No-dig gardening is a simple gardening method that many gardeners — who were taught for years that they had to till or turn their gardens annually — still have many questions about. To demystify no-dig gardening and explain its benefits, my guest this week is my longtime friend Charlie Nardozzi, a nationally recognized garden writer, speaker, and radio and television personality.
Charlie lives in and works from Vermont and hosts public television’s “New England Gardening.” He also previously hosted the national television show “GardenSMART” on PBS — a show that I hosted myself after Charlie. He delivers talks and Master Gardening presentations nationally and has led garden tours throughout Europe and the Americas. He is also renowned for his writing, and his seventh book, released in December 2020, is “The Complete Guide to No-Dig Gardening,” a friendly, easy-to-read book with great illustrations.
While tilling has been the norm in gardening and agriculture for a long time, it’s not the best way. As soil science has increased our understanding of the soil food web, it has become more and more clear that tilling is bad for the soil. Tilling wipes out microbes and releases carbon, while no-dig gardening provides a rich soil environment for plants with much less work on the gardener’s part.
No-Dig Gardening Goes Back to How Things Were
Like the Hippocratic Oath for medical doctors — “do no harm” — the idea behind no-dig gardening is to refrain from harming the soil. Charlie explains that tilling and turning destroys the soil structure that naturally develops when soil is undisturbed.
Charlie points out that, in the long history of gardening and agriculture, it’s only relatively recently that tilling and turning the earth became a common way to try to increase production. No-dig gardening is a return to how farmers operated historically.
Natural ecosystems, like a forest or grasslands, just grow — and no one is turning the soil or fertilizing, Charlie says. The idea behind no-dig gardening is to mimic a natural ecosystem by allowing the soil to develop its natural structure, life and vitality. As a result, the plants grow better, there is less work to do, and fewer disease and insect problems arise.
Soil that hasn’t been tilled is also more effective at sequestering carbon, so no-dig gardening is a tool to combat climate change. Charlie says when millions of gardeners collectively switch to practicing no-dig gardening, it will have a dramatic effect.
Tilling also uncovers countless weed seeds in the soil, exposing them to light and causing them to germinate. But when you practice no-dig gardening, positively photoblastic seeds will stay dormant indefinitely.
Picking and Preparing a No-Dig Garden Site
Like with any garden, choose a sunny spot that will give you the most options for what you can grow. However, Charlie says a spot in partial shade is okay too, as long as you choose plants accordingly.
It also helps if a site is close to a water source and won’t be out of sight, out of mind. “Keep it close so that you walk by it every day,” Charlie says. “Because as the old saying goes, the best-tended garden is the one that has the footsteps of the gardener in it.”
If starting a garden on a lawn, mow the grass down low — there is no need to remove the grass completely unless it is a hard-to-kill grass like Bermuda or quackgrass. If starting in a weedy area, cover the weeds with flattened cardboard boxes with the tape and staples removed. For really aggressive weeds, consider using a geotextile — though Charlie notes that a geotextile barrier between native soil and the garden bed should be avoided when practical.
A 12-inch-high garden bed will be more susceptible to rhizomatous weeds than a taller bed, so Charlie recommends going as high as 3 or 4 feet as an alternative to using a geotextile.
Rather than preparing an area to plant a garden immediately, you can plan a year ahead. Pick the spot and put down multiple layers of cardboard to smother weeds. Alternatively, cover the spot in a plastic sheet to solarize the weeds and seeds in the sun. Weakening and killing weeds upfront will save a lot of work later on.
Layering a No-Dig Garden
No-dig gardening uses layers much like a compost pile: Layer “brown” and “green” materials as high as you desire, but a minimum of 10 or 12 inches high.
Brown materials are carbon-rich, such as leaves, straw, shredded paper and cardboard. Green materials are nitrogen-rich, such as fresh grass clippings and coffee grounds.
“The fun thing about no-dig is that you don’t have to go out and buy a lot of the organic matter materials, like you would building a regular kind of bed,” Charlie says. Rather than buying topsoil and finished compost, you can just look around for what’s already on your property.
