From seed, mustard germinates quickly and you can start harvesting leaves in about a month. Depending on the variety, you can get purple leaves... curly leaves... or even huge leaves. I cut off leaves as I want them and the plant continually produces new ones. I can barely keep up with the 24 or so plants I have going right now.
Another benefit of mustard: it can kill nematodes when used as a green manure. I plant on hacking some of my mustard viciously into the soil as soon as it starts bolting in the spring, then planting something else in the bed. DIE NEMATODES! DIE!
Of course, if you let the plant go to seed, you can make your own delicious mustard from the resulting seeds. I might save some to try that as well... because in the econopocalypse, we might really start missing condiments. Especially as we're forced to eat rats and gnaw on old boots for sustenance.
If you haven't done it before, set aside some space for mustard this year... it's well-worth growing.
Latin Name: Brassica juncea
Type: Cool-season annual
Nitrogen Fixer: No
Exposure: Full sun
Part Used: Leaves, seed
Taste: Very good
Method of preparation: Leaves steamed or boiled, leaves raw in salads, seeds for condiment.
Storability: Decent. Blanch and freeze.
Ease of growing: Easy