Tropaeolum success

Bill Dijk
Thu, 19 May 2005 03:12:44 PDT
Mary Sue wrote:

> I have germinated seed of Tropaeolum on occasion, but even then lost it
> later. I had no luck with some T. azureum seed that a kind friend from the
> UK gave me last fall. I was so disappointed. Anyone with successful
> methods for growing this from seed please speak up.
> So it was with low expectations that I sowed T. brachyceras that I was
> I'm now wondering if I need to grow the ones I have in my greenhouse if I
> want to get them to bloom. Maybe I'd have better luck. Has anyone in our
> group figured out a successful way to grow Tropaeolums from seed? Does the
> time you start them matter? Clifton suggested day length may have some
> effect on T. azureum. Does the seed need to be soaked first? Obviously a
> bigger pot would be helpful.


Dear all,

As I mentioned before, I have been reasonably successful in germinating and
growing these charming, delicate, often temperamental and unpredictable
Tropaeolum species, especially the exquisite Trop.azureum.
I don't think that I am doing anything special as far as the cultivation of
the Trops is concerned, apart from a sensible horticultural application.
Perhaps our climate may be more congenial to growing these sometimes
difficult species.
When it comes to sowing the seed, I usually sow the seed late winter, early
spring, (normal seed-tray 10 cm deep) in a free draining seed compost, with
perhaps extra pumice added and covered with 5-10 mm. of coarse horticultural
sand, to keep the weeds down.
I keep the seed boxes outside (coolish 5-10 C.) on open, covered benches,
away from the frost and heavy rain, to reduce the damage to the delicate
threadlike seedlings once they're up.
Seed should germinates quickly, under normal frost-free conditions .
As the plants grow, water freely and grow on in a cool greenhouse or
conservatory with plenty of ventilation.
Its important to make sure the young seedlings don't get waterlogged, or to
hot, or both, which could result in rotting or damping off.
Keep them growing as long as possible, until they go dormant naturally, then
store or keep little tubers dryish (not bone dry) until new growth appear.
Generally they are best left undisturbed once established.
When it comes to planting the mature (freshly sprouted) tubers again,
sometimes during autumn , I usually select a suitable deep container
(as shown with Tropaeolum on the wiki)
I plant them as normal in a well drained slightly acid potting mix, 10 cm.
deep in a sunny position.
I usually attach the wire netting around the container for support at
planting time to avoid damage to the delicate new shoots later on, which
threads seem almost invisible.
I place/plant the tubers towards the outside rim of the container for
immediate support to the wire netting which is vital for a good start.
They require sufficient moisture during the growing season, but don't
overwater, which could result in rotting of the tubers.
Aftercare when dormant: As the foliage dies, the pots or containers should
be stored in a dry, but cool place, gradually withhold water, until compost
nearly dry.
The tubers can then be carefully shaken out and repotted or split up if
Restart into growth next spring by gradually increasing the watering.
Tuberous species should be left undisturbed as long as possible.

Best wishes,

Bill Dijk

PS: When I have seed to spare at the end of the season I might donate to the
PBS BX if USDA will let me.

Tauranga, New Zealand :annual rainfall :1250 mm.
Sunshine hours, mean annual  :  2350 hours.
Temp.mean max.Summer : 25°C.   winter:///15°C/.
Temp.mean min. Summer :14.5°C. Winter: 5°C.
Wet mild Winters with occasional light frost.

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