The harvest of garlic, typically occurring in early to mid-summer, creates a unique opportunity for gardeners to maximize space and double their seasonal yield. This practice, known as succession planting, involves immediately planting a second crop in the vacated space for a continuous harvest well into the fall. Garlic requires a long growing season, so its removal leaves a prime window of approximately 60 to 90 days before the first expected frost. Utilizing this mid-season gap allows for a full fall crop, but requires careful consideration of soil health and timing.
Why Crop Rotation is Essential After Alliums
Planting a different family of vegetable after garlic is necessary to protect the health of the soil and the subsequent crop. Garlic, a member of the Allium family, is a heavy feeder that draws substantial amounts of specific nutrients, particularly nitrogen, to support its leaf and stem growth. This nutrient depletion means the bed is not immediately ready for another heavy-feeding crop.
The primary reason for rotation is to disrupt the life cycle of soil-borne pathogens and pests specific to alliums. Diseases like white rot and Fusarium basal rot can persist in the soil for years, and planting another allium, such as an onion or leek, would guarantee infection. Pests like the onion maggot or garlic bloat nematode also target alliums, and rotational planting breaks this cycle, reducing their population. Avoid planting any allium in the same spot for at least three to four years to allow these pathogens to die off.
Recommended Crop Families for Succession Planting
The best choice for a second crop is a plant family with a different nutrient profile and vulnerability to allium-specific pests and diseases.
Legumes
Legumes, including bush beans and peas, are excellent rotational partners because they have a symbiotic relationship with nitrogen-fixing bacteria in their root nodules. These bacteria convert atmospheric nitrogen into a usable form, replenishing the nitrogen supply consumed by the garlic. Bush beans are often preferred over pole beans for succession planting due to their shorter days to maturity and faster, concentrated harvest.
Leafy Greens and Brassicas
Fast-growing leafy greens and brassicas thrive in the cooler temperatures of late summer and fall, making them ideal candidates. Crops like kale, Swiss chard, fast-maturing cabbage varieties, and spinach grow quickly and have different nutrient needs than alliums. Many of these cool-weather crops can withstand a light frost, extending the harvest past the end of the growing season.
Root Crops
Non-allium root crops are also a good option because they draw nutrients from different soil depths than the garlic. Carrots, beets, and radishes are excellent choices. Radishes offer the quickest turn-around, sometimes maturing in as little as 30 days. When selecting any of these crops, choosing “early” or “fast-maturing” varieties helps ensure a successful harvest before the hard frost arrives.
Preparing the Bed for the Next Harvest
The transition between the garlic harvest and the next planting requires deliberate soil preparation to ensure the second crop’s success. Immediately after digging up the garlic, remove all residual plant debris, including old bulbs, roots, and weeds. This step prevents the carry-over of lingering diseases or pests into the next crop.
Garlic’s root system can sometimes compact the soil, so gently loosening and aerating the bed with a digging fork will improve drainage and create a favorable environment for new root growth. The depleted nitrogen must be addressed by incorporating a rich organic amendment into the top few inches of the soil. Spread a few inches of well-aged compost, manure, or a balanced organic fertilizer across the bed and mix it in before planting.
Timing Your Second Planting for Fall Success
Successful succession planting relies on precise timing, determined by the specific climate of the garden. Gardeners must calculate the planting date backward from their region’s average first frost date to ensure the fall crop has enough time to reach maturity. This calculation involves adding the crop’s “Days to Maturity” (DTM) to a “fall factor” of about two weeks, which accounts for slower growth rates due to declining daylight and cooler temperatures.
Since garlic is often harvested during mid-summer heat, the initial planting window is better suited for heat-tolerant crops like bush beans. As the season progresses and temperatures moderate, the focus should shift to planting cool-weather vegetables such as kale, spinach, or broccoli transplants. Focusing on varieties with a shorter DTM fully utilizes the narrow window between the summer harvest and the first heavy frost, securing a robust second harvest.