How to Grow Kale in a Greenhouse

How to Grow Kale in a Greenhouse? Growing Tips and Tricks

Choose suitable varieties, sow seeds directly or in trays, and maintain optimal conditions—full sun, 60-75°F, well-draining soil. Space plants 12-18 inches apart. Enjoy nutrient-rich kale in diverse dishes, enhancing meals with health benefits.


Plant kale in rows spaced one foot apart. Water seeds well after planting to keep soil moist. Expect germination in 5-7 days. Once seedlings develop two true leaves, thin them to 12 inches apart for best growth.

Kale, a resilient cold-season crop, thrives year-round in greenhouses. Rich in vital nutrients, it is an easy-to-grow vegetable, unlike its fussier relative, cabbage.

For successful growth, kale needs full sun, moderate temperatures, regular watering, and nutrient-rich, well-draining soil. While additional heat might not be necessary, grow lights can supplement light requirements.

With various kale varieties available, you can enjoy a continuous harvest by meeting these straightforward growing conditions.

Growing kale in a greenhouse

Growing kale in a greenhouse

To start growing kale in your greenhouse, choose the right variety suited to your climate and preferences.

Begin by planting seeds to have better control over growing conditions and save money compared to buying seedlings. While purchasing seedlings is an option, starting from seeds offers more flexibility and cost-effectiveness.

Choosing the best kale cultivar to plant

When choosing kale varieties for your greenhouse, consider the following popular options:

  • Red Russian Kale: Fast-growing with flat oak-shaped leaves, offering a tender texture and mild sweetness.
  • Siberian Kale: Thrives in cooler environments, developing sweeter taste after mild frost. Features large, flat leaves with ruffled edges.
  • Tuscan Kale (Dinosaur Kale or Black Cabbage): Heat and cold tolerant, producing large, dark green leaves with a bumpy texture, offering both culinary and ornamental value.
  • Curly Kale: Versatile and common in supermarkets, featuring a nutty sweetness and easy-to-grow curly leaves.

How to sow seeds of kale

How to sow seeds of kale

For growing kale in a greenhouse, consider either direct-sowing seeds or starting them in plug trays. Having backup seedlings is advisable for even germination. Planting can be done in late winter, early spring, or early fall, but avoid summer due to the risk of bolting caused by excessive heat.

How to sow kale seeds directly

For direct-sowing kale seeds, plant them in the ground or raised beds, about twice as deep as the seed size (no more than ½ inch) and 6 inches apart. If planting in rows, keep them at least one foot apart.

Kale seeds typically germinate in 5-7 days. Water thoroughly after planting and ensure the soil remains moist in the initial days.

Once seedlings have at least two true leaves, thin them to 12 inches apart for optimal growth.

Growing kale in trays: a guide

For plug trays, place one kale seed in each cell and ensure the soil stays moist for uniform sprouting. Once seedlings have 2-3 true leaves, transfer them into the ground or pots for continued growth.

Kale maintenance in a greenhouse

Kale maintenance in a greenhouse

Once kale is established, it is relatively low-maintenance. However, understanding its specific needs is crucial for optimal growth. Let’s explore some of these requirements in this section.

Minimal required

Kale thrives in full sun, requiring a minimum of 6 hours of direct sunlight daily for healthy growth. If your greenhouse is freestanding without obstruction from trees or nearby structures, providing ample sunlight, you’ll have no trouble cultivating this crop.

Kale can tolerate partial shade, receiving 4 to 6 hours of direct sunlight per day. However, its growth will be slower compared to full sun conditions.


For optimal growth, kale prefers temperatures between 60°F and 75°F. Plant seeds when soil temperature exceeds 45°F for better germination.

Kale withstands frost well, enduring temperatures as low as 20°F. Light frost can even enhance its sweetness.

However, kale is sensitive to heat, struggling above 75°F and prone to bolting above 80°F for consecutive days. Avoid planting in late spring to late summer or maintain cooler greenhouse conditions to prevent bolting.

Conditions of Soil

For optimal growth, plant kale in well-draining, nutrient-rich soil. Kale is not picky about pH, preferring it between 6.0 to 7.5.If planting directly, dig soil to a foot depth, break clumps, and incorporate compost or manure. For raised beds or containers, use a mix of potting soil and compost, adding straw or coconut husks for drainage. Boost nutrients with worm castings or organic fertilizer for healthier kale plants.

Plant separation

Space kale plants 12-18 inches apart for optimal growth. When transplanting from nursery or plug tray, maintain this spacing to provide ample room for development.


Well, growing kale in a greenhouse offers a rewarding experience, providing a steady supply of this nutrient-rich vegetable year-round. By following simple steps such as choosing the right variety, sowing seeds appropriately, and maintaining ideal growing conditions regarding sunlight, temperature, soil, and spacing, you can ensure a successful harvest.

Whether you are a seasoned gardener or just starting out, the resilience of kale makes it an excellent choice for greenhouse cultivation, offering both culinary versatility and nutritional benefits. With a little care and attention, your greenhouse can yield bountiful harvests of fresh, flavorful kale to enjoy in various dishes, adding a healthy touch to your meals throughout the seasons.