Brilliant spikes of purple-blue flowers from summer through fall are the main attraction of "May Night" sage (Salvia nemerosa "May Night"). Drought tolerance, deer resistance, bee and butterfly attraction and easy care are other qualities that made this plant the Perennial Plant Association's 1997 perennial of the year and a garden workhorse from U.S. Department of Agriculture hardiness zones 5 through 11. Keep the flowers coming past early summer and the plant's form compact with judicious pruning.
"May Night" is a plant of many names. Apart from the most accepted scientific name S. nemerosa, it is sometimes called S. × sylvestris or S. x superba. It's cultivar and common names also include "Mainacht" and meadow or hardy sage. Whatever it's called, the plant grows to about 18 inches tall and spreads 24 inches wide, forming clumps that can be divided. The flower spikes rise from rosettes of aromatic, dark green basal foliage -- the leaves immediately above the crown of the plant -- on short stems with lance-shaped leaves arranged in pairs directly across from each other. They need full sun and well-draining, slightly acidic soil, with a pH from 5.5 to 6.4.
The small individual flowers on "May Night" open from the bottom of the spike up. As the flowers at the tip of the 6- to 10-inch spikes fade, snip individual stems away just above a pair of leaves that has small flower buds emerging from the joint, cutting between where the leaves emerge from the stem and the stem itself. These grow into lateral branches that produce new, smaller spikes. Trimming away flower spikes alone is called deadheading and is best done before the flower sets seed. Cut the plant down to its basal foliage when this bloom cycle is done to stimulate new growth and flowering until frost. Cutting the flower off while in bloom -- "May Night" performs well in flower arrangements -- can also extend bloom.
"May Night" is fairly compact compared to common S. nemerosa, but older specimens tend to flop open, revealing the center of the plant, as the growing season progresses. Dividing the plant in early spring is one option, but these sage plants can also be cut back by half, or even back to basal growth, in late spring to encourage stronger stems and a more compact shape. This delays initial bloom for several weeks, and the plants may begin to bloom at a lower height. The University of California Marin County Master Gardeners website notes that the young leaves from these spring trimmings can be used fresh in salads or dried for use in potpourri.
In mild climates where the crown of the plant is unlikely to be damaged by severe cold, cut the stems down to the ground before winter sets in. The hardy plant is unlikely to need special treatment from frost, but if temperatures occasionally dip below 20 degrees Fahrenheit, cover the crown of the plant with a light mulch until late winter or early spring.
- Proven Winners: "May Night"
- Purdue University Horticulture: Salvia "May Night" Chosen as 1997 Perennial of the Year
- University of California Marin Master Gardeners: Plant Guide -- Salvia Nemerosa "May Night"
- Fine Gardening: Salvia x Sylvestris "May Night" (Meadow Sage)
- The Well-Tended Perennial Garden; Tracy DiSabato-Aust
- Parker County Master Gardener Association: Frequently Asked Questions (FAQ)
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