Kale shows up year after year on lists of vegetables with the highest pesticide residues, which is one of the strongest reasons to grow your own instead of buying it at the store. The growing popularity of kale has brought dozens of varieties to home gardeners, from heirloom types passed down for generations to newly developed hybrids. You can choose flat-leaf or curly kale, green, purple, or bicolored types, and even kale that shifts color when cold weather arrives. Sorting through the choices starts before you buy seed, with a look at the ground where the bed will go. A quick check of the slope using the types of levels used in leveling shows whether water will drain away or pool around the roots, and kale dislikes wet feet.
This rundown groups the main kale types, explains how botanists classify them, and pairs each group with practical planting and bed-building advice. The construction details matter as much as the seed packet. A well-drained bed, the right frame material, and a simple season-extension structure separate a productive fall crop from a disease-prone patch.
How Kale Varieties Are Classified
Botanically, kale belongs to two different species, and knowing which one you are growing explains a lot about leaf shape, hardiness, and how the plant behaves in cold weather.
- Brassica oleracea (Acephala group): the true kales. This group splits into Scotch kale with deeply curled and wrinkled leaves and Lacinato kale with dark green, savoyed, blade-shaped leaves.
- Brassica napus (Pabularia group): a hybrid species that resulted from breeding two species together. Siberian and Russian kales belong here, with flat, frilled leaves and the best cold tolerance of any kale.
Once the bed site is chosen, leveling the soil surface matters more than most gardeners expect. A bed that slopes unevenly dries out at the high end and stays soggy at the low end, so rake the surface flat before planting. The same principles behind the types of leveling in surveying apply at garden scale: set a reference point, check the high and low spots, then cut or fill until the surface is even.
Kale Groups at a Glance
| Group | Leaf shape | Cold tolerance | Typical varieties |
|---|---|---|---|
| Scotch (curled) | Deeply curled and wrinkled | Hardy; flavor improves after frost | Blue Curled Scotch, Vates, Winterbor |
| Lacinato (flat) | Dark green, savoyed blades | Hardy to about 20 degrees Fahrenheit | Lacinato, Nero di Toscana, Black Magic |
| Siberian and Russian | Flat, frilled, oak-shaped | Most cold tolerant of all kale | Red Russian, White Russian, Siberian |
| Ornamental | Frilly rosettes, white or pink centers | Frost hardy; color deepens in cold | Peacock, Kamome, Nagoya |
All of these groups grow from the same planting basics: full sun, rich soil, and steady moisture. The differences show up in texture, color, and how long the plants keep producing into winter.
Curly, Flat-Leaf, and Ornamental Choices
Curly kales are the classic supermarket type, with leaves that hold their texture when cooked. Blue Curled Scotch is a dependable heirloom that forms compact plants with finely curled blue-green leaves. Winterbor grows tall and vigorous, with dark green leaves that shrug off snow, while Vates stays smaller and resists bolting longer than most curly types.
Flat-leaf kales bruise less in handling and cook faster than their curly cousins. Lacinato, sold as Dinosaur or Tuscan kale, has savoyed, blade-shaped leaves that keep a silky texture in soups and stews. Red Russian and White Russian belong to the Siberian group, with flat, frilled, oak-shaped leaves and purple or pale stems, and their flavor turns noticeably sweeter after frost.
Ornamental kales grow frilly rosettes in white, pink, and magenta centers that deepen as temperatures fall. They are bred for looks rather than flavor, so treat them as an edible garnish. If you garden on a balcony or patio, ornamental kale thrives in containers beside the seating you furnish with the same attention you give the types of couches for home that anchor an indoor living room.
Top Varieties by Type
- Blue Curled Scotch: heirloom, tightly curled blue-green leaves, very cold hardy
- Vates: compact and slow to bolt, a good choice for spring planting
- Winterbor: tall, vigorous, dark green, among the best for fall and winter harvest
- Lacinato (Dinosaur, Tuscan): savoyed blades, sweet flavor, traditional in soups
- Red Russian: flat frilled leaves with purple veins, sweetest after frost
- White Russian: same growth habit with pale cream stems
- Redbor: deep purple curly leaves that double as an ornamental
- Dazzling Blue: Lacinato type with purple midribs and blue-green blades
Building Raised Beds for Kale
Raised beds suit kale better than flat ground on most sites. They warm up earlier in spring, drain faster after heavy rain, keep the soil loose instead of compacted, and put the harvest at a comfortable height. Kale roots grow roughly 12 to 18 inches deep, so a bed between 12 and 24 inches tall gives the plants everything they need.
Raised Bed Construction Steps
- Pick a spot with at least six hours of direct sun and watch how water behaves there after a rain.
