We are planning an experiment trialling Porophyllum spp. in several
gardens across Norway next summer and the other Coriander-surrogates
will probably also be compared. I am therefore very interested if
anyone can help us get hold of seed (or plants in the case of
Houttuynia) of a) Coriander "Santo" or other slow-bolt varieties; b)
Porophyllum species and cultivars apart from P. ruderale; c) the
Houttuynia cultivar with Cilantro scented leaves. We want as good a
range of these plants as possible. We'll make it worth your while.

Living in Norway, not far south of the Arctic Circle, with very long
summer days, Cilantro (Coriandrum sativum) which is adapted to
Mediterranean climate and day length, tends to bolt. I have also tried
Santo, but this slow-bolt variety doesn't seem that much better under
our conditions.

I have also tried other Coriander "taste-alikes" mentioned here. My
experience is that Vietnamese Coriander (Polygonum odoratum) quickly
becomes too strong flavoured in the summer. It isn't hardy in our
climate (minimum –24C) and we therefore overwinter indoors. Mexican
Coriander or Culantro (Eryngium foetidum) needs warm summers and must
be kept in the shade. I grow it indoors. If it is kept on the window
sill it quickly bolts, but if kept out of the light it produces plenty
of leaf which has a pleasant Coriander-taste (probably a bit milder
than Cilantro).
My personal favourite is Porophyllum ruderale, another Mexican herb
(known as Quilquiña) with a taste which strongly resembles Coriander.
This is an annual in the Compositae (the Daisy Family). In my rather
mild climate this plant produces plenty of leaf outside (we sow the
seed inside in the spring and transplant out in May/ early June) once
the soil has warmed up. I like the taste of this plant. It's a bit
stronger than Cilantro, so use sparingly. There are also various
cultivars and P. colorata is another species which is used. There may
well be others too. These plants are often collected in the wild in
Mexico. If your season is too short for seed to set, you can do as we
do and keep one plant in a pot, which is taken indoors when the cold
weather arrives. We harvest seed indoors in December.

Finally, there is Houttuynia cordata (Himalayan Water Creeper). This
is in yet another plant family – the Saururaceae. There are several
cultivars including "Chameleon" with beautiful multi-coloured
variegated leaves. Although this species has highly aromatic leaves,
the ones I have do not smell strongly of Coriander. There is supposed
to be a Japanese cultivar with leaves which are much closer to
Coriander, but I've never seen this advertised.

Steve.