Cranberries are not hard to grow. They do require cool temperatures, acidic soil, and plenty of water.
The cranberry is a low, creeping, evergreen shrub, almost a vine. It has a woody stem that runs along the ground. Stems can grow 6 or 8 feet long. Upright shoots grow from the stems. Berries form at the top of the shoots from pink flowers.
Cranberry fruit is small and tart. The ripe fruit is deep red.
The high acidity of the cranberry makes it excellent for relishes and jellies. Cranberries will add zest to salads, stuffings, cakes, muffins, pies, and puddings. Cranberry juice is refreshing and can be used in punches and cocktails.
Best Climate and Site for Growing Cranberries
- Cranberries grow best in USDA Zones 4 to 7. Cranberries require three months of chilly winter weather at 32°to 45°F to ensure flower set and fruiting in spring.
- Plant cranberries in full sun but not in a location that gets too hot; a south-facing location is not optimal.
- Cranberries thrive in moist, well-drained, humus-rich soil. They are often grown on sandy or peaty bogland. Cranberries can grow in ordinary acid soil. Planted in ordinary soil use a heavy peat mulch to protect plants in winter.
- Cranberries grow best in acid soil; a soil pH of 4.0 to 5.5 is optimal.
- Grow cranberries on a raised bed or in a sunken bed where you can control the acidity of the soil and drainage.
- Plants do not tolerate dry soil, but they can withstand flooding in cold weather.
- Flowers are self-pollinating; honeybees will increase the size of the crop.
- Cranberries grow to 1 foot high and wide or slightly larger. The stems root where they touch the ground and continue to grow larger.
- Space cranberries 1 to 2 feet apart.
- Plant cranberries in autumn where winters are mild. Plant cranberries in spring where winter is cold; plant after all danger of frost has passed. Avoid planting cranberries in hot, dry weather.
- Prepare the planting bed by mixing shovelfuls of acid peat into the soil before planting.
- You can make a special bed for cranberries; set an old bathtub or animal watering trough in the ground or line a sunken bed with ceramic tile then fill with acidic potting mix.
- Dig a hole half again as deep as the root ball and twice as wide; moisten the hole before planting.
- Plant cranberries so that the soil mark of the nursery pot is level with soil of the new planting hole.
- Backfill the hole with half native soil and half aged compost or commercial organic planting mix. Firm in the soil to be sure no air pockets remain around the roots.
- Water the new plant in with a high phosphorus liquid starter fertilizer.
- Keep the soil evenly moist as the plant begins to grow.
- Cranberry planting beds are not covered with water; this is a popular misconception.
Container Growing Cranberries
Grow cranberries in a container that is at least 12 to 18 inches deep and wide or wider. Here are two methods:
- Fill the container with acidic potting mix and coarse, lime-free grit to improve drainage; place the pot in a saucer topped off with water so the soil never dries out then plant.
- Construct a bed of perforated plastic (use pre-formed rectangular plastic pond). Fill the bed with acidic potting mix or low pH soil; cover the surface with a layer of lime-free grit or sand to act as a mulch then plant; established plants will spread to form a mat-like ground cover.
Cranberry Care, Nutrients, and Water
- Cranberries require a lot of water; keep the soil constantly moist. Cranberries root into only the top 6 inches of soil which must be kept moist.
- Cranberries do not require regular feeding; apply a lime-free, liquid general fertilizer in mid-spring.
- A topdressing of grit or sand across the planting bed will help retain moisture and keep down weeds.
- Keep the soil weed-free until shoots create a thick mat covering the soil.
- Renew the mulch or grit or sand periodically; you can also mulch with sawdust.
- Prune or trim cranberries in spring to keep them bushy; removing runners will keep plants compact and bushy.
- Prune cranberries so that they do not become overcrowded. Prune by cutting away some of the sprawling stems and some of the upright fruiting stems. Prune so that the remaining stems have room to grow on.
- Cranberries are commonly propagated by stem cuttings which root readily.
- Take cuttings from upright shoots in spring before terminal buds begin to sprout.
- Set cuttings on 18-inch centers in peaty soil with an inch of cutting above the ground.
- Where winters are mild, set rooted cutting outdoors in fall or set them out in early spring.
Harvesting and Storing Cranberries
- Cranberries are ready for harvest when they are fully colored, deep red, usually in autumn. Berries that are pink or white are not ripe.
- Cranberries are usually harvested by hand or mechanical harvester. Commercial growers flood the field to cover the plants by 6 to 8 inches of water. Berries float to the surface for collection. In the home garden, the planting bed does not need to be flooded.
- Ripe berries can stay on the bush for a month or two as long as there is no freezing weather; pick cranberries as you need them.
- Frost will damage the berries so harvest before freezing temperatures.
- Berries are too tart to eat raw; add sugar and use in juices, jellies, muffins, and cranberry sauce.
- Cranberries will keep in the refrigerator for two to three months in an airtight plastic bag or container; they also can be frozen.
Cranberry Problems and Control
- Yellowing leaves is a sign of chlorosis; it can be lime-induced; leaves yellow at the edges and yellowing spreads between the veins which remain green; apply chelated iron.
- Fruitworms bore into fruits, eats the seeds and exit; fruitworms are the larvae of a Sparganothis moth; use pheromone lures to trap moths.
- Spotted fireworm is the larvae of a moth; fireworms eat fruit; control adults with pheromone lures to traps.
Cranberry Varieties to Grow
There are more than 100 different cranberry cultivars that grow in North America. Traditional varieties include: ‘Early Blacks’, ‘Howes’, ‘Stevens’, ‘Searles’, ‘Ben Lear’, ‘McFarlain’. Other cultivars include: ‘Crimson Queen’, ‘Mullica Queen’, ‘Demoranville’, Other varieties of cranberry available from the Grygleski family include: ‘GH1’, ‘BG’, ‘Pilgrim King’, ‘Valley King’, ‘Midnight Eight’, ‘Crimson King’, ‘Granite Red’.
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