In Charlie’s case, he used the hay and grasses that existed on the abandoned meadow where he built his home. On the coasts, chopped seaweed rinsed of salt is a good layering material. Near a forest, use chopped leaves.
Whatever the layers are, cap the top with finished compost. The layer of finished compost will inoculate the materials underneath with the microbes necessary for decomposition.
In a temperate climate where microbial composting activity slows down or stops in winter, start building a garden in April or May and use an extra-thick layer of compost, Charlie says. In a warmer climate, begin in the fall or winter, allowing the materials to break down for several months, after which they can be planted into.
Planting in a New No-Dig Garden
Because a brand-new no-dig garden does not have deep soil yet, it is a good idea to plant shallow-rooted crops early on. Cool-season crops like lettuce, arugula and radishes are perfect for this.
Later on, the layers of materials will be broken down further and will be better primed for deep-rooted, warm-season crops that don’t require many nutrients, like peas or beans. These legumes are also nitrogen-fixing crops, which will benefit the crops that are planted in later years.
In its second year, a no-dig garden will be better suited to deep-rooted heavy feeders, such as tomatoes and squash.
Cover Crops on a No-Dig Garden
In his book, Charlie lists cover crops that don’t need to be tilled into the soil. Instead, he selected cover crops that will naturally die in freezing or subfreezing temperatures. Come spring, all the gardener has to do is top off the cover crops with compost. Some of these include annual ryegrass, field peas, mustard, sorghum grass and Japanese millet.
“Cover crops are a great way to not only build the soil as you’re getting started, but to continue that maintenance as you’re going along,” Charlie says.
Alternative No-Dig Gardening Method: Straw Bale Gardening
Straw bale gardening is a growing method that is fully no-dig. It starts with a straw bale conditioned with a nitrogen source, such as blood meal. The nitrogen and carbon-rich straw interact and the bale really heats up as microbial activity breaks the straw down and nutrients are released. Vegetables are planted right into the straw bales and may never come in contact with the ground.
Joel Karsten, the man who literally wrote the book on straw bale gardening, has been a guest on the podcast, and you can listen to our conversation for a comprehensive explanation of how it works.
Alternative No-Dig Gardening Method: Hugelkultur
Hugelkultur gardening is a method of growing on mounds of logs and twigs covered in other organic materials. Those logs can last as long as 20 years as they slowly break down, releasing nutrients into the soil. The mound will sink as materials decompose, and more organic material can continually be added to the top. The result, over time, is a very fertile mound where, in addition to annual crops, berries and even trees can grow.
Generally, putting carbon material close to roots is problematic because the carbon sources will take nitrogen from the soil as they biodegrade. However, in hugelkultur the logs are a base layer distant enough from the surface so there is no concern about the carbon-rich logs depleting nitrogen from the soil when the plants need it.
Hugelkultur is a great way to get rid of waste logs, and logs from deciduous trees are the best, Charlie says. Woods that naturally contain chemicals that inhibit the growth of other plants, such as walnut, should be avoided. Softwoods should be given a year to age before burying so the resins and saps have a chance to break down first, he adds.
The logs also retain moisture, so a hugelkultur garden, once wet, tends to stay wet.
Alternative No-Dig Gardening Method: Keyhole Gardening
Keyhole gardening is a permaculture technique that uses a raised bed in a “C” shape, so there is a pathway in the middle like a keyhole. This maximizes planting space while allowing easy access to the garden from within the keyhole or around the perimeter.
Dr. Deb Tolman, the founder of The SILO Project (Sustainable Information and Learning Opportunities) advocates the use of keyhole gardens. She uses cardboard and manure — and no native soil. A central basket is filled with kitchen scraps to continuously fertilize and water the garden. (Charlie recommends this video of Deb and children building a new keyhole garden with cement blocks, cardboard and phone books.)
