Some mustards have a strong flavor and some do not. You need to check out some different varieties so you can find the perfect one for your taste buds.
You can start mustard indoors or directly sow it outside.
Outdoor Sowing Tips: 1) In order to germinate, mustard seeds prefer soil temperatures between 50℉ and 70℉ just like arugula. Typically, this means sowing early to mid spring and late summer around Pittsburgh, PA.  2) Mustard seeds should be planted 1/4″ deep. 3) The distance for full grown mustard typically varies between 6″ and 12″. As for square foot gardening, put 4 plants per square foot which provides 6 inches of space. For baby mustard greens, plant the seeds close together.
Indoor Sowing Tips:  1) Sow the seeds in seed trays under grow lights. 2) Transplant in the grow room once the mustard seedling has two sets of true leaves and transplant them outside once there are a few more leaves. I usually start my mustard seeds indoors around 6 to 8 weeks before I transplant them. Don’t forget to harden off the seedlings before transplanting. 3) Use the spacing noted above.
Growing Tips: 4) Keep the seedlings and plants moist but not soggy! 5) Depending on your soil, you may need to give your mustard a little boost of nitrogen. 6) Since slugs may attack mustard, I use Sluggo Plus to get rid of them. Since mustard is a member of the Brassica Family, interplant mustard between the other members.  8) I am always ready for crazy temperature swings which means I have my garden fabric and hoop tunnels ready to go before I plant. 9) Mustard is a cold tolerant veggie that enjoys the spring and fall weather and prefers outside temperatures below 70℉. 10) Also, mustard is great for succession planting and interplanting.
Mustard belongs to the Greens veggie category.
