Azure Blue Sage (Salvia azurea) is a perennial plant that blooms from summer to fall with showy bright blue flowers that bloom along a flower stem. Foliage emits a pleasant fragrance when leaves are rubbed. An excellent choice for a wildflower garden it thrives in full sun or partial shade in sandy clay or loamy soil.
I. Appearance and Characteristics
Salvia azurea, the azure blue sage, azure sage, blue sage or prairie sage, is a herbaceous perennial in the genus Salvia that is native to Central and Eastern North America.
Its thin, upright stems can grow to 6 feet (1.8 m) tall, with narrow, pointed, smooth-edged to serrated, furry to smooth green leaves, connected to their stems by petioles to 0.4 inches (1.0 cm) long. There are no basal leaves.
The blue flowers (rarely white), nearly 1⁄4 to 1⁄2 inch (6.4 to 12.7 mm) long, appear summer to autumn near the ends of their branched or unbranched spikes; their calyxes are tubular or bell-shaped and furry. Two varieties are known, Salvia azurea var. azurea (azure sage) and Salvia azurea var. grandiflora (Pitcher sage).
The stems of wild S. azurea tend to be long and unbranched, causing them to flop under the weight of their flowers. When grown in cultivation, the stems of S. azurea are sometimes cut back early in the growing season to encourage branching and slow the vertical growth of the plant to prevent lodging.
Throughout its range, it is found growing wildon roadsides, glades, prairies, savannas, fields and pastures. S. azurea prefers dry, sunny conditions in a variety of soils, including clay, gravel, and loam. In wetter conditions, the plant will still grow and bloom, but tends to lodge.
II. How to Grow and Care
Sunlight
Salvia azurea require full sun, which is generally defined as a minimum of six hours of direct sunlight daily. There are varieties that will also tolerate partial shade. They are facultative long day plants and flower induction occurs more rapidly under long days. They will flower under any photoperiod, but will flower quicker and better under long days.
Until plants become established, some protection from extreme winds and direct, hot sunlight may be necessary. Good air movement is also important.
Temperature
There are azure blue sage varieties from all around the world, although the majority of varieties originate from Central and South America. As may be expected, therefore, many azure Blue Sage species are tender with a fondness for warmer climates. However, there are also hardy azure Blue Sage species that can deal with temperatures that plummet below freezing.
Watering
Drought-resistant varieties of azure Blue Sage require little watering, even during the summer. They only need watering during periods of drought. However, some tender varieties and young plants should be watered regularly, about 2.5 cm of water every 7-10 days so that their soil does not completely dry out.
Soil
Salvia azurea can be grow in containers but grow best in garden beds. They don’t need rich soil, but they must have good drainage. In pots, a mixture of ordinary garden soil mixed with perlite allows water to drain rapidly. The soil pH should be 5.8 – 6.2.
When planting in garden, prepare the bed by turning the soil under to a depth of 6-12, inches removing any debris, and lightly raking as level as possible. The addition of organic matter (leaf mold, compost, well-rotted manure) benefits all gardens and is essential in recently constructed neighborhoods. Dig a hole twice the diameter of the container the plant is in. Remove the plant from its container and place it in the hole so the top of the root ball is level with the soil surface. Space plants 1 to 3 feet apart, depending on the variety. Carefully fill in around the plant and firm the soil gently. Water thoroughly and apply a light mulch layer on top of the soil (1-2 inches) to conserve water and reduce weeds.
Fertilizing
In rich or clay soils, azure Blue Sage requires no fertilizer. As a light feeder, azure Blue Sage will benefit from the addition of a little compost in poor soil. You can also add some slow-release fertilizer when planting. Take care not to add too much fertilizer, however, as this will cause them to grow too rapidly and flop over.
Planting Instructions
The majority of azure Blue Sage species begin flowering in the summer and continue flowering all the way through to mid-autumn. When growing from seed, azure Blue Sage should be sown early in the growing season like spring to ensure that plants have time to establish themselves and flower before the arrival of frosts, later in the year. You can sow the seeds directly in the garden or, for early blooms, sow seeds indoors and transplant the new plants into the garden in early spring.
However, if you have bought a potted azure Blue Sage, you can choose to plant it either during the spring or the autumn. Although autumn may seem to be an unlikely time to plant azure Blue Sage, this is, in fact, a brilliant time of year for gardeners to get ahead before the next growing season. Autumn is an ideal time for planting or separating sage, not only to extend the flowering season in your garden but also to provide the plant with the opportunity to establish a healthy root system before its winter dormancy, so it is ready to burst into life the following spring.
Be sure to give azure Blue Sage plenty of space when positioning it in the garden, allowing for its tall and colorful blooms. If you are planting a tender variety of azure Blue Sage, such as Salvia coccinea ‘Lady in Red’, it may be better suited to a container that can be easily moved to a sheltered position, to avoid frost damage during the winter. In addition, gardeners in cooler regions may also like to consider treating tender varieties of azure Blue Sage that prefer warmer climates as annuals, rather than as typical perennials.
Pruning
Trimming and pinching can be done early when a fall planting is done. Pinching 2 to 4 weeks after transplant in the fall can assist in building a plant that has a thicker form and also give you more flower spikes per pot. Trimming is not recommended when forcing plants in the spring or on plants that have been freshly planted in the spring from cooled liners.
Remove spent flower spikes to encourage flowering and prevent seed development. Pinching the growing tips of plants can encourage business.
Propagation
The plants can propagate by cuttings. Take cuttings in August or September, from vegetative (non-flowering) branches that are about 3 inches long. Remove the lower leaves and trim each cutting just below a node. You can either start propagating by placing them in water or by putting them in soil. If you opt for cutting propagation in water, just put the cuttings in a vase and add a few inches of water. When rooting cuttings in soil, dip the cut end in rooting hormone, then plant it in a moist potting medium. One good medium to try is a 70/30 mix of perlite/vermiculite and potting soil. After three weeks, cuttings should be ready to pot on.
Mulching
Keep weeds under control during the growing season. Weeds compete with plants for water, space and nutrients, so control them by either cultivating often or use a mulch to prevent their seeds from germinating.
Mulches help retain soil moisture and maintain even soil temperatures. For annuals an organic mulch of shredded leaves lends a natural look to the bed and will improve the soil as it breaks down in time. Always keep mulches off a plant’s stems to prevent possible rot.
Transplanting
The azure Blue Sage thrives when transplanted during the period of late winter to early spring (S1-S2), it’s the optimum time due to dormant growth. A location with well-drained soil and full sun exposure is ideal. Be gentle, as roots can be sensitive during transplanting. Remember, proper care leads to a flourishing azure Blue Sage!
Pests and Diseases
The most common insect problem to watch for is the two-spotted Spider Mite. A routine scouting program is recommended to ensure that Whiteflies, Aphids and other greenhouse pests don’t harm the plant as well. Foliar diseases should also be scouted to prevent Botrytis and Crown Rots.
