Growing lettuce with certain companion plants can help control the leaf eating pests and the plant diseases they are host to.
Lettuce is a relatively easy plant to grow, but it does attract a number of garden pests that will devour your crop. Some of these pests are also known to carry plant and soil borne diseases that can cause long term problems in the vegetable garden. Companion planting, proper planting methods and maintenance are natural ways to prevent and control some of these problems without having to use pesticide and fungicide applications.
Lettuce requires well-drained soil. Amend the soil with compost or well rotted manure before planting. Check the drainage before you seed. If water collects and stands on top of the soil for more than a minute, the soil needs more structure to allow for drainage. Building up a slight, south-facing slope can also help with drainage problems. Add one pound of compost or manure per square foot of soil, working it 6 inches into the soil. Wait 10 to 14 days before planting your lettuce. This wait period will give the manure time to nitrify in the soil and release its nutrients while building up the structure of the soil.
To prevent and manage pest and disease problems, choose plants that are compatible with lettuce and that help repel garden pests or attract beneficial insects. Bringing in the good bugs before you sow the lettuce seed will give the new seedlings a better shot at survival.
Some of the most common garden pests that will attack lettuce are cut worms, cabbage worms, loopers, aphids, and army worms. Plants that repel certain insects are an important step in the planting process as well.
To give your lettuce a fighting chance, put a few of these plants into the garden before you sow the lettuce seed.
Sweet alyssum attracts insects that eat the larvae of cut worms. Cut worms are a threat to new seedlings. They will chew through the stem of new lettuce plants and leave the leafy green top lying on the soil.
Sage repels cabbage loopers and cabbage worms. While they are known to attack cabbage, broccoli and cauliflower, they also love to munch on salad greens.
Rosemary repels cabbage moths, as does thyme and sage. The cabbage moths are small, white moths many mistake for butterflies. While they may be delightful to watch, be alarmed if you are growing a garden. If the moths are present, so are their eggs and larvae.
Onion family. Onions, scallions and garlic will repel slugs and snails.
Amaranthus is a beautiful flowering annual that attracts ground beetles that dine on slugs and snails.
French marigolds repel aphids and cabbage moths as well as attract many beneficial insects.
Interplanting is important in the companion garden. It differs from the traditional, monoculture row garden with long stretches of lettuce all planted together. Traditional row gardens are invitations for pest infestations. The volume of a particular food is like an all-you-can-eat buffet for offending garden pests. Companion planting, however, uses interplanting methods to control and limit pest infestations and garden diseases.
Plant a small section of lettuce in between scallions or garlic. Put in a perennial herb like sage or rosemary that repels pests. Make sure you have flowers. The alyssum, marigold and amaranthus will add beautiful color and interest while they are protecting your salad garden.
Include other crops that are compatible with lettuce. Tomatoes are helpful for growing lettuce, especially in the hotter months because they provide shade and shelter from the hot sun. Carrots, radishes, strawberries and cucumbers are also very friendly with lettuce.
Keep the soil moist, but not wet. Soil that does not drain well, or is too wet will invite fungal problems and other diseases in the garden. It is also important to keep the lettuce weeded. Weeds are breeding grounds for plant diseases and pest populations.
Rotate crops to different sections in the garden each season for more pest protection. Follow a rotation schedule in your garden and keep track of it with a garden journal.
Photo: Forest & Kim Starr [CC-BY-3.0 (www.creativecommons.org/licenses/by/3.0)], via Wikimedia Commons