Clouds of yellow sulphur butterflies have been feasting on and swirling about the 'Purple on Purple' Mexican bush sage, creating a complementary feast for the eyes. Now topping out just over 4 feet tall at the Coastal Georgia Botanical Gardens in Savannah, it has simply been riveting. The 'Purple on Purple' is also a favorite nectar source for hummingbirds, and its bloom coincides perfectly with the Monarch butterflies' trek south.
The typical Mexican bush sage or Salvia leucantha is a prolific, blooming perennial -- or annual depending on where you live -- and loads up with countless fuzzy purple spikes supporting white flowers. But with 'Purple on Purple' there are no white flowers.
This time of year, the Mexican bush sage is really a must-have plant in everyone's garden. It is a short day bloomer. When the nights get longer and the days shorter it kicks into bloom like few other plants. It is perennial to zone 8, and with good winter drainage a spring return in zone 7 is often possible.
This short day floral extravaganza makes it the perfect companion to other short day bloomers like mums. Almost every color of mum would make a sizzling partner. It also makes a wonderful marriage with another short day salvia called the forsythia sage, Salvia madriensis. It, too, is a hummingbird magnet.
This is a creamy yellow, blooming salvia that reaches 5 to 7 feet tall, towering over the 'Purple on Purple' and creating a complementary color scheme that will have the neighbors green with envy. The forsythia sage is cold hardy to zone 7. Search out the variety 'Red Neck Girl,' which not only has burgundy red on the stem but also reportedly blooms earlier.
The ideal site is full sun, although a little afternoon shade is tolerated. The soil should be very well drained, so plant on raised beds or amend heavy soils with the addition of compost or humus. Well-drained soil may be the crucial factor encouraging next year's spring return farther north than expected.
While preparing the soil, incorporate 2 pounds of a slow-release 12-6-6-fertilizer per 100 square feet of bed space. Space the plants 24 to 36 inches apart, planting at the same depth they are growing in the container. Do not plant under streetlights or floodlights; remember, these bloom in response to the number of dark hours.
The 'Purple on Purple' is a prolific bloomer so take advantage of the opportunity to cut flowers for the vase.
The Mexican bush sage is still often sold generically, but 'Purple on Purple,' 'Midnight,' which also has dark purple flowers, and the dwarf 'Santa Barbara' with lavender flowers are choice selections. Typically the Mexican bush sage will easily reach 4 feet tall with an equal spread, while the compact forms reach less than 3 feet.
Norman Winter is director of the Coastal Georgia Botanical Gardens at the Historic Bamboo Farm, University of Georgia Cooperative Extension, and author of "Captivating Combinations Color and Style in the Garden." First Published October 18, 2013 8:00 PM