Hello, I’m trying to germinate Pohutukawa (metrosideros Excelsa). I’ve tried for two years in a mini greenhouse in my hous and have had zero success. This year I’ve purchased heating pads to go underneath the seedling trays. I woud very much appreciate any other tips or tricks for germinating Pohutukawa or similar plants.
Thank you for contacting Toronto Master Gardeners
I am assuming you have seeds for germinating Pohutukawa (Metrosideros excelsa) or the New Zealand Metrosideros excelsa. The seed must be sown fresh; even if left for a few weeks before sowing viability can drop, especially if seed is allowed to dry out. Very difficult from cuttings, though soft wood water shoots give the best results. Can be grafted onto seedlings.
Sowing suggestions: Spread the small seeds over sowing mix and can be covered with a light covering or medium like sand. Do not cover them with soil because it is a light germinating species. Sow in bright light with temperatures of 70-75F (20-25 C). Keep the soil continuously moistened by covering the growing container with glass or plastic to hold the moisture in. Yes, adding a source of heat would assist in the germination of the seeds by keeping a constant temperature of 20 to 25 C.
This paper from Massey University of New Zealand provides detailed information on the light requirements for germination of Metrosideros excelsa plants.
And a Youtube video of germinating Pohutukawa being covered with a light medium.