How to Grow Lettuce in a Rain Gutter

Whether you're the type who loves plain green lettuce (Lactuca sativa) or you crave a "mesclun" mix of many varieties and colors, one thing's sure: the greens you grow at home are going to be packed with nutrition and flavor -- and far more of it than you'll get from the supermarket, says the Old Farmer's Almanac. Whether space is limited or you're just looking for a way to adorn a blank exterior wall, a rain gutter will provide ample space for lettuce. Just be sure to give consider the drainage, soil and nutrients that are best for this unique form of container gardening.

If you're buying new rain gutters, they'll tend to be made from aluminum, steel or vinyl, which can be safe for growing. Nearly any container can be used for container gardening, suggests Colorado State University Extension, so long as it hasn't contained any toxic substances. If you're using recycled gutters, check for lead paint on the inside or outside of the gutters. Houses were painted with this potentially toxic substance before the 1970s -- something you definitely don't want close to containers where you're growing food. If you see any old paint, put on a pair of gloves and a mask and remove a small chip of the paint. Then have it tested with your state or local environmental services office. If the gutters contain lead, don't use them.

If you're using recycled containers, prepare a mixture of 1 part bleach to 9 parts water and wipe down the insides with a cleaning brush soaked in the solution. Then rinse with water. All container gardens need drainage holes, and lettuce in particular likes a well-drained soil. Along the bottom of your gutters, drill a 1/4-inch hole every 4 to 6 inches. Before you add soil, secure the gutters to a wall or put them where you plan to keep them, as they'll be too heavy to move with soil inside. Different gutters have differing requirements for mounting, but to handle the added weight of the soil, a crossbar hanging system can work well. That method clips a hanger to the front of the gutter, crosses over top, and then secures to a bracket -- which you mount on the wall -- at the back.

Container gardens tend to dry out much more quickly than in-ground gardens, which means you'll have to water them more often. It also means that the nutrients you add to the gutters will leach out faster. Lettuce likes a loose, loamy, sandy soil, so create a potting mixture of one-fourth garden soil, one-fourth coarse sand, one-fourth compost and one-fourth perlite or vermiculite. Also mix in some granules of slow-release fertilizer. For every 100 square feet, the University of Georgia Cooperative Extension recommends adding 3 or 4 pounds of 5-10-10 fertilizer -- meaning it will have 5 parts nitrogen and 10 parts phosphorous and potassium. (see reference 7)

Sow your lettuce seeds about 1/2 inch from the top of soil. For leafy types of lettuce, The Old Farmer's Almanac recommends planting seeds 4 inches apart. For loose-head types, plant seeds 8 inches from each other, and for head types, plant them 16 inches apart. If you want to have a continual harvest, plant more seeds every two weeks in the early spring as well as late summer and fall, and harvest your greens when the leaves are at least a few inches long. As you trim off leaves, more leaves will grow. Because you're growing in relatively shallow containers, water frequently -- perhaps even twice a day during the warmer months.