Shrub · Ericaceae
Cranberry
Vaccinium macrocarpon
Give it acidic peat, full sun, and steady moisture, and this low creeping vine rewards you with tart fall berries.
Full sun
Every 2–4 days
USDA 3–7
4–8 in · 10–20 cm
Overview
The cranberry is a low, trailing evergreen vine native to the cool bogs and wetlands of northern North America. It belongs to the heath family alongside blueberries and lingonberries, and like its cousins it lives for very acidic, peaty ground that would starve most garden plants. The vines creep along the surface and root as they go, mounding only a few inches tall while spreading wide.
What sets a cranberry apart is how particular it is. The bed must stay evenly moist yet drained, the soil must sit near pH 4.0 to 5.5, and the plant wants full sun to fruit well. Pink and white flowers open in late spring, and the familiar red berries ripen through the fall. It is hardy and long-lived once settled, but it tests your patience before it pays you back.
This is a plant for a dedicated corner, not a mixed border. Give it a contained bog bed or a wet, acidic patch where its runners can roam, keep the lawn and vegetables well clear, and a cranberry planting can fruit for decades.
Care
The short version: full sun, constant even moisture, and acidic peaty soil around pH 4.0 to 5.5. Keep fertility low, give the runners room to spread, and rake out the excess in early spring.
Light
Cranberries fruit best in full sun, with 6 or more hours a day. They will hang on in partial shade, but a shaded bed runs to leafy runners and gives you few berries.
Water
Keep the bed in constant, even moisture, watering roughly every 2 to 4 days so it never dries out. The trick is drainage to match: the roots want damp peat, not a permanent pond, so give the water somewhere to go.
Soil
Plant in acidic, organically rich peat and sand, kept consistently moist but well-drained. Aim for a pH of 4.0 to 5.5, well below what most plants tolerate, which is exactly why cranberries need a bed of their own.
Temperature
This is a cold-hardy plant, comfortable from -40°F to 86°F (-40°C to 30°C). Hard winters are no threat; it is summer heat above that range, not cold, that pushes it past its limits.
Humidity
Average humidity around 40% to 70% suits cranberries well. Good airflow through the bed matters more than any exact number, since stagnant, damp growth is what invites fruit rot.
Feeding
Feed lightly from spring through early summer with a fertilizer made for acid-loving plants. Cranberries want low fertility, so go easy: too much nitrogen grows runners and leaves at the expense of fruit.
Pruning
Pruning is minimal. Rake or mow out the excess trailing runners in early spring to push the plant toward upright fruiting shoots and to keep air moving through the bed.
Repotting
A bog-container planting rarely needs repotting. Refresh the acidic media every 2 to 3 years, and watch for roots circling the pot or runners crowding the surface as a sign it is time.
Size & spacing
The vines stay low, just 4 to 8 inches (10 to 20 cm) tall, but they spread from 1 to 6 feet (30 to 180 cm) wide. Plan for that creep and give each plant room to mat out across the bed.
When to plant
Cranberries run on the northern seasons and suit USDA zones 3 to 7. Set rooted cuttings or vine pieces out in spring once the soil can be worked, watch for pink and white bloom in late spring, and gather the ripe red fruit from early fall.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Plant: Set rooted cuttings or vine pieces out in spring once the soil can be worked (April to May).
- Harvest: Blooms May to June with pink and white flowers; fruit ripens and is harvested September to November.
Hardiness
USDA hardiness zones: 3–7
Temperature: down to -40°C
Troubleshooting
Most cranberry trouble traces back to two things: soil that has drifted out of the acidic range, or a bed that stays too wet and stagnant. Read the early signs on the leaves and berries and you can usually correct the cause before the planting suffers. Match what you see below, then act while it still helps.
Leaves turning yellow or red between the veins
This is chlorosis, and it shows up when the soil drifts above about pH 5.5 and locks iron away from the roots. Test the bed first, then bring it back down with elemental sulfur or fresh acidic peat. Watering with non-alkaline water and feeding an acid-loving plant food keeps the color where it should be.
