Red Giant
Mustard Greens in the US

Right, so mustard greens are a cool season crop, like I say, so you want to get them in when it's not too hot. For zones 3 and 4, April to May and then July to August is your window. Zone 5 can start a bit earlier in March, through April and May, then again in August and September. Zones 6 and 7, you're looking at February or March, April, then August through October. And for zones 9 and 10, January and February, March, then September right through to December. You can sow them direct outside, about half an inch deep, or start them indoors if you want to get a head start, then plant them out. Give them a few inches between seeds, then thin them out later. A little succession sowing every couple of weeks means you'll have a continuous supply, you know what I mean?

Once your seedlings are up and doing well, you’ll want to thin them out a bit, maybe to about 6 to 8 inches apart, so they've got room to really grow. If you started them indoors, harden them off for a week or so before they go outside, just to get 'em used to the weather. They'll do grand in containers too, if you're short on space, just make sure they've got enough room for their roots.