I’ve tried various methods of making a garden bed.
Years ago, I invested in building a raised-bed vegetable garden with rot-resistant 2-by-12 lumber. It has served me well, as have the in-ground beds that were heroically double-dug, adhering to the soil-preparation practices of the modern organic farming pioneers Alan Chadwick and John Jeavons.
I hope those heroes will forgive me for lately turning to a more passive approach, aided by recyclables (namely, corrugated cardboard and newsprint) and occasionally by thick, reusable clear-plastic sheeting. These days, I smother and solarize — two powerful weed-control tactics for organic growers.
Besides the ease and the low budget — a sunny patch of lawn can be transformed in time for planting strong growers like tomatoes, pole beans or summer and winter squash — there is an additional long-term benefit to what might seem a lazy person’s approach. Prepping a bed without turning or tilling may actually help reduce the number of weed seeds that are unearthed and then germinate. Less work now; less weeding later.
Assess the Site
Whatever prep tactic you’re using, and whichever material, you should begin by identifying an area where the soil is neither sodden nor impossibly dry. If you’re planting vegetables, herbs and most annual flowers, choose a spot in full sun. A basically flat area will be easiest for both prep and aftercare.
For first-time vegetable gardeners: Start small, with 100 square feet in a 5-by-20 bed (any wider and you won’t be able to reach the middle from the sides) or two 5-by-10s.
What’s growing on the site now will determine any preliminary steps, as well as the method you use — that is, whether you should smother the area with paper or solarize it, applying clear plastic to heat the soil and kill the weeds. Or whether you need to do both in succession.
Is the site mostly open soil, with a few herbaceous weeds — maybe a former garden bed? If there are perennials tougher than turf grass or any woody weeds, use a spading fork or shovel and remove them carefully, which is easiest in moist soil.
If there are no serious weeds and you’re hurrying to plant, use cardboard. Better still, start two sunny weeks earlier and solarize first (more details on this below); always do this extra step in infested areas, where perennial weeds will require more than two weeks to subdue.
But before paper or plastic goes down, the soil must be moistened. Then the material should be weighted down, whether with earth staples (which resemble giant hairpins), rocks or lumber, like two-by-fours. Plastic edges can be buried, and paper mulches must be moistened once in place.
The Cardboard Method
If what I’m planting is neither delicate nor tiny, and I’m not battling tenacious weeds, my default prep is cardboard. Yes, cardboard and newsprint are safe for mulch (and even to compost). Use the plain brown stuff, not the kind printed with colored ink (although most ink today is soy-based). Likewise, collect black-and-white newsprint, not glossy magazines, and strip off tape or staples from corrugated cardboard.
Then simply place a thick layer of newsprint or flattened cardboard over freshly weeded soil or turf mowed or weed-whacked to stubble. Overlap the pieces so there are no gaps for weeds to exploit. Remember to moisten the paper, and secure it.
If I can get good, crumbly compost, whether bagged or delivered in bulk, I’ll cover the cardboard to a depth of several inches and plant right into that medium, in the style of the British horticulturist Charles Dowding, a longtime advocate of no-till gardening. Otherwise, I’ll cut X’s or circles into the moistened, weighed-down cardboard, creating little planting pockets into which I add some compost before sowing several winter squash or pole bean seeds in each pocket or positioning a tomato seedling. Then I’ll cover the paper areas with the best mulch on hand, even a thick layer of rotted leaves.
The pocket method also makes an easy bed for landscape shrubs, or quart-size or larger perennials (although the openings will be larger than for a tomato transplant or a few squash seeds).
One caveat about paper mulch: It can be hydrophobic, repelling water and depriving plants of it. Don’t just set it and forget it, or plants will suffer. Water the bed before mulching, after applying the paper and regularly as plants grow.
How Solarization Works
Whether as a preliminary step before mulching, or on its own, solarization is a formidable chemical-free weed-control strategy.
“Soil solarization is the practice of covering moistened soil with clear plastic for a period of weeks, to create a local greenhouse effect,” said Sonja K. Birthisel, a postdoctoral research associate at University of Maine, who focuses on ecological weed and pest management in a changing climate. Water molecules in the soil are heated up by solar energy, she explained, and in suitable conditions, heat trapped under the plastic yields temperatures hot enough to kill pests, weeds and some plant pathogens, too.
Solarization is most effective during the sunniest weeks close to the summer solstice, but it can also be effective in spring and later summer. Even in Maine in May, maximum soil temperatures beneath the clear plastic in Dr. Birthisel’s plots were typically around 100 degrees — “or sometimes as hot as 118.” After two weeks, she said, that “was effective for pretty substantive weed control.”
Her research in support of farmers is conducted on open fields, but she has advice for gardeners, too.
“If you wanted to take a piece of lawn and turn that into a garden, solarization would be a great first step,” Dr. Birthisel told me in an interview last year. “If you lay that down for several weeks, it’s going to do quite a number on your grass.”
Sonja Birthisel’s Solarization Tips
Solarization is more effective when soil is moist. Irrigate or wait until just after a rain to install the plastic.
To better trap heat, patch any holes and tightly secure plastic edges by burying them or weighting them down all around.
Avoid bringing fresh weed seeds to the surface by minimizing soil disturbance between plastic removal and planting.
When you are solarizing open soil, try incorporating compost before solarization. Many studies suggest this can increase pest control.
Controlling perennial weeds will likely require far more than two weeks of solarization.
More about Traditional Soil Preparation
If you’re interested in learning more about more traditional soil-preparation methods, John Jeavons’s classic book “How to Grow More Vegetables” has continued to be updated over the decades, and his YouTube channel has a seven-video series on his “biointensive method,” including a how-to on double-digging in the first installment.
The influential gardener and educator Alan Chadwick, who died in 1980, developed a “biodynamic French intensive method” that calls for turning and mounding up the soil, as shown in this video.