concerning gladiolus alatus, according to a south african book sprouting the seed is very easy. and takes 2-4weeks to sprout. it must be planted in march in s/africa...so n/hemisphere september . plant in pots/seed trays at least 8inches deep with equal quantities of peat, compost and sand. the pots must be thoroughly soaked and the seed sown in a 5mm deep furrow and covered. keep moist and shaded . the seedlings will appaer as fin green hairs and must be kept moist and shaded till the end of the growing season(winter). weak plants should be kept in pots for 2 growing seasons(2winters). keep pot dry during summer and allow to die back. You are now ready to replant in garden or replant in pots at the appropriate distance from another when the next autumn commences.
for aristea sow seed in september in manure, compost rich, peat rich soil and keep rather damp(aristea is a water loving plant) germination takes place in a month's time. keep ssedlings in semi shade and do not allow to dry out AT ALL! plant out in the spring when they are 3inches high. they will grow to a foot in the 1st year and flower in the 3rd year.remember they'll only like full sun in the morning and prefer a semi-shaded positio close to(but not in) water
hope that helps!