If you're looking for a way to add punch to your summer border, this bold, little-known bulb from South Africa may be the answer. Stout, 4 feet spikes of nodding, sweet-scented white flowers rise above clumps of strap-shaped, 2- to 3 feet-long leaves. The summer show is so grand that a half-dozen bulbs can dominate a border. Hardy to about 10F. Where winters are colder, dig bulbs in fall and store over winter as you would gladiolusthough summer hyacinth does bloom best when left undisturbed. Plant bulbs 6 inches deep and 1 feet apart in moist, well-drained soil that contains lots of organic matter.