Companion Plants for Romaine

Shady Companions

• Romaine thrives best in light shade, which maintains cool growing conditions. Sunlight nourishes young romaine plants during their early growth period while surrounding plants' expanding foliage protects the crop as the weather heats up in later spring and early summer. Romaine grows well under the protective canopy of common sunflowers (Helianthus annuus), tomatoes (Lycopersicon esculentum) and eggplant (Solanum melongena).

Long-Growing Companions

• Depending on the variety, romaine grows to maturity in 55 to 80 days, according to an article in Master Gardener Journal, a publication of Maricopa County, Arizona, Master Gardeners. Romaine needs to be harvested before the arrival of warm weather, which causes it to bolt quickly. The early harvest leaves the ground empty for later-maturing plant companions to spread. Long-growing crops that perform well with romaine include beans (Phaseolus vulgaris), squash (Cucurbita maxima, Cucurbita moschata and Cucurbita pepo) and dill (Anethum graveolens). Strawberries (Fragaria), hardy in U.S. Department of Agriculture (USDA) plant hardiness zones 3 through 10, also grow amicably with romaine.

Pest-Control Companions

• Interplanting romaine with certain trap crops can be a natural form of pest control. If aphids are a problem in your growing area, then planting alyssum (Lobularia maritima) as neighbors of romaine will attract syrphid adults to lay eggs on the romaine, where the larvae will use the aphids as a food source. Chives (Allium schoenoprasum), which are hardy in USDA zones 3 through 10, and garlic (Allium sativum), hardy in USDA zones 3 through 8, also discourage aphids from moving into a romaine patch when they are planted nearby.

Unwelcome Companions

• Although vegetables in the mustard and goosefoot family, such as brussels sprouts (Brassica oleracea gemmifera), beets (Beta vulgaris), broccoli (Brassica oleracea, Italica group) and radish (Raphanus sativus) are often recommended as good lettuce companions, such crops sometimes encourage an aphid infestation, according to an article on the U.S. Department of Agriculture Regional Integrated Pest Management Centers Information System website. So if your garden has chronic problems with aphids, avoid planting those crops to prevent an infestation. Whiteflies also can be a problem for lettuce planted near alfalfa (Medicago sativa) and cotton (Gossypium spp.). Avoiding pest-attracting companion plants can encourage whiteflies to find another food source. Cabbage (Brassica oleracea var. capitata) has a negative effect on romaine's growth and flavor, according to the Golden Harvest Organics website. Keep romaine and cabbage plants separate for the best results.