By Stacey Warde.
It didn’t take long to come up with an answer. A profusion of growth from pushing the blueberry plants with specially designed nutrients had left us with spent, twiggy branches and tired leaves that needed to be removed.
Most of the plants performed well through the harvest season, producing berries upon berries, and seeming never to end, mostly because we had earlier pumped them up to develop the stout healthy canes that support heavy clusters of juicy blueberries.
Now that they’ve finished producing, the old stalks on which the berries grew need to be removed.
In the few short months leading up to harvest time, the plants transformed from twiggy little starters into flourishing, bushy woody container plants with lots of berries. So much growth and fruit tended to make the plants top heavy until we began to secure them to prevent them from toppling over.
On one blustery day, for example, I picked up more than 400 plants that had blown over in the wind. Soon after we began to stake them down.
The southern highbush varieties that we grow perform well in the temperate climate and coastal sage scrub zone back here in the serpentine-rich hills of Cayucos. The blueberry plant is a woody perennial that can get up to 10 feet high. In these container bags, however, they’re somewhat limited to how large they’ll grow.
I’ve visited a couple of blueberry fields in the area in which the plants are growing in amended heavy clay soil, which is an enormous undertaking, and they don’t seem to have the vigor that our plants do in their container bags.
I attribute the difference to the greater controls that the bags offer. Our heavy alkaline clay soils are the hardest for blueberry plants grow in and must be amended with peat moss and an infusion of acid into the irrigation to break down the alkalinity in the water. Blueberries thrive in soils with a ph balance of 4.0 to 5.0, which leans to the acidic side.
Tests of the soil and water where we are growing our blueberries, and which would probably be true for much of San Luis Obispo County, have shown a ph balance of 7.5 to 8.0, too much alkalinity for blueberries to draw nutrients and thrive.
Nonetheless, we’ve managed to produce lively, thriving plants by keeping them in their containers, limiting the alkalinity in our plant medium and water by adding the right mix of soil amendments and nutrients into the bags.
This first mature season, for example, our three-year-old plants reached heights of four to five feet, even in their small containers, producing an abundance of woody branches that now need to be pruned and trimmed.
Oddly, as moderate temperatures prevail in the waning summer days, new flowers have begun to appear, and in scattered locations throughout the field fruit is developing. It’s starting to look like spring again as we head into fall.
The same thing happened last year and I thought incorrectly that we might get a late fall harvest. The berries then had little of the flavor and texture of this year’s spring and summer berries. They were mushy and tart, not sweet and delicious.
The plants have worked overtime and need to take a break. We’ve decided to prevent any more blooming and fruiting, and will now attempt to make the plants rest from production.
“We need to force these plants to go dormant,” said Zsu Zsi, who has taken over management of the field from her husband who teaches full time at the university. “We need to train them, make them do what we want them to do.”
That means hard pruning, she said. I was opposed to a hard approach and wanted to go easier on the plants.
Zsu Zsi grew up in Hungary and spent time as a youngster working in her grandfather’s vineyard. She has her own ideas about trimming and pruning. She had already gone heavy on some plants at the south end of the field, in some cases cutting into the heart of the main stalk, causing me no end of distress.
“If you cut that deeply,” I protested, “you’ll put the plant in danger. You’re exposing it to unnecessary risk of disease or pests. I might agree with the deeper cuts if these plants were rooted in the ground but they’re not. They’re too exposed.”
“I have an intuition about how to do this,” she responded.
“Intuition is fine,” I said, frustrated, “but pruning is more of an art and science.” The idea behind any pruning, of course, is to reduce the risk of disease and pests by cutting away the old dead and diseased growth and invigorating the plant for newer, healthier growth.
I’ve never worked in a vineyard and perhaps there’s an element of intuition involved after spending years in the shadow of an experienced grower but I doubted that it was the best course to take for our container farm.
Intuition made more sense to me for plants firmly established in the ground and for a person who has years of pruning experience, where it becomes second nature. Additionally, the growth and pruning needs of vines and woody perennials may or may not be the same, and there’s a huge difference between a plant in the ground and one in the bag, I argued.
It went on like this for several days until finally Zsu Zsi spent half a day online researching how to prune blueberry plants. We were then able to have a discussion based less on guess work and intuition and more on studied data and experience.
“I spent almost five hours on the internet,” Zsu Zsi said, “researching the best way to prune blueberry plants.”
“That’s great! What did you find out?” I asked. I’d seen some of the same data she reviewed.
She took me to a plant that needed pruning and began to whack it with the loppers, shearing off a huge piece of woody branch, close to the heart of the plant’s crown, holding it up victoriously.
“That’s how you’re supposed to prune,” she said.
I was horrified.
“You can’t do that!” I protested. I touched the fresh wound, examined the cut piece, and lamented: “That’s too close to the heart of the plant.” We haggled over the best pruning methods—again.
“Look, Zsu Zsi, let’s not cut so close to the bone. I’ll agree with you and go for the heavy pruning as you suggested, even though I still think it’s too early in the season; there’s still some risk of heat, but let’s at least agree to leave a margin, leave some room for new growth to appear. These cuts don’t leave room for any new growth.”
We agreed to be less severe, still stripping the plants down until nearly bare, leaving only a few stalks, and heavily pruning the old wood. It may not be pretty, and I still think the cuts are premature for the time of year, but we at least agree that our goal is to do what’s best for the plants.
We’ve completed the pruning of the amazing Snow Chaser variety, about 400 plants, which are the first variety to come on line with what I consider to be the best berries we grow. The rationale is that since they produce the first fruits, we’ll give them a head start on next season’s growth by pruning them first.
It’s taken about a week for three of us to do the heavy pruning of the first variety. Next, we’ll attack the Jewels, another fine variety with larger, plumper berries that come on line a couple of weeks after the Snow Chasers. And finally, we’ll end with the Emeralds, which seem to suffer most from lack of pruning.
The Emeralds have been in the bags longer than the other varieties and have become root-bound, producing twiggy suckers and little new healthy growth. These will require an entirely different approach. Not only do they need pruning above, but below where the roots have become tangled.
They’ll have to come out of the bags and put in new containers. That’s a project for the near future. Meanwhile, the field is starting to look barren, as if winter has swept through and removed all the old tired growth.
Stacey Warde is a regular contributor to Green Living Press and author of the Farm Hand Diaries: an Insider Look.