It brings tears to my eyes - a young colleague has started her first vegetable garden, including onions.

Her interest in growing her own onions, tomatoes, peppers and other veggies reflects a national trend. In a recent survey by the Garden Writers Association Foundation, 39 percent of consumers planned to buy vegetable or fruit plants this year, ahead of both annuals (35 percent) and perennials (31 percent).

Yellow, purple, Spanish, leeks, shallots, scallions, pearls … onions are among the easiest vegetables to grow. Pungent or sweet, onions are a staple in cooking, and, I ask you, what could taste better than beer-battered fried onion rings?

Getting onion sets, plants or seeds in the ground is one thing, but figuring out how to care for onions and when to harvest has my friend a little stumped.

Onions are photoperiodic plants, which means growth or bulb formation is linked to day length, as well as temperatures. Cool, early spring days promote root development and as days lengthen, bulbs grow. There are short-day, intermediate and long-day varieties. Long-day varieties are considered the best choice for Iowa gardeners and require 14 or more hours of daylight to form bulbs.

Proper care includes making sure plants receive 1 inch of water each week. At summer's zenith, when days are particularly hot and dry, water onions weekly. Hand-pull weeds or mulch to reduce weeds around the shallowly rooted plants.

According to Iowa State University horticulturists, the "perfectly grown" onion has 13 leaves and 13 rings of scales around the bulb. Leaves correspond to the rings, and the larger the leaves, the larger the rings.

If onions are grown from sets or plants, the home gardener can begin harvesting green onions within 30 days (add 20 or so more days if grown from seed). Depending on variety, onions mature in 90 to 120 days. When leaves begin to dry up and fall over, it's a sign onions are ready to harvest. You can leave the onions in the ground for another week or two, but no longer to prevent rotting.

To harvest, pull onions or dig them up, leaving foliage intact. Dry bulbs in the sun for a single day, then trim leaves 1 inch or so from the bulb to allow the neck to dry. Separate the onions you want to store from the onions you plan to eat.

Cure onions before storing. This is important or onions will rot. Choose a warm, well-ventilated place (a garage or porch) out of the sun. Spread out onions, making sure they don't touch. If you cover the onions, use an old cotton sheet, not plastic or canvas tarps, which trap moisture. Remember to turn onions several times during the drying process, which can take three weeks. Onions must be bone-dry for storage; moist onions will rot.

Then hang onions in mesh bags in a well-ventilated area to dry some more before storing.