Janet

When raising from seed, Metrosideros umbellata is more or less the same
as the other species in basic growing requirements. A mildly acidic
compost that's not too high in phosphates suits it well, so A.B.
Ericaceous more or less fits the bill. When the seedlings are large
enough to handle, prick them out into small pots adding a small amount
of extra grit/sand/perlite to guarantee good porosity. Keep the
seedlings in good light and pot-on as necessary. As they develop
stronger roots, you can improve the compost mixture by mixing the AB
with equal parts, good quality JI No2.

Young Metrosideros should not be allowed to become too dry if they are
to maintain a good growth rate so keep them moist at all times. Try to
maintain winter temperatures above 5C. for the first few years. When
planting out (at about 3 - 4 years - 1m. high), plant them in the
sunniest, most wind-sheltered spot you can provide and protect them
during frosty weather. First flowering can be as early as 3 years, but
generally plants won't be really getting into their stride until they
are 5 or 6 years old. Well worth the effort, its a very fine species.