Plant Doctor Archive

Propagating natives from seed

I AM a retired sheep and cattle farmer who now wants to propagate natives so I can fill in any empty space I can find. I have helped vegetate the cliffs of Kairahau Beach to the tune of some 300 potted lancewoods, kowhai, cabbage trees and coprosmas for birds. Have you any hints for propagation of titoki and puriri from seed?

GROWING titoki (Alectryon excelsus) from seed is quite straightforward. You need to collect the seed when it's fully ripe, which is normally mid to late summer, depending on the season. When the seed is ripe, the capsules on the trees start to split, exposing the shiny black seed with its bright red fleshy aril attached. When the first few seeds are visible you can collect all the capsules and open them by hand to remove the seeds. Clean off as much of the red flesh as practicable (it's usually quite easy to pick off by hand) and sow the seeds straight away in a free-draining seed-raising mix. They'll probably take a couple of months to germinate, depending on your conditions. If cold, they may not do much until spring.

With puriri (Vitex lucens) you can sometimes find some ripe (red) berries hanging on trees at any time of year, but usually there's a good crop late summer to early winter. The best way to clean them is soak in water for a few days until the flesh goes mushy. Then mash them up and remove the quite large, blackish seeds.

There are a couple of schools of thought as to what you should do next. Some people say stratifying the seeds encourages more even germination, as puriri seeds can be erratic. Others recommend you sow them straight away and leave in a cool place over winter. Then simply remove seedlings for potting up as they appear the following season, leaving the remaining seeds to germinate when they will.

Stratifying involves mixing the seeds in moist sand and placing the mixture in a sealed container or plastic bag in the fridge for six to eight weeks before sowing. You need to make sure the seeds remain moist while in the fridge. After stratifying, sow them and place in a sheltered spot. Avoid extremely high temperatures - don't put them in a poorly ventilated greenhouse and don't let them dry out.

You may be interested to know you can also propagate puriri from leafy cuttings taken any time from mid to late summer. Ideally though, for revegetation purposes, you should raise them from seed to allow for as much genetic variation as possible, and where practicable collect the seeds from a range of different trees close to the area you intend to plant.

Reproduced with permission from the former Weekend Gardener magazine. The views expressed here are not necessarily those of the RNZIH.