How to Grow Turnips & Tomatoes Together

Start the amendment process in early spring, two to three weeks before the last scheduled frost. Turnip seeds germinate at 40 degrees F, and the vegetables do best with cool springtime growing seasons.

Clear weeds and rocks from a large site with full sunshine, good drainage and air movement. Plan to put tomatoes and turnips in the same site; turnips grow to harvest quickly, and won't interfere with ultimate tomato growth.

Amend the soil to a depth of 10 to 12 inches for these vegetables, which require deep, loose and nutritious soil. Turn 6 inches of organic compost into the natural soil and add 6-24-24 or 8-32-16 -- the numbers indicate the percentages of nitrogen, phosphorus and potassium in the product -- fertilizer for rooting.

Plant turnip seeds 1/2 inch deep, with up to 20 seeds per foot of planting. Leave 12 to 24 inches between multiple rows. Lay 2 inches of mulch over unplanted soil to keep it moist and warm, and water the turnips with 2 inches of water every week.

Thin the turnip seedlings to every 2 to 4 inches in the row when they sprout, to give them more room for growth. Use the foliage as greens in salads or on sandwiches.

Plant tomato seeds or seedlings when nighttime temperatures reach 65 degrees F. Put the tomatoes between the established turnip plants, at 24 to 36 inches in the row. Leave 4 to 5 feet between tomato rows. Put the tomatoes on the same watering schedule as the turnips, and renew the mulch layer.

Harvest turnips when they reach 2 to 3 inches in size. Pull the plants up to access the root vegetables. Put stakes or trellis systems up behind the remaining tomato plants, and tie the plants to the structures with cord ties.