Japanese vegetable gardening emphasizes harmony with the environment for extraordinary vegetable production, combining ancient methods with high-tech garden innovation.
All over the world people are attracted to Japanese ornamental gardens because they create a tranquil environment, emulating the natural world at its most serene with a minimal use of plants, water, and stone. Japanese vegetable gardens also make economical use of materials and create a calming vibe, but achieve astonishing productivity with methods many gardeners have never considered.
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Raised Rows Instead of Raised Beds
Raised bed gardening is a well-known technique. Three-foot wide plots are dug deep and worked to a fine tilth. Then they are heavily fertilized and densely planted, never trod upon, for yields much greater than traditional row gardening.
Japanese vegetable gardeners sometimes use raised beds, especially in the rainier sections of the island of Kyushu. In much of the rest of Japan, however, the challenge of summer vegetable gardening is that the growing season begins wet and ends dry. Plants need drainage for germination and early growth, but irrigation to complete the harvest.
Gardening with Rows of Raised Earth
The Japanese solution to this problem is to grow vegetables in rows of earth piled about 6 inches (15 cm) high. In the spring rainy season, seedlings get good drainage that reduces the risk of damping off and other fungal diseases. In the late summer, as the soil dries out, furrow irrigation brings water to the plant’s roots without splashing that can spread bacteria and fungi that injure the crop. The furrows deliver water without spraying or splashing exactly where mature vegetables need it.
Related: Best Manure for Vegetable Gardening
Creative Use of Trellises
If you visit a Japanese vegetable garden in early spring, you will probably see several rows of bamboo or plastic espaliers. These won’t be trellises designed for dwarf plants. Each espalier will stand 6 to even 8 feet (150 to 200 cm) tall, carefully tied to support as much as 100 pounds (about 50 kilos) of plant weight.
These aren’t structures exclusively for roses or fruit trees. They are supports for tomatoes, eggplants, cucumbers, and pole beans, along with more traditional crops. These crops are trained to grow flat against a wall.
When frost has passed, a typical Japanese gardener sets out transplants under the latticework, each plant in about 40 liters (10 gallons) of its own soil. When a row is about a foot (30 cm) wide and about 6 inches (15 cm) high, transplants can be set about a foot (30 cm) apart. There should be at least two vertical poles between every two transplants, with no transplants next to it.
Each transplant is set out next to a horizontal member of the espalier. When it grows tall enough to reach the first crossbar, one of its stems is stretched horizontally. When the stem grows out to the next vertical pole, it is tied to the pole, so the plant has a stem growing upright parallel to the transplant.
Growing up and out along the espalier ensures that each plant gets as much sun as possible and as much air circulation as possible. Vertical growth, rather than horizontal growth, makes inspection for insects and diseases easier. And Japanese gardeners regularly report growing hundreds of tomatoes or eggplants on a single plant, growing from just 2 square feet (0.2 square meters) of ground.
Traditional Japanese farmers and gardeners use two unique tools with their raised rows of vegetables, the Hori Hori knife and Triangle hoes. Colorado State University has excellent information on these tools here.
Stimulating Plant Growth with Color
Japanese vegetable gardeners use color in a way that would never occur to formal garden landscapers. Modern Japanese vegetable gardeners use plastic to filter sunlight to concentrate the frequencies that stimulate growth and fruiting.
Increasing vegetable production with red and blue light is literally a science. Only certain wavelengths of sunlight, red, green, yellow, and blue, have enough energy to power photosynthesis. Other wavelengths don’t provide energy for photosynthesis, but do have enough energy to create free radicals that can injure the plant. (Many of the beneficial plant chemicals in vegetables and fruit serve the role of free radical fighter in the plant.)
Clear and colored plastic mulches let rainfall reach the soil beneath them while reflecting colored light up to the plants above them. Japanese horticulturalists have observed that:
Clear plastic mulch is durable and warms the soil in the spring, but doesn’t help with weed control. Silver plastic mulch stimulates growth of vines. It accelerates the growth of the leaf mass melons need for photosynthesis for extra-flavorful fruit.
Plastic mulch that is white on one side and black on the other, is very useful for starting plants in the late summer. If the mulch is put out white side up and black side down, the white side reflects sunlight and lowers soil temperature while the black side blocks sunlight and stops the growth of weeds.
Red mulches help plants like strawberries and watermelons make more sugar so they taste sweeter when they are ripe.
Mulches of any kind retain late-season soil moisture that makes slowly ripening fruits darker and sweeter.
Thanks to Japanese innovation, there are now colored plastic mulches made from cornstarch. These mulches stop weed growth, keep the soil moist, and stimulate plant growth throughout the growing season, but they break down after a few months. There is no need to gather the mulch every fall and find a place to dispose of it. With this Japanese innovation, all that is necessary is to till the mulch back into the soil, where it becomes compost.
Respect Every Plant
Related: The many benefits of raised bed gardening
Japanese gardeners are famous for finding exactly the right spot in their gardens for each crop. Since a simple meal in Japan often includes dozens of different plant foods, optimizing growing spaces is important not just for productivity but also for the variety that makes Japanese cuisine so enticing.
While most Japanese gardeners have a flair for framing crops into beautiful squares and for using natural elements to bring some of the same beauty to their vegetable gardens that they bring to their ornamental gardens, the Japanese principles for vegetable planting are more about higher yields.
Use espaliers to provide shade for delicate plants. Set out shade-loving plants on the side of the espalier that receives the least sun.
Place drought-tolerant plants at the end of the row farthest from the water source. These plants need some furrow irrigation, but not as much as the plants at the other end of the row.
Place specialty plants where they are easy to harvest just before they are needed for cooking. If you plant shiso mint or shishito peppers, for instance, keep them in a smaller herb garden and give them more intensive attention.
Be kind to the birds and the bees. Give them flowers at the margins of your garden to they will stop for refreshment and repay you by pollinating your plants. Leave some plants outside your garden for shelter and as a home for the insects that also feed your birds.
Japanese vegetable gardens have a beauty of their own. Try these simple innovations, and see the vibrant difference that Japanese vegetable gardening techniques make in your own vegetable garden.