The tropical mint Salvia divinorum presents several challenges to the gardener. Diviner's sage seldom sets seed, and seeds show a very low germination rate. Seedlings rarely survive long. The usual and more reliable propagation method involves rooting cuttings of stems and leaves.
Purchase healthy cuttings or take sections from the tops of vigorous side stalks. Include four to six sets of leaves and at least 4 inches of stalk. If nodes are visible, cut the stalk below a node. Salvia divinorum naturally propagates when heavy side stalks bend over, rooting where the stalks touch ground. In humid air, nodes form on stems and may already produce small roots.
Fill a glass with 2 inches of clean water and place the cutting in the glass stalk down. If starting more than one cutting, use a separate glass for each plant. Leaves may wilt over the first few days, but the cuttings should recover quickly. Roots form after two or three weeks. Keep the cuttings indoors and out of direct sunlight while the roots develop. Add water to the glass to maintain the original 2 inches of depth.
Fill a clay pot with potting soil. Use potting soil that's rich in humus and amended with sand and perlite. Salvia divinorum requires moist but well-drained soil. Dense or wet soil puts the plant at risk for root diseases. When the cutting's roots are 1/4 to 3/4 of an inch long, transplant to a small clay pot. Plant the stem to the same soil depth as the water level in the glass---about 2 inches. Cover the plants with a plastic bag or upturned glass jar for the first two or three days to reduce transplant shock.
Place the cutting where it receives no more than three or four hours of sunlight daily, or grow the Diviner's sage under artificial florescent grow lights. Low humidity could cause deformed leaves. Best growth occurs in light shade, 50 percent humidity and temperatures between 60 and 80 degrees F. Mature Salvia divinorum requires a large pot at least 12 inches deep to give roots plenty of growing room.
Fertilize Salvia divinorum with houseplant food about a month after transplanting to pots. Use half the amount recommended by the manufacturer. Follow the feeding schedule outlined on the package and increase to a full dose after two months.