Cranberry
Vaccinium macrocarpon
Low-growing evergreen groundcover requiring acidic, consistently moist soil. Can be grown in containers with an ericaceous compost mix.
Overview
Companion Planting
Good Companions
BlueberryBad Companions
None
Toxicity
Cranberries are non-toxic to humans, dogs, and cats (ASPCA-listed as safe). Feed pets only plain berries in moderation, as sweetened or dried products may cause digestive upset.
Planting Tips
1 cm of water per m² equals 10 liters. Use the Watering Calculator for exact amounts.
Care Tip: Top-dress beds with a 1-2 cm layer of coarse sand every 2-3 years to encourage new upright growth and suppress weeds. Prune runners that escape the bed.
Common Pests
Cranberry Fruitworm (Acrobasis vaccinii)
Symptoms: Larvae bore into developing berries, which turn red prematurely and are webbed together with silk.
Treatment: Apply Bacillus thuringiensis (Bt) or spinosad at early bloom when larvae are small. Remove and destroy infested fruit clusters.
Prevention: Monitor with pheromone traps from late bloom onward; flood beds briefly in spring to drown overwintering pupae.
Spotted Fireworm (Sparganothis sulfureana)
Symptoms: Larvae web together leaves and shoot tips, skeletonize foliage, and may feed on developing fruit.
Treatment: Apply Bt or spinosad when young larvae are first observed. Hand-pick webbed leaf shelters in small plantings.
Prevention: Scout for egg masses on leaf undersides in late spring; maintain good air circulation by sanding and thinning runners.
Cranberry Weevil (Anthonomus musculus)
Symptoms: Adults puncture flower buds to feed and lay eggs; infested buds fail to open and drop prematurely, reducing fruit set.
Treatment: Apply pyrethrin-based sprays at bud swell if monitoring shows threshold numbers. Remove dropped buds from the bed.
Prevention: Use sweep-net sampling in spring to detect adults early; flooding beds in late spring can reduce populations.
Common Diseases
Fruit Rot Complex (Colletotrichum, Physalospora, Coleophoma spp.)
Symptoms: Berries soften, discolor, and decay on the vine or in storage; affected fruit may appear water-soaked or develop dark lesions.
Treatment: Apply copper-based or chlorothalonil fungicide sprays at early bloom and repeat at mid-bloom. Remove and discard infected fruit promptly.
Prevention: Ensure good air circulation by sanding beds regularly; avoid excessive nitrogen fertilization; harvest promptly when ripe.
Upright Dieback (Phomopsis vaccinii)
Symptoms: Individual uprights wilt, turn brown from the tip downward, and die; lesions may appear at the base of affected shoots.
Treatment: Prune and destroy affected uprights well below visible symptoms. Apply fungicide (e.g., copper or mancozeb) during active growth if severe.
Prevention: Sand beds every 2-3 years to promote healthy new growth; avoid overhead irrigation during warm, humid weather.
Fairy Ring (Strasseria geniculata / various fungi)
Symptoms: Circular rings of dead or stunted uprights appear in the bed, expanding outward each year; mushrooms may fruit along the ring edge.
Treatment: No effective chemical control exists. Remove and replace soil and vines in affected rings with fresh peat-sand mix and new cuttings.
Prevention: Maintain vigorous vine growth through proper sanding and fertilization; avoid waterlogged conditions during dormancy.