Chicory is a versatile plant cultivated for several purposes, including its leaves used as salad greens, its roots as a vegetable, and its roasted roots as a coffee substitute. The precise timing of planting chicory seeds is highly dependent on the part of the plant intended for harvest. Growers must align their sowing schedule with the seasonal temperatures required to optimize either leaf production or root development.
Optimal Timing for Leaf Production
Cultivating chicory for its leaves, including varieties like radicchio and sugarloaf, requires cool weather to produce tender, less bitter foliage. Planting can occur in early spring as soon as the soil becomes workable, approximately four to six weeks before the last expected frost. This spring planting allows the chicory to establish itself and produce a harvestable leaf rosette before the intense heat of summer arrives. Leaf chicory struggles when temperatures exceed 75°F.
High heat causes the plant to “bolt,” or prematurely send up a flower stalk, which redirects energy away from leaf production and results in excessively bitter greens. For a continuous supply, succession planting should be utilized, with small batches of seeds sown every few weeks throughout the spring. A second, often more successful, planting window opens in late summer or early fall, roughly 8 to 10 weeks before the first expected hard frost.
This late-season timing ensures the plants mature during the descending temperatures of autumn. Cooler weather naturally enhances the red coloration in radicchio types and improves the overall flavor and texture.
Optimal Timing for Root Development
When the goal is harvesting the root, a longer growing season is necessary. Root chicory requires 120 to 150 days from seeding to harvest to develop a thick, fleshy taproot. Planting is generally scheduled for mid-summer, commonly in June or early July, to allow the roots enough time to mature before winter.
This mid-summer timing ensures that the roots develop fully throughout the late summer and fall, accumulating starches. The roots are traditionally harvested after the first hard frost. This frost is believed to initiate a process converting stored starches into sugars. This natural conversion improves the flavor profile of the root, making it more desirable for roasting or forcing blanched heads, known as chicons.
Preparing the Site and Soil
The site must be prepared to accommodate the plant’s specific needs, especially for taproot development. Chicory performs best in a location that receives full sun, though it can tolerate partial shade. Soil structure is particularly important because chicory develops a deep taproot that can be impaired by compaction.
The planting site should feature deep, loose, and well-draining soil to encourage straight root growth and prevent the taproot from splitting or forking. Incorporating well-decomposed organic matter or compost before planting can enrich the soil and improve its texture. Chicory prefers a soil pH that is slightly acidic to neutral, optimally falling between 5.5 and 7.0.
Sowing and Thinning Practices
Sowing chicory seeds requires attention to detail to ensure successful germination and growth. Seeds should be planted very shallowly, covered with only about 1/4 inch of soil, as deep planting can impede emergence. After sowing, the soil should be kept consistently moist to support germination. Germination typically occurs within 7 to 21 days.
Once the seedlings have developed three to four true leaves, thinning must occur to ensure adequate space for development. For leaf varieties destined for fresh greens or small heads, seedlings should stand about 6 to 8 inches apart. Root varieties require a greater distance to accommodate the thick taproot, meaning these seedlings should be thinned to a spacing of 8 to 12 inches between plants. Proper thinning prevents overcrowding and allows the plant to allocate sufficient resources to either the leaf rosette or the developing root.