Kawakawa

Kawakawa (Piper excelsum) is remarkably easy to grow and propagate, making it an excellent choice for both beginner and experienced gardeners. As an early coloniser in nature, it establishes quickly and thrives in New Zealand gardens when provided with appropriate conditions. The plant grows rapidly once established and makes an ideal understory species that generates enough shade to naturally suppress most weeds.

From Seed

Growing kawakawa from seed is highly rewarding and allows for genetic diversity in your plantings. Fresh seed provides the highest germination rates and should be collected at the optimal time for best results.

1. Collect ripe orange-red berries from female plants in late summer to early autumn (December-January) when fruit begins turning from green to yellow
2. Extract seeds by gently squeezing berries, then rinse thoroughly to remove all pulp. Alternatively, mash fruit with water and decant off pulp, leaving denser seeds behind
3. Seeds can be sown immediately or dried and stored. For cold stratification, store in moist substrate at 2-5°C for 4-6 weeks in refrigerator
4. Soak seeds in lukewarm water for 24 hours before planting to improve germination rates
5. Sow at 5mm depth in well-draining seed mix, maintaining optimal temperature of 20-25°C
6. Provide bright, indirect light and keep consistently moist but not waterlogged
7. Germination typically occurs within 2-4 weeks under optimal summer conditions, though some seeds may take up to 10 weeks
8. Transplant seedlings when they develop at least two sets of true leaves or reach 10cm height
9. Use heat mats for consistent temperature and maintain high humidity during establishment

Seedlings grow rapidly and can be planted out in permanent positions after one full growing season.

From Semi-Hardwood Cuttings

Semi-hardwood cutting propagation is the most reliable method for kawakawa, maintaining exact parent plant characteristics while providing faster establishment than seed propagation.

1. Take 10-15cm cuttings from healthy, current season's growth during autumn when wood has partially hardened
2. Remove lower leaves, retaining 3-4 pairs at the cutting tip to reduce moisture loss
3. Make clean cuts just below a node using sharp, sterilized pruning shears
4. Dip cut end in rooting hormone powder to accelerate root development (optional but recommended)
5. Plant immediately in free-draining propagation mix composed of equal parts sand and compost
6. Maintain consistently moist conditions in warm, humid environment with temperatures around 20-23°C
7. Provide bright, indirect light and mist cuttings regularly to maintain high humidity levels
8. Root development typically occurs within 4-8 weeks - check by gentle tugging
9. Transplant to individual pots once robust root system has developed
10. Gradually acclimatise rooted cuttings to outdoor conditions before final planting

From Softwood Cuttings

Softwood cuttings taken from new spring growth provide another effective propagation method, particularly suited to spring and early summer conditions.

1. Select healthy, soft new growth from spring flush, typically March-May
2. Take 8-12cm cuttings early morning when plant tissues are fully hydrated
3. Strip lower leaves and treat with rooting hormone if desired
4. Insert into moist propagation medium and maintain high humidity
5. Provide warmth and protection from direct sunlight
6. Expect faster rooting than semi-hardwood cuttings, often within 3-5 weeks

From Layering

Natural layering takes advantage of kawakawa's flexible branching habit and provides an almost foolproof propagation method requiring minimal intervention.

1. Select a healthy, low-growing branch that can easily reach the ground without forcing
2. In spring or early summer, make a shallow wound on the underside of the branch where it will contact soil
3. Bury the wounded section 5-10cm deep in prepared, organic-rich soil, leaving the growing tip exposed
4. Secure the buried section with a stone or wire peg to maintain soil contact
5. Keep the layering site consistently moist throughout the growing season
6. Root development occurs gradually over 6-12 months - check by careful excavation
7. Once well-established roots are visible, sever connection from parent plant
8. Allow newly independent plant to establish for several more weeks before transplanting

Transplanting and Establishment

Successful transplanting requires attention to timing, soil preparation, and post-planting care to ensure rapid establishment and healthy growth.

1. Choose planting sites with dappled light to partial shade, avoiding full sun exposure
2. Prepare soil by loosening and enriching with organic matter such as compost or well-aged manure
3. Space plants 30-45cm apart to allow for mature spread while providing adequate airflow
4. Plant at the same depth as in containers, ensuring root ball is level with surrounding soil
5. Water thoroughly after planting and maintain consistent soil moisture during first growing season
6. Apply organic mulch around plants to retain moisture and suppress weeds
7. Provide temporary shade cloth protection for first few weeks if planting in exposed locations
8. Monitor for establishment signs including new growth and increased vigour

With proper care, kawakawa establishes quickly and begins producing its characteristic heart-shaped leaves within the first growing season, developing into a productive plant for both ornamental and traditional medicinal purposes.