All About Blueberries

Blueberries have recently supplanted strawberries as Canada’s most popular berry. Much of this is due to their ease of use; no hulling required. Their flavour is nearly always good and they remain useable for extended periods. They do not seriously deteriorate when frozen and thawed. And there has been considerable buzz about them being an excellent source of antioxidants.

Historical Development
 

Being a native North American crop, blueberries have been widely used by First Nations people for centuries. The small berries were harvested from low-growing naturalized wild plants in forested areas. Varieties have naturally adapted to the various climates of the Far North of Eastern Canada down to the southern areas of the Eastern United States.

It was only in the early 1900s with the development of easier-to-harvest, taller “high-bush” plants with larger berries that blueberries became a commercial crop. By the 1930s they had begun appearing in markets around the world. Since they have very special requirements for highly acidic soil, they were not a common home-garden plant.

With the advent of harvesting machines that shake ripe berries off the plants, the prices came down and these berries became more popular. Breeding to shorten their winter chilling requirement has expanded the range where blueberries can be grown. As a result, the season for fresh berries has been considerably extended.

The more recent adoption of harvest-shakers for small, low-growing “wild” blueberries has supported the rapid expansion of an affordable commercial market for smaller berries. Most of these are individually quick frozen (IQF) for export around the world.

The term “wild blueberries” might infer their being pesticide-free and forest-harvested with traditional hand-held blueberry rakes. In actual fact, about 80 percent of Canada’s “wild” blueberries are harvested by machine on agriculturally managed blueberry barrens. These fields are periodically mowed or burned to reduce completion from trees and shrubs. They are fertilized to boost production and sprayed with pesticides to minimize insect and fungus damage. But the bushes do naturally plant themselves.

Nutrition
 

Blueberries are not a great source of nutrients. They do have a reasonable amount of Vitamin C, are a good source of dietary fibre and a very good source of phytonutrients (antioxidants such as polyphenols, anthocyanins, and flavonoids that promote good health). These are unusually stable even after being frozen; but they are broken down by cooking.

Purchasing Blueberries
 

Choose blueberries with a uniform dark blue colour with a light gray “bloom.” An easy way to determine if the berries are fresh is to shake the container. If they make some noise, they are appropriately firm. If there is no sound, the berries are too soft and over-ripe. A bag of frozen berries with a big clump has likely been thawed somewhere in the distribution system; choose one in which the berries still flow. Do not wash your berries until just prior to use.

Quality Growing
 

Growing blueberries is a long-term project but they will continue to provide delicious seasonal fruits for many years to come. They require very different conditions from most other garden crops. They insist upon very acid (low-pH) soil with low fertility and very high organic matter. They also require regular watering, along with excellent drainage. This means that the common heavy-clay, high pH, fertile, poorly drained soils in Southern Ontario are clearly not suitable.

The best solution is to grow blueberries in large (24-inch diameter and about 18-inch deep) pots. Fill this with a blend of 50 percent coarse peat moss, 20 percent coarse sand, 15 percent compost, and 15 percent topsoil. For each container, mix in 50 grams of powdered or pelleted elemental sulphur (to lower the pH below 5.0). If you still want to grow blueberries in your garden, dig out somewhat larger holes than the pots, then fill these with this same mixture. It is best to prepare the soil a year ahead of transplanting in your plants.

Purchase 2- or 3-year-old blueberry plants from a reputable local nursery. For a longer harvest period, select varieties with differing harvest dates. For improved yields, select two different varieties for each harvest period. For lower plants with smaller berries, choose the low-bush form and plant them 1½ inches below the surface so they will be encouraged to spread. For taller plants with larger berries, choose the high-bush form and plant them to the same depth you got them in. A useful new compromise is the new half-high bush form.

For the first two years, water regularly and prune off the flowers to promote plant growth. Spread a thick (3-inch) layer of mulch around the plants to hold back grass and weeds and to retain moisture for the shallow roots. After the third year, prune any thin stems but no longer prune the flowers, which will start producing fruits. Cut away any stems that become larger than one-inch thick. If you are growing the plants in pots to keep on a patio, dig a hole in the garden in which to store the pot completely buried (to the plant’s soil level) to protect the roots through the winter.

Blueberries do not have many pests other than birds, which love the ripening berries. You may need to cover the plants with a net during the harvest season. Soil tests are the best way to know that the soil’s pH remains below 5.0. Add more sulphur to the surface if it needs to be lowered.

For the best flavour, harvest the berries about five days after they turn completely blue. I find the best way to do this is to shake the clusters into a container. The perfectly ripe berries simply fall off. Repeat every two or three days.

Uses for Blueberries
 

There are so many familiar sweet uses for cooked blueberries—muffins, crisps, waffles, pies, jams, jellies and, of course, pancakes. Knowing that raw or frozen blueberries retain their phytonutrients, use them in smoothies, green salads, carrot salad, cold or hot cereals, layered with creamy yogurt or kefir, or stirred into fresh salsas.

Special combinations that I like:

Pizza: Scatter blueberries as a garnish over your favourite homemade (or frozen) pie.

Crostini: Layer slices of barbecued melon over crisped bread and garnish with blueberries.

Gazpacho: Finely chop or coarsely blend blueberries with sweet pepper, cucumber, sweet onion, and lime juice.

Baked Acorn Squash: Remove the seeds from each half of the squash. Cook the squash halves cut-side up on a raised shelf in a covered barbecue or grill with a branch of smoking rosemary on the grill, or bake at 325° F, until the flesh is soft. Then fill the cavities with a mixture of seasoned cooked quinoa and plump blueberries.