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.

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 doesn’t live far from me 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.

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

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.

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.

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.

When and how to prune citrus trees

When and how to prune citrus trees

The other day I had a good time giving a talk about growing citrus to the Lake San Marcos Garden Club, and a couple of people asked me about pruning. My impression is that most of us think that, as a general rule, all fruit trees need to be pruned. It’s simply not true, especially regarding citrus. In contrast to this mistaken notion I’d say that, as a general rule, citrus should not be pruned. I can think of only a couple of exceptions to this rule.

In my yard I grow eight citrus trees, and out of those eight I only ever touch two with my pruners, each for a different reason.

PRUNE TO KEEP A CITRUS TREE SMALL

I give our Bearss lime tree haircuts because I want it to stay small, to about the height of my three year-old son. It already produces more limes than we use at that diminutive size. Once a year I prune it by just trimming off every branch that is taller than I want, or by handing Cass the pruners.

pruning a citrus tree to keep it small

Five year-old lime tree being pruned by a three year-old boy.

PRUNE TO SHAPE A CITRUS TREE

I also prune our large Valencia orange tree. It’s 25 feet tall, and I’ve never tried to trim the top. Rather, I prune the sides and interior to create an umbrella shape. I keep its skirt a few feet off the ground and then I keep the inside pruned high enough that we can walk around under it so that it feels like an outdoor living room. I prune up a couple of spots on its canopy edge to make doorways for entrance. Shaping this citrus tree in this way makes it a very comfortable spot to sit in the shade on a summer day.

Valencia orange tree

swing in orange tree

I’ve even hung a swing from one of its branches.

Keeping a tree small like my lime and shaping a tree like my Valencia are the only two good reasons I can think of for pruning citrus. There are plenty of bad reasons though.

DON’T LACE A CITRUS TREE

The worst reason, or way, to prune a citrus tree that I’ve encountered is opening up the tree’s canopy so the interior gets sunlight. That can be a good idea for some other types of fruit trees, like plums and peaches. It’s definitely not advisable for citrus, however.

Why not? I once did a home consultation at a multi-million dollar residence in Rancho Santa Fe where the owners had put in an orchard of a few dozen fruit trees and then their hired gardener had pruned all of the citrus trees just like the peaches and plums. The foliage had been thinned, entire branches had been cut out, the canopies had a skeletal look, and the effect was that you could see lots of light going through the trees and hitting the interior branches.

Why are our citrus trees dying? the owner asked me. All of those interior branches now exposed to the sun were cracking and blackened from sunburn. Yes indeed, trees get sunburned.

If you want to keep a citrus tree small or shape it, then trim the outside like you would trim a hedge. Don’t cut out entire branches and expose interior parts of the tree that are used to being shaded. Have a look at this video showing how citrus farmers mechanically prune their trees. This farm is in Spain, but the same technique is used here in Southern California, and the world over.

A citrus expert once told me that if a citrus tree is in prime health, then if you look at its canopy you won’t be able to see any light or sky through it. It should be a dense green globe.

A couple of other no-good reasons to prune citrus include cutting out dead or crossing branches. That’s just a big old waste of your time. Do it if you have nothing better to do, but your citrus tree couldn’t care less if some of its branches are crossing or are dead and hanging. Both are harmless and natural. I don’t cut out any dead or crossing branches on my citrus trees and they’ve never complained about it.

insect damage citrus tree

Also, if aphids or leafminers or other insects have damaged the leaves of your citrus tree, don’t waste your time cutting those damaged leaves out. They’re still capable of photosynthesizing and contributing to the growth and fruitfulness of the tree even though they’re not completely healthy. Pruning them out won’t make a significant difference to the insect population in the tree either. Better to adjust your aesthetic sensibility than cut up the tree, in terms of the health of the tree.