Alternative No-Dig Gardening Method: Ruth Stout
In the mid-20th century, Ruth Stout pioneered a type of no-dig gardening that involves keeping a deep layer of hay mulch on the garden permanently. Not only did the hay suppress weeds, her plants grew well.
This method is named after Ruth Stout and also known as the “no-work method” — because it is that easy.
Charlie notes that this can also be done with straw, leaves, or any organic materials a gardener has around the yard already.
No-Dig Gardening in Urban Environments
No-dig gardening is a smart choice in urban environments or anywhere that planting in the native soil will be a risk.
“In urban soils, you can have all kinds of things underneath that soil layer, especially if you’re in a city or a town that’s been there for generations and generations,” Charlie says. “You have no idea what was there before.”
He says that once you start digging down, you might find not only contamination but physical objects, because builders often just bury stuff as they put up houses.
To prevent contamination from working its way up or the plant roots from getting down into contaminated soil, you can also put a geotextile down on the native soil before building a garden on top.
Test Soil for Silt, Clay and Sand Content
Before starting a garden, it’s good to know the composition of your soil: How much of it is silt, sand and clay. Each one has different characteristics, and the amount of each will affect how soil holds water or drains.
An easy method to find out the make-up of soil is known as the “jar test.” Take a quart jar with a lid, fill it a third of the way with soil, and then add water until the jar is nearly full. Add a dash of liquid dish soap to help the materials separate, then shake the jar vigorously for a minute. Let the jar sit for 48 hours, and then observe the different layers: Sand at the bottom, silt on top of the sand, and clay at the very top.
If you have 50% sand, you’ll know you’re going to be watering often because the water will drain through it, Charlie says. If you have 60% clay, you’ll know that the soil will need to be covered by mulch at all times.
Another method is known as the “ribbon test.” Charlie explains that it starts with a handful of soil. Wet it, squeeze it, and roll it between your palms — try to make a ribbon out of it. If you can’t make a ribbon, the soil is mostly sand. If you can make a small ribbon, the soil has plenty of clay in it.
The “feel test” just involves rubbing soil between your fingers. If it’s gritty, it’s sandy. If it’s slick, it’s clay. “It’s pretty simple stuff, but sometimes the simplest stuff is the most helpful,” Charlie says.
The drainage test starts with digging a hole that’s 1 foot in diameter and 1 foot deep. Fill the hole with water and let it drain, then immediately fill it with water a second time. If the hole has completely drained a few hours later, the soil may be draining too fast. If eight hours or so later the water hasn’t drained at all, it’s probably not a good place to plant, especially a perennial, Charlie says.
A slow-draining site that is sunny and meets other criteria can still be used for a garden, but you’ll have to build the soil up rather than digging down, he adds.
Hardpan Metal Rod Test
Another test Charlie recommends will determine if there is hardpan underneath the topsoil. Hardpan, or soil pan, is a soil layer that water doesn’t move through. They don’t call it hardpan for nothing — it’s rockhard. Most roots will not be able to penetrate hardpan, and the garden will not drain as it should.
The “hardpan metal rod test” starts with a metal rod, like a length of rebar. If you stick the rod into the ground and it will only go 8 or 10 inches deep before it stops, you’ve either hit a rock or hardpan. Repeating the test in multiple spots will help you distinguish between a random rock and a consistent hardpan.
Related to hardpan is “tiller pan,” which is created after years of tilling soil. Running a tiller over a garden will create soft, fluffy soil only as deep as the tines of the tiller, and the soil underneath becomes compact in the process.
If you haven’t already listened to my conversation with Charlie Nardozzi on no-dig gardening, you can do so now by scrolling to the top of the page and clicking the Play icon in the green bar under the page title.
Do you have success practicing no-dig gardening? Let us know in the comments below.
Links & Resources
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joegardener Online Gardening Academy™: Three popular courses on gardening fundamentals; managing pests, diseases & weeds; and seed starting.
joegardener Online Gardening Academy Master Seed Starting: Everything you need to know to start your own plants from seed — indoors and out.
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