- Keep the bed no wider than four feet so the middle is reachable from either side.
- Strip the sod, dig down a few inches, and set the frame on firm, level ground.
- Cut the frame lumber to length and fasten the corners with exterior-grade screws.
- Staple hardware cloth or landscape fabric across the bottom to block burrowing pests.
- Fill with a mix of about 60 percent topsoil, 30 percent compost, and 10 percent coarse material for aeration.
Bed Height and Reach
A 12-inch bed uses the least fill and suits most kale plantings. A 24-inch bed brings the plants closer to standing height and makes late-fall harvesting easier on the back. Gardeners who want accessible beds go to 30 inches or more, which takes a sturdier frame and a lot more soil.
Brick frames are the most permanent option and can double as a garden feature. The same types of bricks used in house walls work here, from common clay units for the visible face to harder engineering bricks where the wall sits against wet soil.
Choosing Durable Materials for Garden Beds
The frame material decides how long the bed lasts and how much maintenance it needs. Untreated pine is cheapest but rots within a few seasons at ground contact. Cedar and redwood resist decay naturally for a decade or more. Galvanized steel lasts 15 to 25 years but heats up in full sun. Concrete block is inexpensive, heavy, and nearly permanent.
| Material | Expected lifespan | Relative cost | Notes |
|---|---|---|---|
| Cedar or redwood | 8 to 15 years | Medium | Naturally rot resistant, weathers to gray |
| Untreated pine | 3 to 5 years | Low | Rots at the soil line; line with fabric |
| Brick or masonry | 30 years or more | High | Needs mortar or careful dry stacking |
| Concrete block | 20 years or more | Low | Fill the cores with soil for stability |
| Galvanized steel | 15 to 25 years | Medium | Sharp edges; warms the soil in spring |
Material choice is a structural decision. The types of failures experienced by different construction materials in structural engineering show up in miniature in garden beds: pine frames rot from ground contact, uncoated steel corrodes where it meets damp soil, and masonry cracks when frost heaves the base. Match the material to the moisture exposure and the bed will outlast the kale.
Lining and Drainage
Whatever frame you choose, keep the soil in and the pests out. Line the inside walls with landscape fabric so soil does not wash through the gaps, and lay a coarse drainage layer of gravel or crushed stone at the bottom in heavy clay areas. Drill or leave weep holes in solid frames so excess water can escape instead of saturating the root zone.
Cold Frames, Hoop Tunnels, and Season Extension
Kale is a cool-season crop that tastes best after frost, when the plant converts starches into sugars. Most varieties survive down to about 20 degrees Fahrenheit, and Siberian types shrug off much colder weather. Season-extension structures let you keep harvesting through winter in most climates.
Building a Simple Hoop Tunnel
- Cut PVC conduit or metal electrical conduit into hoops about 6 to 8 feet long, depending on bed width.
- Drive a short stake at each end of the bed and slip the hoop ends over the stakes.
- Space the hoops 4 to 6 feet apart, then run a ridge line along the top to keep them aligned.
- Drape row cover or greenhouse film over the frame and anchor the edges with sandbags or soil.
A hoop tunnel is a series of small arches, and the way the cover sheds wind and snow follows the same structural logic as the different types of bridges listed in bridge construction, from beam spans to arched forms that carry loads without intermediate supports.
A cold frame works the same way on a smaller scale. Build the back wall 18 to 24 inches tall, slope the glazing toward the south, and prop the lid open on warm days so the plants do not cook. Polycarbonate panels weigh less than glass and hold up better in hail.
Planning the Layout and Finishing Touches
Space kale plants 12 to 18 inches apart with rows 18 to 24 inches apart, and sow a new batch every two to three weeks for a steady harvest. Kale grows well beside beets, celery, onions, and garlic, while strawberries and other heavy feeders tend to compete for the same nutrients.
A productive backyard combines several building types: a cold frame for early spring seedlings, a tool shed for supplies, and a small greenhouse if you want salads year-round. Each structure has its own footprint, so sketch the layout on paper before you pour or dig anything.
Final Planting Checklist
- Test the soil and aim for a pH between 6.0 and 7.5
- Sow seeds half an inch deep and thin seedlings to the final spacing
- Water consistently and mulch to keep the roots cool in summer heat
- Start harvesting baby leaves about 30 days after sowing
- Cut the outer leaves first so the crown keeps producing for 60 to 75 days or more
If you build a masonry bed, choose the binder with the same care as the brick. Lay the wall with one of the special types of mortar and their applications suited to garden exposure, such as Type N for above-grade walls and Type S where the wall meets soil.