What's big, beautiful, and a complete showoff in sunny summer gardens? Come to think of it, lots of plants could fit that description, but we were thinking of 'Sunvilla Giant Red' mandevilla. A fast-growing tropical vine with large red trumpet-shaped flowers and lush glossy green leaves, this variety can grow 15 to 20 feet tall, latching onto trellises, arbors, or any other support that's tall enough. If it runs out of room, 'Sunvilla Giant Red' will simply cascade downward. Sadly, the Pacific NW is too cold for this South and Central American native, so enjoy it as a summer annual. Determined gardeners may bring it indoors when the temps drop down into the 50s, cutting back significantly on water to prevent root rot, then bringing it out again when the weather warms.