Start with broccoli. Clemson Cooperative Extension lists it at 8 to 10 days to harvest, the shortest window on its whole crop list. That harvest time is the case for the pick, and it is the one thing beginner microgreens need going for them. Sow a second tray of pea or sunflower beside the broccoli. The two seed sizes want different sowing rates, and you may as well learn both at once.
My first broccoli tray came off the shelf on day nine, cut and eaten while the pea tray beside it was still filling out. Same shelf, same bulb. The kitchen holds near 65°F (18°C) through winter. Those peas caught up six days later, which sits inside the 10 to 15 days the same crop list gives them.
The rest of the brassica family runs on the same clock. A separate extension guide puts radish, arugula, cabbage, kohlrabi and mustard at a cycle of 7 to 8 days at the outside. That is a day or two under the broccoli figure. The two numbers come from different crop lists, so read them as a range and not a promise. Neither source says these crops fail less often than the slow ones. They finish sooner. That short window is the whole reason beginner microgreens lists lean on the brassicas, and a tray you can cut in a week hands you a second sowing inside the same month.
Days to harvest is the only ranking these crop lists hand you, so it is the one to use while you sort out the easiest microgreens to grow. The spread runs from 8 days at the quick end to 21 at the slow end, which is the gap between a sowing every week and a sowing every three weeks.
Seed lists for microgreens run long. Arugula, basil, beans, beets, cabbage, celery, chard, cilantro, fennel and mustard all sit on the same page as the quick crops, and a first-timer reads that as ten equal options. They are not equal on time. Buy two packets for the first month and add a third once you know what a finished tray looks like.
Set your light before you sow a single seed. A simple fluorescent bulb sitting about 4 inches (10 cm) above the seedlings keeps them from going leggy, and that height matters more in a dim winter room than the bulb you buy. Raise it as the tray fills in.
Sowing rate does the rest of the work. Large seed goes down at about 2 seeds per square inch, which puts peas half an inch to 1 inch (1 to 3 cm) apart with room around each one. Small brassica seed goes up to 12 seeds per square inch, packed much closer, and that density is what fills a broccoli tray corner to corner. Scatter it thinly by hand and check the tray under a light before you walk away.
If you have room for one tray, make it broccoli. The fastest growing microgreens hand you something to cut while a slow crop is still sitting in its tray. You pick up watering and light height in eight days instead of three weeks. Sunflower earns the second tray for a different reason. Big seed is easy to place by hand. You can see what you sowed, and you can fix a thin patch before the tray ever goes under the bulb. Leave beet and nasturtium for a later round, once your beginner microgreens routine is steady.
Read the full article: Microgreens: What Science Says and How to Grow
