The term "bulb" is used as a catchall name to describe any fleshy underground root structure. The depths to which these types of bulbs are planted vary. Plants with corms, rhizomes and tubers--such as crocuses, irises and cannas--are typically planted within 4 inches of soil's surface. True bulbs on the other hand--such as tulips and daffodils--are typically planted a bit deeper, up to about 8 inches deep. For this reason, watering amounts for the different kinds of bulbs will vary; however, there are some general guidelines you can follow.
Water your bulbs with 1 to 2 inches of water immediately after planting them. You can do this with a sprinkler or hose, if desired.
Watch for the buds to first appear. This usually occurs in the spring or early summer. This is the time when you should begin watering your plants on a regular basis.
Water your bulbs weekly with about an inch of water, but only when rainfall does not meet this requirement. Ideally, use a soaker hose to prevent watering the blooms, which can cause them to droop and wilt quickly. Lay the soaker hose around the base of your plants and turn the spigot on slightly to water the plants slowly, which enables the water to soak in more thoroughly.
Stop watering your plant bulbs in the early fall.