The new generation of Altheas (Hibiscus syriacus) is awesome.

This tough old shrub, also known as "Rose-of-Sharon", has been a mainstay around rural and urban homes throughout Oklahoma for as long as I can remember.

A large 12 footer with pale blue flowers grew by the front porch of my great grandparent's farm home when I was a boy. It was one of the few summer flowering shrubs that would tolerate the wind, heat and droughts of Central Oklahoma. The leggy, vase-shaped old specimen always seemed to be in bloom, even when summer fields and meadows were brown and scorched for lack of rain.

The Rose-of-Sharon from past generations was a worthy landscape shrub. Sure, it was a tad leggy and it shed lots of leaves when stressed by summer weather. But, it was a survivor and it bloomed during a season (July and August) when little else bloomed.

Time has been kind to Rose-of-Sharon. Old varieties were good; new varieties are great. Their form (shape) is better, more rounded and less leggy. They bloom over a longer period, late June to October in my Tulsa garden. And their flowers are larger and come in richer colors.

The new U.S. National Arboretum varieties are particularly exciting. Four of the best include:

Rose of Sharon 'Aphrodite'

‘Aphrodite’ – this multi-stemmed, low branched variety grows 8 to 9 feet tall and wide. It covers itself with large, rich pink flowers 4 to 5 inches in diameter from June to early October. Each robust pink flower has a dark red center (eye). The color combination is very nice.

Rose of Sharon 'Diana'

‘Diana’ – This new triploid with large pure white flowers and waxy dark green foliage is my favorite. It too faithfully blooms mid summer to fall. Unlike other varieties, however, its big white flowers remain open at night.

‘Helene’ – This triploid also produces large white flowers. But unlike ‘Diana’, its flowers come with a reddish blush near the base. It seems to flower particularly well toward the end of summer.

‘Minerva’ – You can’t help but admire Minerva’s big 5 inch diameter flowers. They are rich lavender with a prominent dark red eye. It made an outstanding floral display in a mixed shrub border in my garden last summer.

Old and new Rose-of-Sharon varieties transplant well from containers throughout summer and early fall. They thrive in virtually all soils and prefer full sun for maximum flower production. Moderate to heavy pruning in early spring maintains a tight and tidy shape with lots of flowers.