March COASTSIDE / Growing Things

Fast-forward 50 years and, although Carlin argued that blueberries were actually purple, it turns out he might have been onto something. The “blue” in blueberries comes from a group of phytochemicals called anthocyanins, powerful antioxidants that may help your body defend itself against a long list of diseases. Eating blueberries is not likely to make you immortal, but there is no doubt that they are highly nutritious and, as such, are commonly touted as a “superfood.” 

In addition to being delicious, blueberries are easy to grow and make attractive additions to the home garden with profuse clusters of white or pink blossoms in early spring and colorful foliage in the fall. Since nothing is healthier or more delicious than fresh-picked blueberries, here’s how you can grow your very own “superfood.” 

Pick the right variety

Blueberries are traditionally associated with colder parts of the country where a particular number of “chill hours” are required for higher volume fruit production. (Chill hours are defined as hours with temperatures less than 45°F but above 32°F.) In recent years, several blueberry varieties have been developed to produce adequate amounts of fruit without extended periods of “chill” temperatures.

Look for plants with low chill requirements listed on the label — 300 hours or less. If even that sounds like a lot for our mild coastal winters, don’t be dismayed. You may not produce bushels of blueberries for the farmers market, but you’ll still have plenty. 

Blueberry plants that do well in the mild winter conditions of our coastal areas include Southern Highbush, a hybrid of native Highbush and Southern Lowbush Blueberry varieties. These cultivars are also known for producing lots of sweet, flavorful berries. Other variations on Southern Highbush blueberries include Reka, O'Neal, Gulf Coast, Jubilee, Misty, Georgia Gem, and Marimba.

When and where to plant

Blueberries can be planted in the fall through early spring. Pick a location that receives full sun for at least six hours a day and in an area where the drainage is good. Importantly, blueberry roots need to be constantly moist and will need to be watered deeply at least once per week so convenient access to irrigation is key. Using a drip irrigation system designed to deliver water below the soil surface will be beneficial and help to conserve water. Since it might be difficult to meet all of those conditions in your garden, blueberries will also do well in pots or containers such as half wine barrels. This is also good news for space-constrained gardeners! 

Success depends on soil

Like almost all plants, blueberries thrive in soil that is rich in organic matter, but, in addition, they are acid-loving plants. You will very likely need to amend the soil in the areas where you intend to plant your blueberries in order to lower the pH to a range between 4.0 and 6.0. (Easy to use test kits are available at most nurseries.) Incorporating fibrous materials such as peat moss, coconut coir, pine needles, rice hulls and/or leaf mold will help to acidify the soil and help to retain moisture. Adding sulfur will also help to lower the pH. When you are ready to plant, a good rule of thumb is to combine roughly equal parts soil and premoistened peat moss, etc., and use that mix to fill in and around the planting area of each plant. 

What to expect

Blueberry plants in our climate normally start to bloom in mid- to late January and continue through March. Berries will form and be ready to harvest in late May and continue through September. (Tip: Resist the temptation to pick your blueberries as soon as they turn blue because they will be tart. Wait another week or two and you will be rewarded with bigger, darker colored berries with sweeter, juicier flavor.) 

Unless you want to share your blueberry harvest with the local bird population, you may want to protect your harvest with bird netting. (Note: Netting is a bit pesky and it won’t deter squirrels!) Install the netting just as the first green berries show a blush of violet. Once berry production slows down and your main harvest is done, you can remove the netting and allow your feathered friends to enjoy what’s left of the berries. They will return the favor by removing any lurking caterpillars. After several years, you may see that your original plants have sent out rhizome shoots and multiplied the number of fruit-producing stems in the garden bed. 

Care and feeding 

Blueberries should be pruned lightly every year as soon as harvest is finished to control shape and height as well as to ensure fruit production for the following year. Clean out dead or diseased wood and remove a few twigs at the bottom to create space for easier weeding and mulching. Fertilize after pruning with an acid loving flowering plant formula, usually a product with a label that claims to be optimized for azaleas. Regular applications of sulfur during periods of wet weather will help to maintain acid levels in the soil.  coastside

 Bruce Goren is a master gardener who has developed his own tomato variety, San Francisco Sunrise. Bruce is also doing experimental grafting to see if fruit trees can produce subtropical fruits in chilly San Francisco. You can find more about his work, read his comments and see his photography on Instagram at IG-@SFfruitGardener. This article was edited by University of California Master Gardeners Maggie Mah and Cynthia Nations.