May Night Salvia (Salvia x sylvestris ‘May Night’)

May Night Salvia, scientifically known as Salvia x sylvestris ‘Mainacht’ or ‘May Night,’ is a popular herbaceous perennial valued for its stunning deep purple-blue flowers and attractive, easy-to-grow nature. In this article, we’ll explore the botanical characteristics of this plant, discuss its benefits in landscaping, and share design ideas and maintenance tips.

I. Appearance and Characteristics

May Night Salvia belongs to the mint family (Lamiaceae) and is a hybrid of Salvia nemorosa and Salvia pratensis. Its spiky, densely-packed flowers bloom from late spring to early summer and can reach heights of 18 to 24 inches. The gray-green, lance-shaped leaves contrast beautifully with the vibrant flowers, making it a visually striking plant.

May Night Salvia (Salvia x sylvestris 'May Night')
File:Salvia x sylvestris May Night 2zz.jpg
Photo by David J. Stang
CC BY-SA 4.0

May Night Salvia is native to Europe and western Asia, thriving in full sun to partial shade. It prefers well-draining soil, with a pH range of 6.0 to 7.0. Although it tolerates drought, it performs best with consistent moisture during its growing season.

II. How to Grow and Care

Sunlight

Grow May night salvia flowers in an area with full sun; a south-facing location is just right for this plant. Make sure the plant will receive six hours of sun a day.

Temperature and Humidity

May night salvia flowers are best grown in USDA planting zones 4-8. May night salvia can withstand bouts of hot and dry weather, but it does not do well in high humidity.

Watering

Watering
May Night Salvia has a moderate watering requirement. It prefers to be watered deeply but infrequently, allowing the soil to partially dry out between watering. Overwatering should be avoided as it can lead to root rot.

Soil

May night salvia needs well-draining soil to be a successful plant. Add sand to the soil to help it drain well.

May Night Salvia (Salvia x sylvestris 'May Night')
Salvia x sylvestris May Night 0zz
Photo by David J. Stang
CC BY-SA 4.0

Fertilizing

May Night Salvia prefers a well-draining soil with a balanced fertilizer, such as a 10-10-10 or 14-14-14. Avoid excessive nitrogen as it can result in weak stems. Fertilize in early spring and again in early summer for optimal growth.

Pruning

You will only need to prune older May night salvia. The stems will become woody as they age.

Propagation

May night salvia can be easily propagated with stem cuttings. May night salvia stem cuttings can be grown in either water, soil, or moist compost. Take these very easy steps:

  • Use a sharp, clean gardening shear to cut 2- to 8-inch long cuttings.
  • Place the stem in clean water or in clean, moist soil in a seedling pot.
  • It’s time to replant when roots are 3/4 inches long.

How to Grow From Seed

May Night Salvia (Salvia x sylvestris 'May Night')

It is also very easy to grow May night salvia from seed. Doing so eliminates the steps of watching for roots to grow in water or a seedling pot, then transplanting. Here’s how to grow the plant from seed:

  • Harvest seeds from spent blooms. Take a bunch of the spent spears and rub them to release seeds or manually take the tiny seeds from the pods. The seeds look exactly like poppy seeds.
  • You can directly seed into your garden by dropping the harvested seeds into the soil, but your plants will likely do the same without your intervention. Or, for better control of the seeds, sow them indoors about three months before the last frost of the late winter or early spring.
  • Press a few seeds into seed starting mix in a pot and keep moist.
  • Seedlings will appear in about two to three weeks. Keep pots on a sunny windowsill or under plant grow lights for 16 hours daily and keep in the dark for eight hours.
  • When seedlings have two pairs of leaves, they will need to become hardened off before transplanting them outdoors. Move pots outdoors in a sheltered space for a few hours every day for a week. Don’t leave plants outside overnight.
  • Plant outdoors in full sun, each plant a foot apart, and water.

Potting and Repotting

May night salvia does well in containers but they need to be large pots to hold about two to three years of growth. A, 8- to 10-inch pot with about an 8-inch depth may be fine. Pots must have enough drainage holes so the plant will not suffer from waterlogged soil. However, the soil also needs the addition of a gravel/mulch mixture to help prevent drought. After a few years of growth, you will need to divide the salvia and repot into new, larger pots (or outdoors).

Overwintering

If you planted May night salvia in containers, bring them inside for the winter months if you live outside the plant’s hardiness zones.

May Night Salvia (Salvia x sylvestris 'May Night')

If the plants are in the ground, and you live within the correct hardiness zones, remove dead foliage and cover the plants with a layer of mulch once the ground freezes. Mulch can be raked away in the spring.

Pests and Diseases

Common Pests & Plant Diseases

Scale insects, leafhoppers, spider mites, aphids, and whiteflies have been known to attack salvias. If any of these insect pests bother your plants, spray them with neem oil, a popular product for organic pest control.

Fungal infections can cause stem and root rot, powdery mildew, and Botrytis blight, specifically when May night salvia experiences extended cool wet weather. Typically, fungal infections occur when the soil is not well draining or plants do not have enough air circulation.

Common Problems

May night salvia needs very little maintenance to thrive. However, there are two main problems: legginess and leaf damage. Here’s why:

Legginess and Flopping Over

May night salvia can become leggy or floppy for many reasons:

  • It needs to be cut down or divided to encourage new growth because there’s not enough air circulation between clumps.
  • It is not getting enough sunlight.
  • It could be overfertilized—this plant is a very light feeder and doesn’t even need to be fed.

Leaf Damage and Discoloration

The leaves of May night salvia can become damaged, discolored, deformed, and lesioned due to feeding pests, including:

  • Foliar nematodes, also known as soilborne parasitic worms, can cause lesions on the foliage leading to leaf death and possibly bud malformation. Remove damaged plants and avoid overhead watering.
  • Leafhoppers suck sap from the underside of leaves, which then turn brown. Insecticidal soap can remedy this pest.
  • Scale insects also suck sap from leaves, then secrete a waxy substance onto the leaves to kill them. Foliar spray (diluted fertilizer) helps with large infestations.
  • Whiteflies attack the underside of the leaves, as well, and also leave behind a waxy film. Neem oil applied under the leaves can help.
  • Spider mites turn leaves light yellow and leave fine white webs on a leaf’s underside, which can result in the stunting of the leaf’s growth. Use horticultural oil to handle large infestations.

III. Uses and Benefits

May Night Salvia (Salvia x sylvestris 'May Night')

There are several ways to integrate May Night Salvia into your landscape, depending on your preferences and garden style.

  • Creating a Perennial Border

May Night Salvia works well as a mid-height element in a perennial border, adding depth and vertical interest. Plant it alongside other perennials with similar growing conditions, such as Russian Sage, Catmint, or Coneflowers, to create a cohesive design.

  • Adding Height to a Rock Garden

In a rock garden, May Night Salvia can provide an eye-catching vertical element among low-growing alpine plants and decorative rocks. It’s a versatile plant that can adapt to various soil types, making it a perfect addition to this garden style.

  • Complementing with Other Plants

May Night Salvia pairs beautifully with other plants, creating stunning color combinations and textures in your garden. For a harmonious color scheme, consider planting it alongside soft yellows, such as Coreopsis, or pale pinks like Echinacea. Alternatively, make a bold statement by pairing May Night Salvia with contrasting colors like orange Daylilies or red Kniphofia.

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