All About Cranberries

The humble cranberry is an interesting little fruit in its own right. Found all around the cooler parts of the Northern Hemisphere, it’s become part of a great many dishes and cuisines over the years. With an iconic red color and tart flavor, cranberries are a versatile ingredient and a beloved holiday food. So whether you’re celebrating Canadian Thanksgiving, US Thanksgiving, Christmas, or just the winter holiday season, cranberries likely appear on your table at this time of the year. We all know the flavor, but how much do you know about the science and history of this plant? Let’s dig in and learn all about cranberries!

Three Species, One Name: What are Cranberries, Exactly?

What a cranberry is, exactly, will depend on where in the world you are. The word “cranberry” generally refers to one of three closely related species of low-growing, creeping shrubs found in acidic bogs in the temperate or sub-arctic regions of the Northern Hemisphere:

· Vaccinium oxycoccos or the common cranberry is the most widespread species, found all around the cooler regions of Asia, Europe, and North America.  It’s definitely a cool/cold climate plant, with smaller leaves, small dark pink or red flowers, and a small pink or red berry. The fruit have a tart, acidic flavor often described as “refreshing” or “invigorating” and are used as a food item throughout its wide native range.

· Vaccinium microcarpum or the small cranberry is more restricted in its range than V. oxycoccos, but it’s still found over an impressively wide territory in the northern parts of North America, northern Europe, and northern Asia. It’s similar to V. oxycoccos, but it has smaller flowers and leaves with smaller, hairless stems. It’s not as commonly used as a commercial foodstuff as its relatives V. oxycoccos or V. macrocarpum, but you may find it in local markets or in regional dishes within its native range.

· Vaccinium macrocarpum, also known as the large cranberry or American cranberry is the star of the show at many a holiday meal in the eastern parts of the US and Canada, which comprise its native range. Found natively as far south as the mountains of North Carolina, it features large foliage and larger, more numerous flowers than V. microcarpum, with tasty berries that have a flavor similar to tart, acidic apples. It’s commonly grown as a commercial crop throughout its range.

Culinary enthusiasts often seek out different varietals of cranberry for their different flavors, but in most North American grocery stories you’re mostly likely to encounter V. macrocarpum varietals like “Crimson Queen” and “Mullican Queen”, which have been bred for both flavor and productivity. If you get a chance to try wild cranberries or more historical varietals, do it! They offer a rich palate of flavors and are a great way to connect with our agricultural and culinary past.

But back to the present—how are cranberries produced now? Let’s dig a little further . . .

From Bog to Table: How Cranberries are Grown

Cranberries of all species commonly grown in wetter soil or in wetlands, and that natural trend informs their commercial cultivation. Traditional cranberry beds were planted in either naturally occurring wetlands or in human-constructed “cranberry bogs”, and that tradition continues today. Commercial cranberry beds are most often built in areas with a shallow water table. We’re used to talking about raised bed gardening, but this is a form of recessed bed gardening: the beds are either dug into the ground or surrounded by raised dykes so that they can be flooded during harvest season. While the beds are irrigated/watered and fertilized throughout the year to help the plants grow, the “bogs” are only filled with water for harvest time. This flooding does two things: it makes harvesting easier and helps protect the plants in cooler weather. The ripe berries float on the surface, making them easy to corral and harvest, while the mass of the water acts as a heat sink and helps protect the plants from the cold.

The end result is rather beautiful—flooded beds covered with a bright red or dark pink blanket of cranberries. If you get a chance to see this unique approach to agriculture in person, we promise it’s worth it. And fresh cranberries have a flavor that’s difficult to match, although most folks shy away from eating them raw. You may get lucky and find a grower producing a less commonly grown species or varietal of cranberry, and if so we hope you’ll take the chance to support this kind of local, historic agriculture.

Can We Grow Cranberries at Home?

We know our readers, and we know many of you are wondering: can I grow cranberries in my home garden? The answer is: maybe! If your climate is clement to cranberries, you can absolutely grow some at home! Warm and hot climate gardeners may find this a lot more challenging or even prohibitive, however, so as always we recommending checking with your local extension office or gardening club for location-specific advice.  Most home cranberry gardeners start by purchasing young plants or rooted cuttings rather than starting from seed, and many home growers prefer older varietals like “Howes”, “Ben Lear” or “Early Black”, although hybrids like “Stevens” are also popular.

Cranberries need a bit of space—our primary research source recommends a 50 square foot/4.6 square meter plot for six cranberry plants. Space plants about 24 inches/50 cm apart for best results. Cranberries do best with a looser sandy soil rich in nutrition and generally kept damp, so you can loosen your soil with peat moss if needed and add water slowly. A relatively balanced fertilizer (2-4-2) in liquid form works best, but you can sue compost if you add gradually and consistently throughout the season. Cranberries can be grown in containers, but plan on a relatively large one—10 gallons or so—per plant and a lot of watering to keep them damp.

Cranberries are generally ready to harvest in late autumn, late September to late October depending on location. Flooding isn’t necessary for most home gardens. Harvest by hand when the berries are a mature red or dark pink in color, again depending on varietal. These plants can be quite prolific, with the 50 square foot/4-5 square meter bed we outlined above producing up to 10lbs/4.5kg once established, generally in the third or fourth year of growth.

Cranberries: A Classic Fruit, A Rich History

We learned a lot in writing and researching this blog, and the experts we spoke with confirmed what we had long suspected: there’s something special about cranberries. They have a history that spans continents, a special place in many cuisines, and a wide palate of flavors depending on location and species/varietal. We’d love to hear from anyone who has experience growing them, so if you have cranberries on your farm or in your home garden please reach out. For everyone else, we hope this blog entry helps you better enjoy and appreciate the cranberries on your table this holiday season and maybe encourages you to try growing some of your own!