Polyvert
Chives in the US

Chives are pretty straightforward from seed, to be honest. You won't often find them as plug plants, so seeds it is. For most folks in zones 5-7, you're looking at sowing from March through May, but warmer zones can start earlier, and colder ones a bit later, like April or May in zones 3-4. Just check your USDA zone for the best timing. Sow seeds about 1/4 inch (6mm) deep, either direct in the ground or in pots indoors for a head start. Pop a few seeds together, maybe 10-15, in a little clump, then space these clumps about 6-8 inches (15-20cm) apart. They don't mind a bit of cold, but a steady temperature around 60-70°F (15-21°C) gets them going.

If you started your chives indoors on the windowsill, once they're a few inches tall and the risk of the last frost has well and truly passed, you can get them outside. Just harden them off slowly for a week or so, bringing them in at night if it's chilly. Plant those little clumps about 6-8 inches (15-20cm) apart in a sunny spot with good drainage. They're not fussy, and they do proper well in containers too, so even if you've only got a small patio, you can still get a good crop. No need for any fancy support, they stand up on their own.