Soaring sunflowers  These sunny giants bring old-fashioned charm
and a bounty of edible seeds. Here's how to grow and harvest
them.   Spring's the time to shop for warm-season flowers, like
this 'Tarahumara' sunflower.  Thomas J. Story  Watching a tiny
seedling turn into a plant tall enough to tower over Shaquille
O'Neal in a single season can restore your sense of wonder.
Indulge your inner child by growing some old-fashioned, seed-
producing sunflowers this summer. The flowers are huge ― a foot
across or more ― and as simple as a child's drawing of the sun,
a circle of short yellow rays around a brown center. The reward
is the crop ― enough sunflower seeds for both you and visiting
songbirds to enjoy a feast.  One of the tallest sunflowers on
the market is 'Sunzilla' (4), a new sturdy-stemmed hybrid that
grows up to 16 feet tall. Other varieties in the 10- to 15-foot
range include 'Giganteus' (3), 'Kong' (1, 2), 'Mammoth Russian'
(1, 3), and 'Paul Bunyan' (1). Two medium-size varieties are 7-
to 10-foot 'Tar