This innovative trial, inspired by a challenge from agroecology consultant Mimi Casteel, explores a variety of test plots of native grasses to solve water issues.
This is part two of the Napa Valley Grapegrowers’ Organic Field Day at Opus One. See it FREE ON SUBSTACK with photos and graphics.
Kaplow’s Critique | Multispecies Seed Mixes Planted All At Once Create Too Many Weeds
Native grasses expert Steve Kaplow, consulting to Opus One, said regenerative, current seed mix practices have problems. Kaplow was speaking at an Oakville site that Opus recently acquired and plans to add to its estate.
“I’ve looked at the ground covers and test plots in many vineyards,” he said. “One of the things I’ve noticed over and over again is that people put in all these wonderful seed mixes. Yet when I come out to do the vineyard tour, 90 percent of what I see are weeds, and I’m not seeing the ground cover.
“For most people, the common definition is a plant I don’t like. It’s a plant I don’t have a use for. It’s out of place…I have my thoughts about weeds too, but I describe it from an agroecological point of view. A weed is a plant that spreads due to disturbance. It’s what’s called in ecology a pioneer plant, and wildflowers are pioneer plants, but they’re not weeds. So what’s the difference?
“Well, weeds are plants that had a particular ability to grow with the kind of disturbance that humans make, and so they’ve been around since the beginning of agriculture. They’ve been these same weeds you see now are the same weeds that have been around for 5,000, 6,000 years, and people have been controlling them for 5,000 to 6,000 years, and they keep coming back.”
“The plants learn to adapt to it, and they’re going to keep trying to come back. You’ll see a modern-day example of this, where the plants are adapting. A lot of weeds now are becoming herbicide resistant because the plants that were vulnerable died, and the ones that are not vulnerable came back, and so now we’re getting plants that are herbicide resistant because they survive.”
To Get Past the Weeds: Mow, Mow, Mow Your Way
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Said Kaplow, “The weeds here are survivors of physical resistance, and the things we’ve been doing to mow or remove or till, they’re going to keep coming back.
“The weeds have another characteristic that makes them troublesome for me when I’m trying to do a project. These plants, when they want to grow, stick their elbows out and try to push sideways and push up, and so they try to kill all the plants around them, too, so that they can get big and they can produce seed, because pretty much all the weeds in the West Coast are annuals. They’re going to die at the end of the season. Pretty most of the weeds are dead already, but they produce seed, and they’re coming back next year from seed. So what they do is they try to kill the plants around them, get big, they produce seed.”
He continued, “All of the methods we use for doing an annual ground cover, particularly in a vineyard…are inadvertently improving conditions for weeds, because you let them get big.
“You say, ‘I’m going to let them get big. So what you’ve just done is give conditions that favor the weeds to grow, and they’re going to grow real big…You don’t want to mow it down till the end of the year. You’ve just let them go to seed, and now you’re going to mow them down, and you’re probably going to till the ground. So now you’ve disturbed the ground again. You made it easier for the weeds…you’re doing all the wrong things.”
The Right Way to Treat Weeds: “It’s A War Going On Out There”
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Kaplow has an answer for how to treat weeds: animal grazing or regular old mowing. Those favor perennial plants and natives, he said.
“What’s the timing? You don’t want the foliage to get any more than six inches…If I seed a native grass project in the fall, you’ll see all the nice, native seedlings in October, November, December. They only get about an inch or two tall the first year. They get bigger later. All their energy is going into their roots, so if you let the weeds get taller than that, any taller than two or three inches, they’re starting to grow on top of the natives. They’re starting to grow on top of your wildflowers. They’re trying to grow on top of many of the plants you really want. And by the time the weeds are six inches tall, most of what you seeded is probably already dead. And so it may look all peaceful and green, but it’s a war going out there, and the weeds are going to win. And if you don’t control them, the weeds win.
“It’s a matter of keeping it mowed low, particularly for the first couple of years, because you’re trying to suppress the weeds, keep them from killing the natives, and keep them from reproducing, so you want to keep the weeds short.
“You don’t want them to go to seed, and that’s that’s the mowing system. It gets less intense as years go by. In the first year, you might be mowing three, four times,” he said. Opus said it had already mowed four times by July 22.
Frequent mowing means gentler mowing. “Because you were mowing often, there wasn’t a whole lot of foliage to mow, and so it wasn’t rough on the equipment. It was almost like mowing your lawn, a little more than that, but on that basis,” Kaplow said. “So repeat mowings through the growing season, and then in the summer you can let it go.”
“[If you wait till the weeds get high,] you’re dealing with a lot of thick, tall stuff that’s going to bind up with your mower and wear your equipment out. But if you mow more often–yes, there are more mowings, but they’re easier and faster, and it puts your vegetation in a much better place…Eventually the weeds grow under control, and then you can start getting the vegetation you really want.”
Little Strips of Prairie Grass
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Kaplow recommends native perennial grasses over annuals.
