PLANT-RAISING FOR REVEGETATION
MANUKA & KANUKA (best sown March to August)
Suitable containers: Plastic root-trainers (small size) held together in wire trays are the most economical, compact and convenient. Small planter bags (PB three-quarter) are a manageable alternative; they can be held together and carried in milk crates.
Fresh potting mix: Any commercial brand, available in 40-50 litre bags, will do. Topping- off with finer seed-raising mix can be helpful.
Fresh eco-sourced seed: The Friends of Mangemangeroa committee have permission to collect seed from the reserve.
Water: A constant supply.
Free drainage: Containers should be in trays or crates that hold them clear of the ground.
Fertilizer: Liquid or slow-release.
An open, sunny site: Manuka dislikes shade.
Root protection – minimum disturbance and exposure when plants are being handled.
Time from sowing to planting: 9-12 months.
- Fill containers with damp potting mix. Firm down, top up and water.
- Sprinkle a light pinch of seeds onto the mix in each container and water it in using a fine-rosed watering-can. Do not bury this fine seed.
- Set out containers in an open site with protection from slugs and snails.
- Look for germination in 2-3 weeks.
- Delay thinning, leaving one plant per container, until plants reach about 5cm, when strongest growers can be identified and retained. Thinnings may be transplanted, but expect some losses.
- Encourage growth after thinning by applying Osmocote granules.
- Plants should be ready by the following May/June for planting out. 50cm is an ideal height; it can be helpful to trim them back to that before planting.
TREES FROM FOREST DUFF (Collect May to July; lay out July or August)
- Store bag of moist duff in cool shade.
- Prepare seed-trays by half-filling with damp potting mix. Top up with forest duff, firm down and water well.
- Cover trays with shade-cloth, which also keeps birds and alien seeds out, and keep moist. Protect against slugs and snails.
- Most germination will take place from September to November. Delay weeding until plants are big enough to identify.
- Use supports to raise shade-cloth clear of emerging seedlings.
- In December, prick out seedlings into separate pots, planter-bags, or root-trainers, and place in semi-shade.
- Apply liquid fertilizer or Osmocote, provide more light and keep well watered through summer and autumn.
- Harden off in full sun from March onwards.
- Larger specimens will be ready to plant out May/June. Avoid disturbance to roots and their ball of soil.
- Hold until next season plants that have not reached 30cm. Over winter they may need shelter from frost.
LARGER FRUIT and SEEDS (e.g. karamu, mahoe, pigeonwood, taraire, karaka, puriri, kahikatea, kauri)
When collected these can be buried just under the surface in a tray of potting mix or germinated with forest duff. Kowhai seed needs to have the hard casing chipped off one end. OR The larger seeds ie tarairi, karaka, kohekohe, can be buried directly into the longer root trainers (which way up doesn’t matter). One seed per compartment.
Pioneer species are species which will grow on exposed sites (sites which do not have tree cover) ie manuka, kanuka, karamu, cabbage tree. Manuka and kanuka need full sun but karamu will tolerate both shade and full sun. These species take about 9 months from sowing of seed until ready for planting out onto the chosen site. They are ideal plants for school students grow and plant out.
Cabbage trees with their deep root systems are excellent species for planting in the more wet areas.
The next group (successional plants) take longer; 12 months or more to grow to a stage where they can be planted out under the shelter of the karamu and manuka. These species include mahoe. mapou. kowhai, totara, pigeonwood, puriri. They will happily tolerate full sun, but need protection from wind.
Kanuka forms a dense a canopy that does not let enough light through for the successional plants. Thus where kanuka is closely planted no understorey planting is needed and the site is best left alone to let nature do its work. After about 20 years the canopy will open and seed deposited by birds and wind will germinate and grow.
Ground conditions too, affect the success of planting. Manuka tolerates wet “feet”; kanuka does not.
To tell the difference between manuka and kanuka look for tiny hairs on new shoots. Manuka has tiny hairs; kanuka does not. These give manuka a silvery appearance. Manuka also feels prickly on the older foliage.
Collecting and sowing of seed.
Kanuka, manuka, karamu, pohutukawa seed won’t keep; collect it and sow it by placing on top of the soil (don’t bury it) and water it in using a watering-can with a fine rose.
Tairaire, tawa and kohekohe: bury shallowly in humus.
Cabbage tree, kahikatea, totara and nikau are easy to germinate; mix in the surface layer and keep moist.
Titoki: scrape off the black bit of the seed and bury. For puriri scrape the “lid” from the outside of the four “domes”. In nature this scraping is achieved by the grinding in the crop (gizzard) of the birds.
To successfully germinate kowhai nick it at one end. Birds do not eat kowhai seeds.
All germinating seeds need protection from hungry slugs (bait) and foraging birds and cats (plastic netting). Once they have leaves they need more light. Manuka and kanuka need sun.