Guide to Interplanting and Intercropping in the Garden

Interplanting is a gardening word that encompasses several organic practices each with specific goals. In its simplest form, interplanting means growing two or more different kinds of plants in the same bed or garden area. The overall goal is to use the space to greatest efficiency while growing healthy plants and increasing the harvest, or adding color and texture to flowerbeds.

How Does Interplanting Work?

Benefits realized by interplanting vary depending on the method chosen. Plants with deep roots may be grown with shallow rooted plants avoiding competition for soil space. A crop that requires pollination may be grown with flowers or other vegetable varieties that attract pollinators. By the same token, different varieties may attract pests and help to control damage to other plants in the garden. Tall plants like corn serve as support for vining plants like pole beans and tomatoes can provide shade for sun-sensitive crops like lettuce. Crops and flowers grown closely together tamp down weedy growth in the garden.

Important considerations for effective intercropping require combining plants with synergistic relationships that do not compete for space, nutrients, water, and sun, Heavy feeders like cabbage and cauliflower thrive when planted alongside beans which are nitrogen fixers that add nutrients to the soil. Interplanting the same crop with another heavy feeder such as sweet peppers can deplete soil nutrients and result in a smaller harvest from both plants. Carrots do best in drier soil so planting them alongside tomatoes, which require plenty of water, is a good choice. The carrots also aerate the soil allowing a better flow of water and nutrients to the tomatoes. Crops harvested at different times give the gardener double use of space as long as the crops are planted at the ideal times for the combinations to work. A good example is sowing radish and carrot seed in a bed or row. Radishes sprout quickly, marking the carrots which take longer to germinate. By the time the carrots need soil space and nutrients to grow, the radish has been harvested.

Intercropping Methods

Intercropping techniques often have some overlap so try not to get caught up in terminology. The goal is to create combinations for garden health, increase, and beauty.

Companion Planting

This method puts two or more different varieties of plants together with each receiving some benefit from the other.

• Plant marigolds with tomatoes. The scent of marigolds repels tomato pests.
• Interplant rows of beans or peas between rows of peppers or tomatoes. The beans replace nitrogen in the soil used up by the heavy-feeding tomatoes and peppers.
• In the classic Three Sisters combination, plant corn, beans and squash in hills. The corn supports the vining beans and large squash leaves shade shallow corn roots.
• Plant zinnias and sunflowers in the vegetable garden and clover in the orchard to attract pollinators and provide shelter for insect predators.
• Flower garden combinations are endless. Mix plants for color, height, texture and seasonal bloom.

Succession Sowing

Sowing seeds or transplants together that are harvested at different times is a form of succession sowing. Another form is to replant a row or bed of early harvested crop with a second crop of the same or different crop entirely. Succession sowing can be used to facilitate crop rotation; a basic principle of successful vegetable gardening.

• Early crops like lettuce, beets, and kale crops which include cabbage and broccoli can be planted every two weeks in spring to extend the harvest.
• When the temperatures warm up, replace the lettuce bed with summer squashes. Once they are up their broad leaves can even provide shade for a late summer or early fall lettuce crop.
• Use the space available after harvesting onions and early potatoes to plant a row of beans or winter squash.
  

Trap Cropping

The goal of trap cropping, common in French intensive gardening, is to attract pests of one crop to a different crop that can better tolerate any damage.

Japanese beetles love okra leaves and corn silks. These pests are the reason kernels don't develop uniformly on an ear of corn. Each individual silk has to be pollinated from the tassel for a kernel to grow so if the silk has been consumed, the ear is spotty. Japanese beetles eat the leaves of okra which has little to no impact on the fruit or the overall health of the plant. Planting a row of okra next to or near the corn crop helps prevent beetle damage.

Develop a Gardening Layout and Schedule

Interplanting is an intensive form of gardening that usually requires some trial and error. There are lots of books and websites that offer suggestions for good combinations and also what to avoid. The greatest success requires planning ahead and using a calendar and garden layout to help guide your efforts.

All garden plants need nutrients, sun, water and space. Learn and think about the specific requirements of the varieties you want to grow and create a workable chart. Keep notes about the success or any problems that occur with the combinations you choose.

Look at the growth rate to work out a plan for succession sowing. Vegetables that root deeply like carrots, tomatoes, and parsnips go well with shallow veggies like lettuce, broccoli, and potatoes. A fast-growing ground cover adds more interest than just mulch in a seasonal flower garden.

Shade is another factor to consider. Tall and broad-leaf crops can grow lettuce, spinach or celery underneath. Alternate spring, summer, and autumn crops and flowers to extend the harvest with seasonal vegetables and keep the flower garden blooming.