Can Salad Greens Be Grown Indoors?

Containers

• Container size depends on the expected mature size of your salad greens. Small, leaf lettuce varieties grow best indoors because they take up minimal room. They also tolerate repeat harvesting, which allows the plant to produce over a longer time period. A single plant can grow in a container as small as 6 inches in diameter. A larger container or tub, up to 12 to 18 inches in size, allows you to grow multiple plants but is still compact enough to light properly. Use containers that provide at least 8 inches of soil depth. Purchase containers with bottom drainage holes or drill holes in the bottom of the container.

Soil and Fertilizer

• Purchased potting soils provide a suitable growing medium for salad greens, or you can make your own potting soil by combining equal parts peat, compost and perlite. Avoid garden soil as it compacts in the pots and provides poor aeration and drainage. Purchased soils that contain fertilizer don't require additional fertilization for six to eight weeks, but homemade and unfertilized mixes require fertilization from the time the seeds sprout until the final harvest. Use a soluble balanced fertilizer every two weeks, using the application rate recommended on the package for your pot size and the application frequency.

Planting Greens

• Plant either purchased seedlings or seeds. If you choose seedlings, plant them at the same depth in the pot they were growing at in their previous container. Sow seeds on the soil surface and cover them with a 1/8 inch layer of moistened soil. Lettuce and other greens typically germinate within a week of planting. Spacing in larger containers depends on the particular green variety. Generally, a spacing of 4 to 6 inches between small lettuce plants provides sufficient room.

Irrigation

• Proper watering ensures the greens grow and produce an abundant crop without suffering from fungal or drought problems. Too much moisture in the soil causes sogginess. In a cooler indoor environment this can lead to mildew, mold and other fungal growth. Allowing the soil to dry completely before watering stresses the plants and eventually leads to poor production or death. Water only when the soil surface feels dry but before the soil dries out completely.

Light

• Although many greens can tolerate partially shaded areas outdoors, indoors they require all-day sunlight. Use fluorescent grow lights instead of depending on a window to provide enough light. Set the plants so the tops are 6 inches beneath the light and leave the light on for 14 to 16 hours a day. Simplify the lighting process by plugging the fixture into an automatic timer that turns the lights on and off at the same times daily.