Along with figs, this year I am trying my hand at Blueberries. I currently have seven varieties, six in containers.

Blueberries 

Blueberries can be a little trickier than some fruits to grow. They have specific soil and nutrition needs and for decent crops need to be cross pollinated. Blueberries are often advertised as self-fertile, however cross pollination with another blueberry of the same type will greatly increase both yield and berry size. Blueberries also require a number of chill hours in order to set fruit.

However it is important that you choose blueberry plants from the same type, as not all blueberry plants will cross-pollinate with each other.

Soil selection

Blueberries are quite particular in their soil needs. They enjoy an acidic soil with a pH between 4.5-6.

Blueberries over time have adapted to lower pH environments, which today means that they will suffer mineral deficiencies in higher pH soils. In particular blueberries will suffer from an iron deficiency as their ability to absorb iron decreases with higher pH. Iron deficiency in blueberries is marked by chloriotic (yellowing), leaves.

Blueberries also require a free draining soil, free from weed competition. Blueberry root systems are very shallow.

Nutritional Needs

Blueberries have a different root system to the majority of plants. Normally, plants will form roots, and then fine feeder hairs, to collect nutrients. Blueberries lack these fine hair-like roots, and instead, form a symbiotic relationship with mycorrhizal fungi.

Blueberries are somewhat different from other plants in their nitrogen needs. Nitrogen (N) is an essential element that promotes leafy growth in plants, and in most fertilisers exists in a nitrate form. In chemistry nitrates have a chemical composition of NO3. Blueberries, and some other acid loving plants, prefer to receive nitrogen in an ammonia form, which has a chemical composition of NH4. Because of this, it is important when choosing a fertiliser for blueberries that you select one with an ammonia based nitrogen source. Generally, this can be found in acid-loving fertiliser mixes.

Below is a picture on the difference in blueberry root development when fed with a nitrate (NO3) vs ammonia (NH4) based fertiliser. The source of this picture, and lots of additional fertilising information can be found in this paper.




Blueberry Types

Blueberries come in three common types, blueberries will cross-pollinate with other plants within the same type, although some studies have shown limited cross pollination with blueberries of another type, in particular Southern Highbush and Rabbiteye types. To be safe, plant at least two varieties of the same type together.

Highbush

Highbush blueberries are so named because of their taller stature, sometimes growing up to 3m tall. Highbush types have a high chilling hour requirement, needing at least 1000 hours under 2oC to satisfy their dormancy requirements. These plants are quite hardy and frost tolerant. Highbush types are also able to tolerate high summer temperatures, making them great for cooler Australian climates.

This year, I have planted two varieties of Highbush blueberries

Blue Rose




Denise




Edit, on 30 March I added two new Highbush blueberries to the collection; Brigitta an Blue Crop



Southern Highbush

Southern Highbush types have lower chill hour requirements than Highbush types, needing between 250-600 hours of chill. Southern Highbush types do not have the frost tolerance of Highbush types and must be protected in areas like Canberra. Southern Highbush types have a tolerance for heat.

In Australia Southern Highbush varieties account for up to 80% of total blueberry production, due to the extended growing season.

Growing Southern Highbush types in Canberra can be troublesome due to our cold winters. Blueberries are perennials, meaning they live for many years, and in cold areas will die back each spring as cold weather approaches, to re-grow in Spring. Blueberries in containers should be moved to a warmer location to over-winter, and Southern Blueberries in the ground need extra frost protection if they are to survive.

This year, I have three Southern Highbush varieties

Legacy



Sunshine Blue




Misty




Rabbiteye

Rabbiteye blueberries are so-called due to their appearance when ripening looking (unsurprisingly) like the eye of a rabbit when the berries are in their pink stage. Rabbiteye varieties often have larger fruits, with thinner skins. Rabbiteye varieties can grow as large as, or even larger than Highbush types. Rabbiteye varieties have the ability to far out-live other types, growing for as long as 20 years or more.

Rabbiteye blueberries are low-chill varieties and need between 450-600 chill hours. Rabbiteye blueberries flower before Highbush types, and the flowers are very susceptible to spring frosts, and containerised plants should be moved to warmer locations if frost is predicted in spring. In Canberra, as the saying goes, you aren't (relatively) safe from frosts until Melbourne cup day, although late frosts into November or even December can occur.

This year, I have two Rabbiteye varieties;

Powderblue





Brightwell