I have to admit that I was surprised by the amount of phone calls generated from the mention of blueberries in my last column.
Yes, you can grow blueberries here, and they are extremely well suited to life in a container. You will definitely want to use a “low chill” variety, and just because a plant is low chill, does not mean it is automatically suited for our soil. That is where the container comes in.
In order to have a soil that the plants grow and produce well in, it needs to be acidic. I think many times we don’t appreciate just how important it is that a plant have the proper Ph for the soil it is growing in.
When you fill a container with potting soil, most have a Ph that is very suitable. The higher content of peat moss in the blend, the lower the Ph will be. Peat moss, by itself, wouldn’t be a suitable medium, but mixed with compost and soil, as it is in potting soil, makes a perfect blend. Good potting soil brands to use for blueberries are Monrovia Custom Soil Blend, Black Gold All Purpose Potting Soil or Fox Farm Planting Mix.
The best varieties to use in Tucson – those that have the lowest chill requirements – are Sharpblue, Sunshine Blue and Southmoon. These three have lowest requirements and can be used anywhere in town. For those in the lower, wash areas and cooler spots like Benson, Sierra Vista, Oracle, etc., you can also use O’neal, Misty, Jubilee and Sharpblue. All of these varieties set very heavy crops and are self fruitful. Blueberries need at least 6 hours of sun and can handle full sun as long as they are well watered.
The shrubs will be semi deciduous or in the colder areas, totally deciduous and should be pruned during the winter, the same time as roses. Pruning consists of removing twiggy growth, opening the center to allow sunlight into the crown, and shaping the plant to keep it in a rounded form. You can keep them 3- to 4-feet high and wide in a 20-inch or larger container for their entire life.
They should be fertilized weekly from mid-February through Labor Day with a water soluble fertilizer with vinegar or a commercial acidifying additive included in the regimen. Even though the potting soil that you start with is beautifully acidic, our water is alkaline and will change the Ph of the soil over time. Coffee grounds are a wonderful natural source of acidity and adding small amounts, 1/4 cup every other week, as a top dressing will be beneficial.
The easiest part of growing blueberries is harvesting! When the berries are a beautiful deep blue color and pull from the shrub easily – it is time for the first taste test. The berries ripen rapidly over the whole shrub, so generally you will harvest the majority of the berries in a three-week period.
Cathy Bishop, co-owner of Mesquite Valley Growers Nursery, has more than 30 years of gardening experience. E-mail her at firstname.lastname@example.org.