“They have certain major advantages over the annuals that you’re using. When you look at the grasses, you’re going to see foliage even in the height of the growing season. They may only get six inches tall if you didn’t mow them. They don’t get tall. They’re little bunchgrasses, but underground, they’re putting roots that are going down five or six feet, and they’re putting a lot of carbon into the ground.
“Around the world, it’s well known that the soils with the highest amount of soil carbon are all grassland soils. They’re all prairie soils. So, in a sense, what I’m talking about doing here is putting in strips of linear prairie into your vineyards.”
Carbon Sequestration and Microbiome Advantages of Native Perennial Grasses
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“If you want to put the carbon in the ground, you have to let the roots do it,” Kaplow said.
Kaplow said the native grasses inject a lot of carbon into the soil and create a stable environment for the beneficial bacteria and fungi to grow. “Versus, if you have annuals, their roots only go down about a foot, and they’re going to die at the end of the season,” he added. “So you’re kind of starting from zero again for the microbial community, or at least their habitat is pretty much starting from zero. Whereas with perennials, you have a stable environment, and you can get the microbes to grow much better.
“Perennial grasses are very good for mycorrhizal association, bacterial association. So if you’re trying to get soil microchlora, perennial grasses are a great way to go.”
Native Grass Establishment: “Like Prepping a Canvas”
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Kaplow said he loves wildflowers but recommends waiting until the native grasses are established before planting them.
“The first step you’re trying to do in a perennial cover,” he said, “is get a stable background. It’s almost like prepping a canvas. You’re trying to get a stable surface that’s going to be weed resistant, and as the perennial grasses grow, their roots are going to fill the soil, and they’re going to basically make a wall of roots. And when weeds try to germinate in that; their roots are going to hit the native grass roots, and they’re going to stop.”
He is not an advocate for planting legumes as cover crop for nitrogen. “If you don’t need the nitrogen, don’t put the legumes in, because they’re going to harbor a lot of pests. Too much nitrogen in the soil creates a weed problem. If you don’t need the nitrogen, don’t do it. If you do need the nitrogen, absolutely, that’s not a question. But if you don’t need it, don’t do it,” he said.
Kaplow cautioned against using fescues and bluegrasses. “I didn’t use any fescue or bluegrass in this project, and the reason is that I’ve worked with them in restoration projects a lot, and fescue and bluegrass are northern grasses. They’re moist site grasses. If you are in Washington State, it’s a no-brainer. If you’re in British Columbia, absolutely.
“There are native fescues and bluegrasses here, but they’re on the north side of a hill. They’re in the shade of trees. They’re in the fog belt next to the ocean.
“You don’t see them wild out here. You can seed it, and you will get scattered plants. But you’re not going to get reliable results. You’re not going to get a full cover. It certainly won’t live. So that’s the only reason I didn’t try those.”
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Bentwood grass
Seeding Is A Bit of An Art Form
McGraw cautioned, “With native grass seeding you really have to be careful. The seeding rates are so low. You say, ‘Oh, I bought seed for five acres,’ and you use it up after one, because ‘it just doesn’t look right.’ You seed it, and you don’t really see anything, and you go, ‘I’ve got to put more. Well, by the time you did, you’ve overseeded. So you really have to learn to stretch it out.
“Sometimes what people do is they will mix it with rice hulls, or they’ll mix it in with something else to spread it out, so that it looks better…It’s as light as humanly possible, and even then, you’re probably putting it on too heavy. So that’s a major case of self-control.”
The rest of the morning was devoted to grass plot by grass plot inspection.
Kaplow said that even after just one year, some of the grass roots would already be about three feet deep.
“They’re reaching for water. They’re trying to make it through the summer. Now eventually they’re going to be six, eight feet deep. They’re going to hit the water table at some point. Maybe they have, but I don’t know. They’re still young.
“Eventually they’re going to not only grow down but sideways, and the root systems can start banging into each other. So it’s going to become a wall of roots…each year it gets a little more like that.
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California oatgrass (Danthonia californica) is old-growth grass in California is a long-lived native perennial bunchgrass that can live for up to 200 years and helps sustain ancient meadow ecosystems.
“Danthonia has a very, very long term strategy,” said Kaplow. “This grass, when it’s going, will live 120 years. It would be an old growth kind of grass. This is the redwoods of the grasses, but it’s hard to start it.
“I’m not quite giving up on it for here because that is one that will stay green and will dry this field out if that’s what you need,” Kaplow said. “It’s long lived and once it’s in, it’s in forever. It’s just a great plant. I have high future hopes for it. I’ve got this growing in my front yard in Santa Rosa. I don’t water it and it’s still green.”
The final event in the NVGG organic series on July 29 featured a keynote conversation featuring two respected organic producers-Steve Matthiasson of Matthiasson Wines and Jason Haas of Tablas Creek Vineyard.
That will be the subject of a future post here.
UPDATE: The SF Chronicle published a new article on the winery's new eco-direction.