Lastly, and here’s a bit of a twist, do pay attention to what’s growing from low down on the trunk of your citrus tree. I don’t think of this as pruning, but it’s really important that if any branch starts growing from below the graft (bud) union of your citrus tree you immediately remove it. If you’re unsure of what I mean by that, then please read my post titled, “Beware of rootstock suckers on citrus.” It might save the life of your tree.

Isn’t it a relief, though, to know that your citrus tree knows how to grow pretty well on its own? That’s why you can find citrus trees thriving even in Southern California yards that have been neglected for years. And that’s why every Southern California yard should have a citrus tree, or eight.

 

You might also like to read:

Don’t spray for citrus leafminers

Oranges and mandarins fresh off the tree almost all year

What to do in a Southern California garden in April

What to do in a Southern California garden in April

In April, my gardening mind is busy, as I suspect is yours. Mostly, I think about three topics. The first is fruit set — flowers becoming fruit on the trees. The above photo is the fruit set on my Blenheim apricot today; this tree is an over-achiever, year after year. A few of my other trees should take lessons . . . are you listening, Snow Queen nectarine?

And then I start thinking about irrigation this month too. It’s likely that we won’t get another real rain. Up ahead is about seven months of sunny and warm. I’ve always thought of growing food in Southern California as “just add water” because we have all of the sun we could want and none of the nasty weather (hail, high winds, flooding) that other places have in the summer. We just don’t get water from the sky during this time of year, so adding that is up to us.

April isn’t the month when a lot of watering is required, of course. But being the beginning of the irrigation season, it is the best, most forgiving time to fiddle with systems and dig down to test percolation and figure out schedules. On the other hand, doing this right before you’re about to leave on vacation in the summer would be the worst, least forgiving time. I think of time spent preparing irrigation now as doing my future self a favor.

And April begins open season on planting vegetables that like to grow through summer. It’s so exciting to now be able to freely sow and plant peppers, tomatoes, melons, eggplant and, well . . . here are the details on what we can sow, as well as other timely tasks out in your food garden in Southern California in April:

– Sow or plant vegetables: beets, carrots, basil, greens, tomatoes, tomatillos, sunflowers, squash, corn, beans, peppers, eggplant, cucumber, melons

– Eat vegetables (had you planted them): peas, broccoli, cauliflower, cabbage, brussels sprouts, greens, carrots, beets, lettuce, parsley, cilantro, spinach

– Eat fruit (if you have the trees): avocados (Hass, Fuerte, Pinkerton); citrus (Valencia, Gold Nugget mandarin, Pixie mandarin)

– Eat, eat, eat strawberries, and freeze, freeze, freeze the ones you don’t

strawberries in April

– Prune deciduous fruit trees with only a twist of your fingers; if you made a heading cut in the winter and new shoots are sprouting below it now, just remove any of those shoots that you don’t want by snapping them off with your hand — it’s really that easy

– Get excited about fruit set on deciduous fruit trees and, should you be so lucky, consider thinning some fruit; if a skinny branch has a lot of fruit toward its tip then it’s wise to remove some fruit there so the branch doesn’t break under the fruit’s weight (peaches or nectarines) or get sunburned as the branch bends down (apricots, plums, apples); that being said, don’t bother thinning much more than that

Flavor Grenade pluot fruit set

Flavor Grenade pluot fruit set; I will thin some, especially toward the tip

– Get up close and enjoy the smell of the citrus blossoms on the trees in your yard

– Cut off the water to garlic and onions that you planted last fall as they bulb out toward the end of the month; they can finish their lives on residual soil moisture, and they’ll be dry and easy to harvest when their leaves yellow and die sometime in May

– Get gophers before they get your plants; there are a lot of young ones under the ground this time of year, and the best way I’ve found to keep them under control is the Cinch Trap

– Set up new irrigation on plants, test run all irrigation lines to check for clogs and leaks, flush drip irrigation lines, clean out filters — get that irrigation dialed in

 

You might also like to read:

How long to run drip irrigation on vegetables

What is the best time of day to water your plants?