Fix:
- Acidify soil with elemental sulfur or amend with acidic peat
- Irrigate with non-alkaline water
- Apply a fertilizer formulated for acid-loving plants
Berries going soft, sunken, or rotten
Warm, wet, poorly drained beds invite fungal fruit rot, which leaves the berries soft and discolored. Pull and bin every infected berry, then open the bed up with better drainage and airflow. A registered fungicide is worth reaching for only when the rot runs ahead of you.
Fix:
- Improve drainage and air circulation
- Remove and discard infected fruit
- Apply a registered fungicide per label if severe
All vine and leaf, hardly any fruit
When a bed runs to dense trailing runners with few upright shoots, it is usually too much shade or too much nitrogen pushing growth the wrong way. Move it into full sun and ease off the feed. Raking or pruning the surplus runners in early spring tips the plant back toward the uprights that carry the berries.
Fix:
- Site in full sun
- Reduce nitrogen fertilization
- Rake or prune excess runners in early spring
Toxicity
Good news here: the cranberry is non-toxic from root to berry. The fruit is a kitchen staple, and the extract is even fed to cats and dogs for urinary health. The worst a hungry pet faces is a mild stomach upset from eating too many at once.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
Cranberry is safe for cats, and the berry even turns up in feline urinary supplements. A cat that gulps a pile of fruit might get a brief upset stomach, nothing more.
Dogs None
Dogs can eat cranberries without harm, and the extract is fed to them on purpose for urinary health. The only catch is a soft stool or mild gas if one helps itself to a big bowlful.
Horses Safe
The low vines and tart berries pose no danger to horses grazing nearby.
Rabbits Safe
Rabbits can nibble the foliage and fruit safely, though berries are best as an occasional treat rather than a staple.
Livestock Safe
Cattle, goats, and sheep come to no harm from cranberry plants or their fruit.
Birds Safe
Birds eat ripe cranberries freely in the wild and spread the seeds, with no risk attached.
People Safe
Cranberries are a kitchen and holiday favorite, eaten cooked, dried, or as juice. Raw berries are simply very tart, not unsafe.
No special handling needed; the plant is non-toxic, though eating large amounts of fruit may cause mild digestive upset.
Varieties
A handful of cultivars carry most of the cranberry harvest, bred for color, yield, and how well the fruit keeps. These are the names worth knowing.
Stevens
A high-yielding, disease-resistant hybrid that has become the most widely planted commercial cultivar.
Ben Lear
An early-ripening variety prized for its deep color and leaned on heavily in breeding programs.
Howes
An heirloom Massachusetts selection whose firm berries store and keep unusually well.
Companions
Plant near
Lowbush blueberry (Vaccinium angustifolium): Shares the same very acidic, peaty, moist soil and growing conditions.
Lingonberry (Vaccinium vitis-idaea): Another acid-loving evergreen groundcover with matching soil and moisture needs.
Keep apart
Lawn grasses and most vegetables: They need near-neutral soil and cannot tolerate the very acidic, wet conditions cranberries require.
How to propagate
Cranberries are nearly always started from cuttings or by layering, both of which clone a known cultivar. Seed is possible but slow and unpredictable, so few growers bother.
Stem cuttingsModerate
Spring to early summer · Roots in a few weeks; 3 to 5 years to a full fruiting bed
This is how cranberries are grown commercially. Push 6 to 10 inch vine cuttings into moist acidic peat and sand from spring through early summer and keep them consistently damp. Roots form within a few weeks, but expect 3 to 5 years before the bed fills in and fruits in earnest.
LayeringEasy
Spring to summer · One growing season to root
Cranberries layer themselves with no help from you. Trailing runners root wherever they touch moist soil, so pin a runner down in spring or summer and it will anchor over a single growing season into a new plant.
SeedDemanding
After cold stratification in late winter · Several years
Seed is rarely worth the trouble. The seed needs cold stratification in late winter to sprout, the seedlings crawl along for several years, and they don't come true to the parent cultivar.
Myths
Cranberries grow underwater in flooded bogs.
Cranberries grow on low trailing vines in moist, well-drained acidic peat, not under water. Growers flood the beds only briefly, for wet harvest and winter protection. During the growing season the soil is kept drained, never submerged.
Cranberry berries are toxic to dogs and cats.
Plain cranberries are non-toxic to pets, and the extract is even sold in pet urinary supplements. Only a large helping might cause mild stomach upset, which is true of almost any fruit.