Black and Blue Salvia (Salvia guaranitica ‘Black and Blue’) is a beloved plant, recognized for its striking deep blue flowers and contrasting dark stems. It brings vibrant color to gardens and attracts pollinators like hummingbirds, bees, and butterflies. Propagating this plant offers several advantages, including expanding your garden, sharing with friends, or simply ensuring you have more of these beautiful plants without additional cost.
Timing for Propagation
The optimal time to propagate Black and Blue Salvia depends on the method chosen. Late summer is ideal for cuttings, as stems are firm but flexible. Taking cuttings too early can lead to wilting in high heat, while waiting too long might prevent root establishment before cooler temperatures arrive. For division, spring or fall, when the plant is dormant, offers the best chance for success.
Propagating from Cuttings
Propagating Black and Blue Salvia from cuttings is an effective method, ensuring new plants are genetically identical to the parent.
Taking Cuttings
Select healthy, non-flowering stems, about 2-3 inches (5-8 cm) long and semi-ripe. Using sharp, clean pruning shears or a knife, make a cut just below a leaf node, where growth cells promote rooting. If collecting multiple cuttings, place them in a glass of water or a plastic bag to keep them fresh and hydrated.
Preparing Cuttings
Remove leaves from the lower few inches of each cutting. This prevents rotting and directs the plant’s energy towards root production. If the remaining leaves at the top are large, cut them in half to reduce moisture loss. Dipping the cut end into a rooting hormone powder or gel can encourage faster, more successful root development.
Rooting Cuttings
Use a well-draining medium, such as a mix of perlite, vermiculite, and potting soil, or a gritty compost. A common ratio is 70% perlite/vermiculite to 30% potting soil. Plant the prepared cuttings into small pots, ensuring at least one leaf node is buried. You can place several cuttings in one pot.
Water the cuttings thoroughly and cover the pot loosely with a clear plastic bag or place it in a propagator. Maintain a consistent soil temperature between 68 to 73°F (20 to 23°C) and provide bright, indirect light. Roots form within 2 to 4 weeks.
Propagating by Division
Black and Blue Salvia spreads through its roots and rhizomes, making division a viable method for propagation, especially for mature plants. This technique is suitable when a plant has become overgrown or when you wish to create several new plants.
To divide, carefully dig around the mature plant, lifting the entire root ball. Gently loosen the soil around the roots to expose them. The root ball can then be pulled apart or, if dense, cut into smaller sections using a sharp knife or spade, ensuring each section has both shoots and a good quantity of roots. Replant these divisions promptly into their new locations, ensuring they are watered thoroughly.
Propagating from Seeds
While it is possible to propagate Black and Blue Salvia from seeds, this method is less common and has limitations. Unlike cuttings or division, plants grown from seeds may not be true to the parent plant due to cross-pollination. Seed germination can be slow and unreliable for this salvia variety.
Sow seeds just below the soil surface in a quality seed-raising mix. Salvia seeds often require light to germinate, so a very thin covering of vermiculite is suitable. Maintain consistent moisture and a soil temperature of around 70-75°F (21-24°C). Germination occurs within 5 to 20 days.
Aftercare for New Plants
Once your Black and Blue Salvia cuttings have rooted, or divisions and seedlings are established, aftercare is important for successful growth. Once rooted, young plants can be transplanted into small pots. Gradually acclimate these new plants to outdoor conditions by exposing them to increasing periods of sunlight and less humidity over several days.
When ready for their final location, whether in the garden or larger containers, ensure the soil is well-draining and the site receives ample sunlight, ideally at least six hours daily. Water newly transplanted salvias deeply and regularly until they are established, allowing the soil to dry slightly between waterings. A balanced slow-release fertilizer can be applied in spring to support vigorous growth.
Common Propagation Issues
Some issues can arise during the propagation of Black and Blue Salvia. Wilting of cuttings is a common concern, often indicating insufficient humidity or excessive moisture loss. Providing a humid environment with a plastic cover or propagator helps maintain the necessary moisture. Overwatering can lead to rotting. Ensuring the rooting medium drains well and is not constantly saturated helps prevent this.
Lack of rooting can occur if the cutting material is too woody or too soft, or if the environmental conditions are not optimal. Using semi-ripe cuttings and maintaining consistent warmth and indirect light can improve rooting success. New plants may appear leggy after rooting; this can be addressed by providing sufficient light and pinching back the growing tips to encourage bushier growth. If cuttings fail, it is beneficial to evaluate the stem selection, cutting preparation, and environmental controls for future attempts.