Companion planting maps for raised beds in Chicago clay soil, optimizing pest control and rotation

For a standard two-bed (4x8 ft) system, this three-year rotation plan minimizes pest and disease buildup while improving soil health above the native Chicago clay. Before filling beds, ensure good drainage by layering cardboard at the bottom, followed by a mix of 60% compost and 40% topsoil/peat moss to counteract the poor drainage of the underlying clay. A common beginner mistake is using only bagged garden soil, which can compact heavily, or not filling the bed high enough—it will settle several inches. Fill to the brim. The cardboard smothers underlying grass and weeds without plastic and slowly decomposes. Use plain brown cardboard with all tape removed.

YEAR 1 ROTATION

Bed A: The Tomato & Pepper Family (Heavy Feeders). Plant 4-5 indeterminate tomato plants down the center, spaced about 24 inches apart for good airflow, a key to preventing blight in humid summers. Intersperse 4-5 pepper plants between them. Plant a dense border of basil and French marigolds around the entire bed. Basil can help repel tomato hornworms, while marigolds deter nematodes in the soil. Borage is another excellent companion, attracting pollinators for better fruit set. A common mistake is overcrowding, which invites disease. Prune the lower "sucker" stems of your tomatoes to force energy into fruit production and further improve air circulation. Troubleshooting: If leaves turn yellow from the bottom up, it could be a nitrogen deficiency or overwatering. Check soil moisture by inserting a finger two inches deep. If it's dry, water deeply at the base of the plant in the morning to avoid wetting the leaves.

Bed B: The Root, Leaf & Legume Mix. This bed focuses on lighter feeders and soil builders. Plant two rows of bush beans down one long side. Beans are legumes and fix nitrogen in the soil, which will benefit next year's heavy feeders. In the remaining space, interplant rows of carrots, radishes, and leaf lettuce. The feathery carrot tops won't shade the lettuce much. Radishes mature quickly and can be harvested before the other plants need the space, a technique called succession planting. A border of chives or onions can help deter aphids from your lettuce. A great trap crop for aphids is nasturtium; plant a few in the corners to lure aphids away from your greens. Troubleshooting: Tiny "shot holes" in radish or kale leaves are likely from flea beetles. The best non-chemical defense is to cover the bed with a lightweight floating row cover immediately after seeding to create a physical barrier.

YEAR 2 ROTATION

Bed A: The Root, Leaf & Legume Mix. The beans you plant here will replenish the nitrogen that last year's tomatoes heavily consumed. Follow the same layout as Bed B in Year 1. This rotation starves out any soil-borne tomato diseases (like blight spores) that may have overwintered.

Bed B: The Tomato & Pepper Family. This bed, having been enriched by last year's beans, is now primed for the heavy-feeding tomatoes and peppers. Follow the same companion planting layout as Bed A in Year 1.

YEAR 3 ROTATION

Bed A: The Brassica & Allium Family. This year, introduce a different plant family to confuse pests.