PlantFiles: Blue Nasturtium
Tropaeolum azureum

Relatively easy to germinate. This seed germinates at about 40 degrees temperature. And begins making a taproot/tuber fast.

Tropaeolum azureum (Chilean endemic species) is a lovely climber with bright blue to deep purple flowers with a white center, produces a tuber (4cm diameter – 1.5”) and blooms from early to late spring. T. azureum reaches a height of approx. 1.5m (59”)

Requires well-drained slightly humid soil, neutral pH, high luminosity and full sun. Also requires support to climb. Normally they will bloom the second year if grown from seeds (mine bloomed the first year!), although from the third year on they will have the most amazing flower-show.

Chilean native Tropaeolums require very deep pots if you do not want to plant them in the soil. They also like to have their tubers/roots in the shade (covered by other plants) and require a shrub or a trellis to climb on.

Sowing recommendations: propagate from seeds in autumn in a mix of: 1 portion compost, ½ portion regular garden soil and 1/3 sand. Cover the seeds with a fine layer of sharp river sand. They will germinate mid to late winter and should not be transplanted before the first year, after they have lost their foliage and have formed a tuber.

Since the tubers bury themselves very deep into the soil in nature, if you want to grow them you must use sowing pots with a depth of at least 7" (18cm). Sow no more than 3 seeds per pot and do not transplant them before the tubers have developed to a proper size after one year. Soil must be kept humid, not wet.

These Tropaeolums require some cold to germinate. Therefore, if your climate is warmer than a zone 9b, they will require some cold treatment. Proceed as described before, then cover with a plastic bag and seal it. Place it in the less cold part of the refrigerator (usually the vegetables compartment) for two weeks. Check them permanently and if they germinate before this period is over, take them outdoors. If the have not germinated after 2 weeks, take them outdoors for 2 weeks (without the plastic cover) and then repeat the refrigerator procedure.

As with so many other Chilean Native plants, good drainage is essential. If the tubers are planted in soggy soil they will rot.

Once the blooming period is over, foliage will die back. At this time start watering them only a bit once every fortnight if it does not rain in your area.