It can be a fascinating project to plan the layout for an intercropped garden. The "three sisters" crops -- corn, beans and squash -- are the classic example of intercropping garden vegetables. Peoples indigenous to the Americas have partnered these three crops for thousands of years. The beans use the tall corn to climb upon and the squash sprawls out beneath the two on the ground, shading roots. The taller plants shade the squash. Intercropping solves the problem of limited space in the home garden. The successive planting involved in intercropping means something is usually ready to harvest.
Intercropping creates a garden where plants are interdependent and mutually helpful. Plan an intercropped garden with consideration of how to maximise cooperation and decrease competition among plants. The four variables when pairing vegetables are spatial relations, the density of foliage and roots, the height and shape of plants and how long they take to mature. The garden will be safer from pests and disease because the invaders will find limited amounts of their favourite foods in one place. At the same time, the plan provides good conditions for useful garden visitors like worms and beneficial bacteria.
The plan you devise for your interplanted garden will be specific to your space, climate and vegetable preference. Start with a list of vegetables you like and want to grow. Find out the best time to plant each one. Find out how long each one takes to grow, how large it gets and how deep its roots are. Make a shorter list of the vegetables that can be planted first. Start by planting the largest and slowest growing of those. Next to it plant a shorter and faster growing plant. Think through each choice before you plant. Avoid competition among plants for sun, stretching space and room for root growth.
Size and Height
Foliage types and sizes vary widely among vegetables. Some grow to 6 feet or more and others scarcely rise above the ground. Large-leafed cabbage takes up a lot more space than broccoli, which has smaller leaves and grows higher. These are a good intercropping pair. Pumpkins not only spread out on the ground, but have large fruit. Summer squash trained over small cages would be a companion for the pumpkin. Grow anything that can climb, such as tomatoes, cucumbers, beans and peas, on stakes or trellises to save space. Their foliage provides wind and sun shelter for ground crops.
Have an idea of how large and deep the roots are of everything you plant to avoid competition underground. Some root vegetables, like beets and turnips, take up a lot of space, but carrots and radishes much less. Don't crowd root vegetables together. Pair them with plants that have shallow roots but won't get overshadowed by their foliage. Brussels sprouts interplanted with beets is a good coupling. The rule of thumb is to not plant vegetables together that feed at the same root depth.
A scheme for planting that accounts for plant maturation time might look like this: Plant peas, radishes and carrot seeds at the same time. Radishes germinate and grow quickly. They mark the rows of the carrots that take much longer to germinate and mature. The peas grow more slowly than the radishes but are gone by the time the carrots are up. Radishes are harvested as the carrots are just getting established. When the peas are spent, put tomato plants in their place or put in a stake for beans to climb