I would say the top-selling shrub at the nursery in the last two years has to be the blueberry. It is great to see people getting back to growing their own food. To be successful at growing blueberries you must understand a few of the plant’s crucial cultural requirements.
To grow blueberries successfully you need three things: acid soil, good drainage and adequate soil moisture.
First they require acidic soil with a pH range between 4.0 – 5.0. Unfortunately most of our soil is alkaline with pH readings of above 7. I strongly recommend purchasing an inexpensive soil testing kit. You will be able to test for pH, nitrogen, phosphorus and potassium. Changing the pH of the soil takes time and you need to test the soil every year to see where your soil is at.
Adding granular sulfur and peat moss and organic matter such as compost to the soil at planting time is a must. Make sure the sulfur is well mixed into the top 10 cm of the soil. Adding sulfur is not a one-time deal it must be added every year to maintain fertility and acidity. Apply aluminum sulfate yearly as per directions, keeping the fertilizer at least 15 cm away from the plant.
I would recommend using a fertilizer specific to evergreens or rhododendrons throughout the growing season as this is specific to acid-loving plants. Miracid is a water soluble type that is available quickly to the plant.
Blueberries hate wet feet; they are not a bog plant.
If your planting site is not in well-drained soil you must make a raised bed up to 45 cm high and 90 cm wide for proper drainage. They will develop root rot in saturated soils.
You must also be aware that blueberries have a very shallow root system. They need at least 2.5 – 5 cm of water weekly. During dry periods extra watering is necessary especially to produce fruit. A generous 10 cm mulching using bark mulch or peat moss will help control weeds, conserve moisture and keep roots cool. As the mulch decomposes over the year it will also help improve the soil structure.
Blueberry plants will not require pruning for the first three years. Prune in early spring by first removing any dead or diseased branches. Remove interior crossing branches to improve air and light circulation.
Flower buds are produced on tips and down the branches of second year old shoots. As these branches grow older they are less productive and should be gradually pruned out to encourage new branches to form. Highest yields are formed on two- to four-year-old branches.
Highbush blueberries are self-fertile, but produce better crops with two varieties for cross pollination and to extend the picking season. They can be planted 1.2 m apart but can be planted closer .6 to 9 m apart if using them as a small hedge. They are also ornamental with their lovely red fall colour.
Jean Atkinson is a horticulturist with Richbar Golf and Garden and a regular Observer columnist.