If you've prepared your soil well, no fertilizing should be necessary. Always go easy on nitrogen, which can produce lush tops at the expense of bulbs. New growth from the center will stop when the bulbs start forming.
Egyptian onions, chives, and shallots require slightly different cultivation from regular onions. Here are some guidelines for growing these onion relatives:
Plant Egyptian onions in fall throughout the country; harvest some in spring as green or bunching onions. In midsummer or fall, miniature bulbs will form at the stem tip, where most onions form flowers. Pick these tiny bulbs when the tops begin to wilt and dry. Use them fresh or store in the freezer.
Plant chives and garlic chives in early spring in rich soil. They will tolerate partial shade put prefer full sun. Seeds are very slow to germinate, so most growers prefer to plant clump divisions, which can be harvested after 2 months. Space the clumps, each of which should contain about six bulbs, 8 inches apart.
Cut the grasslike, hollow tops frequently to maintain production. The pom-pom-like lavender flowers are very attractive, but always remove the spent flowers to reduce the chance of rampant self-seeding. Dig up, divide, and replant every third year. Transplant to containers and move indoors for winter harvests. Chives are almost as good frozen as they are fresh.
Shallots, a favorite of French chefs, have a blue-green stem that's used when young. In addition, it has a gray, angular, mild-flavored bulb that's related to the multiplying onion and is used like a mild-flavored garlic. Shallots will tolerate all but the most acid soils, but dig the earth deeply because the plants put down 8-inch-long feeder roots. However, they have no lateral roots, so space them just 2 to 3 inches apart.
Propagate shallots by dividing bulb clusters. Each clove, in turn, will produce four to eight new bulbs. In February or March, plant them 1 inch deep, barely covering the tip of the clove. Keep the soil weed free and slightly moist, but don't fertilize. In early summer, draw the soil away from the bulbs. Harvest shallots as green onions at any time. Cutting the tops off near soil level will produce new tops, and such harvesting actually increases bulb production. Bulbs mature in about 5 months. Pull and store like onions.