Since this plant has a reputation for being tricky to grow and propagate by seed, am sharing research as a guide for those who would like...Read More to try. Opinions differ, so hopefully presenting a range of information will help in making informed decisions.
PROPAGATION:
I. From Tom Cothier - Sow moist at 77-87*F for 4-5 weeks; Move to 35*F in darkness for 11-12 weeks. Slowly raise temperature and light levels."
II. From another site:
1) "Sow immediately [in equal parts of river sand, perlite and soilless seed-starting medium (Vermiculite might not work as well for a species needing excellent drainage, because it is said to hold more water for longer than Perlite)]. The viability of [this species] is short or [fresh seed may germinate best.] Stored seed [may require] temperature cycling [for germination]...";
2) "Use repeated cycles of 20*C [~70*F], then 4*C [~40*F] for 3 months each. Germination can be very prolonged.";
3) "This species needs special care as described."
4) "Grow seedling at cool temperature."
CULTIVATION: E. robustus is said to be a cold desert plant (Deno) native to Turkistan, hence its requirements for "...sunny position in a fertile, slightly alkaline (calcareous) soil with perfect drainage. Although [this plant is said to be hardy to zone 6a], the...roots must never become frozen, and in northern regions the dormant plants must have some protection against cold and excessive moisture during winter and early spring, when new growths appear...[Sow] in a warm greenhouse in spring." (Pizzetti and Cocker, Flowers Vol I)
Since this plant has a reputation for being tricky to grow and propagate by seed, am sharing research as a guide for those who would like...Read More