10 seeds To sow gladiolus from seed, place them in moist soil outdoors for direct sowing or use cool, damp conditions to stratify the seeds (chill them) indoors. Then sow the seeds, which often need a period of cold to germinate evenly, in a potting soil or coco coir mix, keeping the soil moist and placing them in bright light after germination, and plant out after hardening off.
