Can Garlic Be Grown Next to Rhubarb?

They Have So Much in Common

• Garlic (Allium sativum) and rhubarb (Rheum x hybridum) are perennial plants. Garlic is hardy in U.S. Department of Agriculture plant hardiness zones 4 to 9, while rhubarb is hardy in USDA zones 3 to 8. They both grow in sunny gardens with over six hours of direct sunlight each day, although rhubarb can be grown in partial or bright shade. Organically rich soil with a pH of 5.5 to 6.8 is ideal for both, although rhubarb can be grown in soil with a pH as low as 5.0.

Their Differences Can Be Overcome

• For best flavor, rhubarb requires moist soil that is never allowed to dry out. Garlic requires moist soil but only until about midsummer. From midsummer through harvest time the soil should be allowed to dry before watering. Watering the rhubarb right around the base of its stems will keep the soil around the garlic’s shallow roots dry enough near the end of the summer. Well-aged manure or compost should be added to the soil in the spring and fall for both rhubarb and garlic, but rhubarb requires a little extra compost in the middle of summer. It can be spread over the soil right next to the rhubarb stems, though, so it will not affect the garlic. Rhubarb does not actually do anything for garlic, but garlic repels carrot root flies, codling moths, snails, root maggots and Japanese beetles. It also acts as a natural fungicide, which is generally beneficial to the entire garden.

Give Them Their Space

• Rhubarb root sets are planted in the spring four to six weeks before the last expected hard frost. Garlic bulblets or cloves are planted at the same time as rhubarb in the spring or in early fall. Garlic planted in the fall will have larger bulbs at harvest time than when planted in the spring. Plant multiple rhubarb sets 3 to 4 feet apart and multiple garlic bulblets or cloves 6 inches apart. Do not plant garlic any closer than 3 to 4 feet from the rhubarb. If it is planted any closer, the rhubarb leaves will shade the garlic. Cover the garlic bulblets or cloves with 2 to 3 inches of straw during the winter.

Encourage Productivity and Reap the Rewards

• Flowers must be removed from both garlic and rhubarb as soon as they appear to force the plant’s energy into bulb and stem formation. Also remove the seed stalks from the rhubarb. Harvest the garlic bulbs in late summer when the leaves turn brown and begin to collapse. “Lodging” or bending the tops of the stems to the ground when they begin to turn yellow encourages better bulb structure. Rhubarb stalks are not harvested until the second year after planting. Harvest the outer stalks after they reach 2 feet tall and the plant is 3 feet wide. Never take more than one-third of the stalks each year.