Growing Kale

For fall and winter production (the best kale season), choose cold-hardy varieties: Winterbor (curly, survives single-digit temperatures), Lacinato/Dinosaur (cold-tolerant, excellent flavor), Red Russian (beautiful, tender, very cold-hardy), and Dwarf Blue Curled Scotch (compact, extremely hardy).

For spring production, choose heat-tolerant and slow-bolt varieties: Premier, Siberian, and White Russian are more heat-tolerant than most. Even so, expect spring kale to bolt by late June in most climates as temperatures rise.

For ornamental and dual-purpose, Redbor (deep red-purple) and Scarlet (vivid purple) produce striking color in the garden while being fully edible. These make beautiful border plants.

For fall crops (recommended for best flavor), sow seeds indoors 6–8 weeks before your target transplant date, which is typically 6–8 weeks before the first expected fall frost. Direct sowing in midsummer also works. In zones 8–10, sow in September–October for winter harvest.

For spring crops, start seeds indoors 6–8 weeks before the last frost date, or direct-sow 3–4 weeks before the last frost. Kale seeds germinate quickly (5–10 days) at 55–75°F. Seedlings tolerate light frost.

Direct sowing: plant seeds 1/4 to 1/2 inch deep, 1 inch apart, and thin to 18–24 inches when seedlings have 4 true leaves. The thinnings are delicious microgreens.

Kale is a moderate-to-heavy feeder that thrives in rich, well-drained soil. Work in 2–3 inches of compost and a balanced organic fertilizer (like 5-5-5 or 10-10-10) before planting. Kale prefers a pH of 6.0–7.0 - slightly alkaline soil is fine and actually helps suppress clubroot disease.

Unlike many vegetables, kale tolerates a wide range of soil conditions - from sandy loam to moderate clay. However, it does best with good fertility and consistent moisture. Raised beds or well-amended garden soil produce the healthiest plants.

If you have had clubroot issues with brassicas before, test your soil pH and lime to at least 7.0–7.2. Clubroot thrives in acidic conditions and is suppressed in neutral to slightly alkaline soil. Rotate brassicas on a 3–4 year cycle to prevent clubroot buildup.

Transplant seedlings at 4–6 weeks old, when they have 4–6 true leaves. Set plants 18–24 inches apart - kale needs room to spread. Closer spacing (12–15 inches) works for baby kale production where plants are harvested young.

Plant at the same depth as the nursery pot, or slightly deeper (burying the stem up to the first set of true leaves) to promote a sturdier stem. Water in thoroughly with dilute liquid fertilizer.

Apply 2–3 inches of mulch (straw, shredded leaves, or grass clippings) around transplants to conserve moisture and suppress weeds. In fall plantings, mulch also insulates the root zone as temperatures drop.

Provide 1–1.5 inches of water per week. Consistent moisture is important for tender, mild-flavored leaves - water-stressed kale becomes tough and bitter. Drip irrigation or soaker hoses are ideal for keeping foliage dry, which reduces fungal disease risk.

Side-dress with nitrogen-rich fertilizer (blood meal, fish emulsion, or composted manure) every 4–6 weeks during active growth. Kale is a heavy nitrogen user - it needs the nitrogen to produce its continuous flush of large, nutrient-dense leaves. Signs of nitrogen deficiency include pale green or yellowing lower leaves and slow growth.

For fall/winter crops, reduce fertilization as temperatures drop below 40°F - plants go semi-dormant and excess nitrogen can reduce cold hardiness.

This is what makes kale such a productive crop - you never harvest the whole plant at once. Instead, pick individual outer leaves as they reach usable size (6–8 inches long), leaving the central growing point and at least 5–6 inner leaves intact. The plant continues to produce new leaves from the center, and you can harvest from the same plant for months.

Begin harvesting when plants have at least 10–12 leaves, about 55–65 days after transplanting. Snap or cut leaves at the stem. Harvest in the morning for crispest leaves, or wait until after a frost for sweeter flavor.

Baby kale (leaves harvested at 2–3 inches) is extremely tender and popular for salads. For baby kale production, plant densely (2–3 inches apart) and cut the entire plant at 3 inches tall - many varieties will regrow 2–3 times before needing replanting.

Kale leaves become sweeter and more flavorful after frost exposure. Fall-planted kale that experiences repeated light frosts develops exceptional sweetness - this is the best-tasting kale you will ever eat, and it is a major selling point at farmers markets.

Kale is one of the most cold-hardy vegetables, but you can extend the harvest even further with simple protection. In zones 5–7, a low tunnel (hoops + row cover fabric) over fall kale lets you harvest fresh leaves through December or January. In zones 3–4, an unheated greenhouse or high tunnel enables winter kale production even in brutal climates.

In zones 8–10, kale grows as a winter crop with no protection needed. Plant in September–October and harvest through April, when heat causes bolting.

If kale survives winter (it often does in zones 6+), it will bolt and flower in spring. The flower buds - called kale raab or kale florets - are actually edible and delicious, similar to broccoli rabe. Harvest the tender flower stalks just before buds open. Kale flowers are also excellent for pollinators and beneficial insects.