French intensive gardening reached a peak in the late 1800s and early 1900s, by which time it had also reached England. It was introduced in the United States by the English gardener Alan Chadwick who started a French intensive garden at UC Santa Cruz in 1967.
Key Principles of French Intensive Gardening
Many principles of French intensive gardening are standard gardening practices today, especially for small urban spaces. You do not need to apply all the elements of French intensive gardening at once; you can pick and choose those those that work for your space. However, the most important consideration when using French intensive gardening is soil preparation.
Soil Improvement
To obtain well-drained and well-aerated fertile soil, French intensive gardening uses deep digging by hand. This can either be single digging to a depth of 12 to 15 inches, or double digging up to two feet deep, breaking up the top layers of the soil and replacing them with soil amended with fine, well-matured compost. While this is physically demanding, the goal is to break up the soil deeply, allowing roots to grow vertically instead of competing with neighboring plants for nutrients. Amending the soil with mature compost helps improve both the soil’s composition and adds nutrients the plants require to thrive.
Raised Beds
In French intensive gardening, avoiding soil compaction is one of the main ideas behind the garden. Some growers use raised beds to ensure that there is no stepping on the vegetable beds, and no valuable space is wasted. However, the raised beds need to be quite tall to achieve the depth necessary for intensive planting, allowing the plants’ roots to grow vertically. Instead, preparing garden beds that are not too wide to ensure the gardener can reach into the middle of the bed without stepping on the bed and compacting the soil may be a better choice. Most beds are designed no greater than four feet wide, allowing easy access to the center of the bed for planting, weeding, and harvesting without stepping on the soil.
Close Spacing
Crops are planted two to five times tighter than in traditional vegetable gardening, and there is little to no bare soil. For example, onions that are typically spaced six to eight inches apart in either direction are spaced three inches apart. This produces higher yields, but only if the soil has been amply amended with compost beforehand, and the roots of the plants can grow vertically instead of horizontally, or else neighboring plants will constrict each other. Vertical root growth is only made possible if the deeper layers of soil are not hard and encrusted, hence why deep digging is required. The two other benefits of close spacing are that weeds don’t get much of a chance to grow, and just like mulch, it reduces the loss of soil moisture through evaporation.
Companion Planting
What is usually called companion planting today is also known as intercropping in French intensive gardening. Crops that happily coexist because they don’t hamper each other’s growth are interplanted at the same time. The best matches are often opposites: slow- and fast-growing plants (like lettuce and radishes), tall and short plants (beans and lettuce), deep- and shallow-rooted (parsnips and arugula), and heavy and light feeders (broccoli and peas). Or tall plants can cast a shade on crops that need protection from the hot summer sun, such as corn or pole beans shading lettuce. Another variation of companion planting is relay cropping where a second vegetable is seeded in-between the plants of a first vegetable that was either planted much earlier or takes much longer to mature. By the time the second vegetable reaches it full size, the first one is already harvested. A classic example for this is intercropping radishes with carrots. Radishes sprout and mature quickly and can be harvested within three to five weeks after seeding. By the time the carrots are ready to harvest 70 to 80 days after seeding, the radishes are long gone.
Succession Planting
Transplanting seedlings takes precedence over direct seeding in the soil when succession planting. The only exception is root vegetables, because they do not transplant well. Again, saving space is the guiding principle here. When you transplant a healthy lettuce seedling into a raised bed, the likelihood of it growing into a full head of lettuce is much higher than when you direct seed many lettuce seeds. Germination rates may be erratic, and you may have big gaps in your row of lettuce. Also, a transplant is much more apt to compete with weeds than tiny seedlings that are just emerging from the soil. The drawback is that growing transplants requires quite a setup—a space such as a planting table, or a greenhouse or cold frame if you want to get a head start on the growing season—as well as knowledge about the growth patterns of the different vegetables and good planning so that your transplants are ready when you need them.
Crop Rotation
This is a must for all gardens to promote soil health, maintain nutrient balance in the soil, and for pest and disease control. While the requirements for crop rotation—planning and record-keeping—are the same for all gardens, crop rotation can be more challenging in French intensive gardening because you have less space to move crops around.
