The Ultimate Guide to Tree Collards

1. What Are Tree Collards?

Tree collards (Brassica oleracea var. acephala) are perennial members of the brassica family. Unlike traditional annual collards, kale, cabbage, and broccoli, tree collards grow as perennial shrubs or small trees that continue to produce year-round without needing to be replanted each season.

• Hardiness: Hardy to around 20°F (-7°C).

• Lifespan: In mild climates, plants can live for up to 20 years.

• Growth: Can reach over 8 feet tall if staked and grown in fertile soil.

2. Choosing Your Planting Method

A. Rooted Plants

• Best for: Beginner gardeners or those needing fast results.

• Benefits: Easiest and fastest route to harvest; less fussy and adjust quickly to garden beds.

• Planting Window: Best planted in spring or autumn (avoid planting in extreme heat >90°F / 32°C or cold <40°F / 4°C).

B. Cuttings

• Best for: Intermediate to experienced growers (requires daily attention for 4–8 weeks).

• Best Season: Root in spring or autumn when temperatures are between 50°F and 70°F (10°C–21°C).

How to Propagate Tree Collards from Cuttings:

1. Take Cuttings: Take 4–6 inch cuttings from fresh growth tips. Make the bottom cut at an angle. Ensure the stem thickness is at least pencil-wide.

2. Strip Foliage: Strip off all leaves except for 2–3 tiny leaves at the very top (reduces moisture loss).

3. Potted Medium: Fill a 4-inch or 1-gallon nursery pot (with ample drainage holes) with high-quality organic potting soil (or a mix of perlite, vermiculite, sand, and compost).

4. Planting: Insert the cutting stem two-thirds of its length into the soil and firm down gently.

5. Light & Water: Keep soil consistently moist but never waterlogged (usually requires daily watering). Provide semi-shady or dappled light in warm weather; full sun in cooler weather.

6. Establishment: Wait 4–6 weeks until new leaves sprout and roots show through drainage holes before transplanting into the garden.

C. Seeds

• Notes: Some varieties produce flowers and viable seeds. Flowering does not mean the plant is dying.

• Caution: Brassicas cross-pollinate easily, so seed-grown plants may vary slightly from the parent plant.

3. Location, Soil & Climate Requirements

• Sunlight Requirements:

• Mild/Temperate Climates: Full sun.

• Hot Climates: Afternoon or dappled shade (e.g., under a deciduous canopy).

• Soil Conditions: Prefers well-draining soil rich in organic matter with a pH around 6.5, though tolerant of varied soils.

• Spacing: Space plants 2.5 to 3 feet apart on center.

• Container Growing: Can be grown in large containers (minimum 15-gallon / half wine barrel size).

• Overwintering Cold Protection:

• Protect plants if temperatures drop below 25°F (-4°C).

• Keep a back-up plant in a pot that can be brought indoors during severe frosts.

• Fridge Storage Trick: Take cuttings before winter, wrap them in a plastic bag, and store them in the refrigerator for up to 2 months until ready to root in spring.

4. Care & Maintenance

Watering

• Requires low to moderate water once established.

• Highly drought-tolerant (develops a protective white powdery bloom on stems during dry periods), but supplemental water is needed for larger yields and larger leaves.

• Avoid waterlogging: Tree collards cannot tolerate sitting in soggy, flooded soil.

Fertilizing

• Nitrogen: If growth stalls or leaves are pale, apply organic nitrogen sources like fish emulsion. Avoid high-chemical synthetic fertilizers as they induce rapid, weak growth that attracts pests.

• Calcium: Apply ground oyster shell flour or ground eggshells quarterly.

• Micronutrients & Mulch: Apply rock dust bi-annually and top-dress annually with fresh compost and mulch.

Pruning & Staking

• Staking: To grow as an upright tree up to 8+ feet tall, tie the main stem to a heavy metal T-post or rebar (at least 6ft above ground). Unstaked plants will sprawl across the ground and form a low 2–3ft bush.

• Pruning: Prune tip growth regularly (quarterly or during harvest) to prevent plants from getting leggy, woody, or prone to wind damage.

5. Pest & Disease Management

• Aphids: Usually far less problematic on tree collards than regular kale/broccoli. Natural predators (like ladybugs) usually keep populations under control.

• Cabbage White Butterflies / Caterpillars: Hand-pick green caterpillars from the undersides of leaves.

• Powdery Mildew: Common on older lower leaves during hot summers; simply strip off affected leaves and compost or feed to livestock/poultry.

• Deer & Livestock: Ruminants love tree collards, so protect beds with deer fencing.