bHardiness zone
Peak bloom windowZone 6b · frost-offset weeks
Winter
Not in bloom
Spring
Not in bloom
Summer
Not in bloom
Fall
Peak bloom
Peak bloom
In bloom
Background

The 'Bishop of Llandaff' is a beloved heritage dahlia prized for its striking contrast of scarlet-red, semi-double flowers set against dramatic dark, bronze-purple foliage. Introduced in the 1920s, it remains a garden favorite for adding bold color and architectural interest to borders and cutting gardens.

Though tender, the tubers can be lifted and stored over winter in colder climates and replanted after the last frost. It attracts pollinators throughout the late summer and into fall, making it both ornamental and ecologically valuable.

Good companions
Achillea millefoliumCalendula officinalisTagetes patulaZinnia elegans
Care guide
SunFull sun, at least 6-8 hours of direct light per day for the best flowering and richest foliage color.
WaterKeep soil consistently moist during the growing season; water deeply once or twice a week and avoid waterlogging the tubers.
SoilRich, well-drained soil amended with compost; slightly acidic to neutral pH works best.
SpacingSpace plants 18-24 inches apart to allow good airflow and room for the bushy growth.
Height36-48 inches tall, often benefiting from staking to support the abundant blooms.
Zone8a – 11b
Seasonal tasks
spring
sowStart tubers indoors or plant out after the last frost once the soil has warmed.
summer
watchMonitor for slugs and earwigs, which are drawn to the tender new growth and dark foliage.
cutHarvest blooms regularly and deadhead spent flowers to encourage continuous flowering.
fall
watchLift and store tubers in a frost-free location before the first hard freeze.
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.

Tuber Rot

Symptoms

Stored or in-ground tubers turn soft, brown, and mushy, often with mold growth. Affected tubers fail to sprout in spring.

Treatment

Lift tubers only after foliage dies back, cure them in a dry airy spot before storage, and store in a cool dry location with breathable packing. Discard damaged or soft tubers and avoid waterlogged soil during the growing season.

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.

Aphids

Symptoms

Clusters of small soft insects on new growth and flower buds.

Treatment

Knock off with a strong jet of water. Ladybirds and lacewings are natural predators. Insecticidal soap as last resort.

Spider Mites

Symptoms

Fine stippling or bronzing on leaves, faint webbing on undersides, foliage drying out during hot, dry weather.

Treatment

Spray foliage with a strong jet of water to dislodge mites. Apply insecticidal soap or horticultural oil to leaf undersides; repeat every 5–7 days as needed.

Crown Rot

Symptoms

Lower leaves yellow and wilt; the base of the rosette turns brown and soft, sometimes with white fungal threads at the soil line. Plants collapse in wet conditions.

Treatment

Remove and destroy affected plants. Improve drainage and avoid overhead watering. Do not mulch directly against the crown. Space plants for airflow and avoid replanting in the same wet spot.