Growing blueberries in Southern California

Growing blueberries in Southern California

My wife is from Oregon, where blueberries can really grow. On our visits up there I’ve seen what healthy blueberry bushes are supposed to look like. Mine don’t look like those. But my blueberries do look better and produce more now than they did when I started trying them out about seven years back. I have learned a couple things about growing blueberries in Southern California that I think are worth sharing.

Soil pH

As you’ll read any time you read anything about blueberries, they need soil with a low pH, around 5 according to this University of California publication. We don’t have such soil in Southern California. In the two different gardens I’ve tested my unadulterated soil, they have registered about 7. (I tested with a Luster Leaf Rapitest pH Soil Tester.)

So the easiest, surest, smartest way around that is to grow your blueberries in a pot with a purchased soil mix that is already in its preferred pH range. I’ve got a friend who grows wonderful blueberries in a half wine-barrel.

I, on the other hand, have always gone the hard way and grown them in the ground and tried to alter the pH of the good old earth around the root zone of my blueberry plants. Some say this isn’t even possible. I’ve heard many people say blueberries won’t do well long-term in Southern California in the ground. My oldest plant has been in the ground for seven years and it looks as good today as it ever has. No doubt though, I’ve done numerous things to try to get the soil right. That’s a constant battle.

When I planted them I mixed peat moss into the planting hole. I’ve continuously added acidic items to the soil surface: oak leaves, pine needles, coffee grounds, and lots of extra rainwater (which has a lower pH than the imported tap water of Southern California — about 5.6 compared to about 8.4 for my particular water district).

Yet my plants still began to show chlorosis (leaves with yellowing between the veins). It’s said to be due to a deficiency of iron when the soil’s high pH doesn’t allow for the root’s intake of iron. So I bought a box of soil sulfur, but nothing much improved. Then I bought a box of aluminum sulfate and incorporated some of it into the soil.

sulfur for blueberries aluminum sulfate for blueberries

It was unusual for me to buy boxes of sulfur and aluminum sulfate, and I was uncomfortable applying them to my soil. I try to be careful about, and aware of, what I add to my soil. In fact, these blueberry plants are the only things in my yard that I’ve added anything to besides compost and wood chips. But my blueberries were obviously struggling and my decision was between giving up on growing blueberries or adding these chemicals. I decided to try the sulfur and then the aluminum sulfate mostly as an experiment to see if they worked.

Because I’ve done so many things, I can’t say for sure what the effect of each addition has been. But my suspicion is that aluminum sulfate has had a bigger and quicker effect than anything else. After I added some for the first time last year (to lower pH), my plants showed almost immediate appreciation with less chlorosis.

It could’ve been coincidence though. Not sure. Another friend, who lives not far from me in Ramona, San Diego County and has had a handful of blueberry bushes in the ground in her yard for about fifteen years — yes, fifteen years — gets loads of production from her plants and says that she has only added sulfur to the soil.

Related to soil pH, see this presentation by University of California farm advisor Ben Faber on soil pH management if growing blueberries in the ground. And note that Faber mentions that if soil is high in organic matter — for instance, if you’ve added a lot of compost, wood chips, oak leaves, pine needles, and coffee grounds for many years — then blueberry plants in that soil will tolerate a pH somewhat higher than 5.5.

My plan now is to continue adding acidic organic matter to the soil surface and add no more sulfur or aluminum sulfate unless, possibly, my plants show that this is inadequate.

Sunshine Blue blueberry plant in full sun

Sun or shade

A planting location in full sun has given the most berries for me. I’ve grown plants in sunny and shady spots — here in my current yard twenty miles from the ocean, as well as when I lived two miles from the ocean — and while the plant foliage looks healthier in some shade, the plant produces more berries in the sun. I’m growing all but one of my blueberries in full sun now, here in the foothills of Southern California where the sun is more intense compared to the beach.

blueberry plant in partial shade

My only blueberry in afternoon shade. Its foliage is impeccable but berries are fewer.

Varieties

I’ve grown a handful of varieties, but one has far outshined the others. I’ve grown Misty, O’Neal, Jewel, Jubilee, Pink Lemonade, and Sunshine Blue, but it is Sunshine Blue that has done better for me than all of the others.

Recipe for success

If you’re trying blueberries for the first time, I’d recommend the simpler route of growing them in a large container rather than in the ground as I do. Growing in a container is more expensive, but it’s certain to be successful if you buy a big container like a half wine-barrel, buy some acidic potting soil to fill it (such as one that says it’s for azaleas and camellias). Put a Sunshine Blue plant plus one or two other varieties in there. Place the plants in full sun and make sure to water often — blueberries don’t like to dry out, in my experience, and plants in pots dry out faster than plants in the ground.

Why plant more than just one variety? It’s said that blueberries produce more when grown with multiple varieties together. I don’t know how true this is because I’ve always grown multiple varieties together. But since different varieties ripen at slightly different times and taste a little different, you might as well plant multiple varieties together.

Doing this, you’re sure to have fresh blueberries for the picking from about now (late April — we just started picking a few days ago) into June.

As for me, I’ll continue to do my best with plants in the ground. Hey — mine aren’t as pretty and productive as those in Oregon’s Willamette Valley, but they’re a lot tastier than anything I can buy in a plastic clamshell at the grocery store.

Want some deeper reading about growing blueberries in Southern California? See the University of California’s Blueberry page.