Onions – scallions, bulb and gourmet cipollini – thrive in cool-season gardens here. Plant bulb onion seeds now, making sure to select short-day varieties ideal for southern regions like San Diego. Some tried-and-true varieties are yellow ‘Grano’, ‘Granex’ and ‘Texas Super Sweet’ and red ‘Desert Sunrise’ and ‘Red Burgundy’. Onion sets (small bulbs) are good for a quick crop of green onions but they are not the best varieties for bulbs in our area. Try monthly successive plantings of scallions for fresh green onions winter into spring. Choose a sunny site, water and feed these shallow-rooted plants regularly to encourage strong top growth and bigger bulbs. Harvest scallions when tops are a foot or so long; harvest bulbs in summer when tops yellow and fall over.