What is the best time of day to water your plants?

Looks like the irrigation season is upon us. My yard hasn’t been rained on in over a month now. As you start to water your plants for maximum yield and efficiency you might wonder, as I often have, what time of day is best: morning, afternoon, evening, middle of the night?

Whenever you can be watching — that’s my operating principle.

When I say this I’m thinking of what time of day it’s best to run an irrigation system, like a set of drip lines in a vegetable garden or mini-sprinklers under fruit trees. And what I mean is that it’s best to run that system at a time when you are usually home and able to observe. For example, if you leave for work every day at 6 a.m., then it’s best to run your irrigation at maybe 5 p.m. when you’re home from work, not at 7 a.m. while you’re gone even though both 7 a.m. and 5 p.m. are perfectly fine times of day to water plants.

I think that being able to watch your irrigation system run is vital because of all of the things I’ve noticed over the years while watching my systems operate. I’ve noticed clogged drip emitters, mini-sprinklers that needed a flick to get them spinning again, a leak in a valve, a drip emitter that I forgot to plug up after the plant it was watering died, and on and on.

My system was running just the other day when I heard a curious spraying sound. I dug to find this:

Irrigation leak

If you’re around to watch while your system is running, then you can catch these things red-handed rather than read the evidence of a dried-up plant or a mossy spot in the soil after the problem has been long occurring out of sight.

If you’re watering by hand using a hose or sprinkler or watering can, then of course you’re going to be watching, so is there a best time of day for that? Morning and evening are both great there too. I’d say that only noon in the middle of summer is not ideal, and that’s because you’re going to lose a little more water to evaporation at that time. But who would choose to stand in the sun in the middle of the day in summer anyway?

One thing we don’t need to worry about here in Southern California is the idea that watering in the evening or at night and wetting the leaves of plants might encourage fungal diseases. That might be a consideration in more humid climates, but it’s a non-issue here. I’ve watered and wet leaves in the evening some years and never wet leaves other years, and I’ve seen no difference in the incidence of diseases like powdery mildew and downy mildew — and that’s both in my gardens near the ocean and in the relatively drier inland areas. My observations have been that mildew hits plants like peas and squash as they age regardless of the watering regimen, and the occurrence of botrytis on blackberries is mostly due to insufficient sunlight, not wet foliage and berries.

mini-sprinkler under avocado tree

What do I currently do in my yard? I run mini-sprinklers under my fruit trees in the late afternoon, usually starting around 4 p.m. I like this time because the common west-northwest breeze coming from the ocean is starting to slow down, but it’s still not totally calm; having some movement in the air helps distribute the sprinklers’ droplets a little more broadly.

And I run drip lines in my vegetable garden in the morning around 7 a.m. This is because I’m often at home at this time, and I can “walk the lines” briefly to check on them.

When can you be watching? That time is the best time for you to water your plants, in terms of their health and the efficiency of your water use in the long run.

 

My boy and his placenta tree turn three

Kids grow fast, as do avocado trees — especially when planted over a power-packed placenta. Oddly, prior to looking through the retrospective below, I had felt rushed for both of them to hit some developmental marks even faster.

As of today, Cass can legibly write most of the letters in his name, but he continues to do this curious thing where he writes his c’s backwards.

And as for his Fuerte avocado tree, my aim has been that it produces fruit for Cass to eat and that it develops a broad branching structure for him to climb. The tree is healthy, but it has yet to produce fruit, and it’s not yet big enough for Cass to climb.

Alas, sometimes you get focused on goals, on achieving results, but miss the wonders of the process along the way.

Cass and placenta tree at birth

Just planted and just born, 2014.

Cass and placenta tree one year old

One year old, 2015.

Cass placenta tree two years old

Two years old, 2016.

Cass and placenta tree three years old

Three years old, 2017.

I’m determined to enjoy processes more. We’re not promised another day on this Earth. The process is really all we have.

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