Propagation Of Dianthus

A satisfying aspect of growing dianthus is the ease with which they can be propagated. Garden pinks look great when several varieties are grown in adjacent clumps that spread and mingle to form a raised carpet of color. In a few seasons your dianthus will have self-seeded readily, with an interesting blending of color as varieties hybridize among themselves.

Seeds and sowing

The best germination rates are achieved when the seed of border carnations, annuals and pinks is fresh. The seed is held in an upright capsule formed inside the dried calyx. When ripe, it's easy to shake out. Seeds need no special treatment before sowing, though their coating is brittle and they should be handled carefully. If you are gathering your own seeds and want to store them for later use, ensure that they are kept dry and cool in a dark place. Pinks can be sown directly into open ground in late spring, though you will get better results from early indoor sowing. Cultivate the soil so that its texture is finely crumbled and consistent. Sow the seeds thinly, barely cover with a light layer of fine soil and keep it moist until the first sign of green appears above ground. When the seedlings are large enough to handle, thin them and protect from disturbance by birds. For gardeners who want numerous plants, it makes more sense to start them indoors and transplant them into the garden later as small, established plants to fit in with a landscaping plan. Indoor sowing means you are less dependent on favorable weather when the tiny seedlings are vulnerable to wind and cold. They can be sown under warm cover (60-70�F/15-20�C) in winter. Many pinks, planted from seeds, will flower in the same season. Seed is best sown in trays of seed-raising mixture and lightly covered by fine vermiculite or a fine layer of sand. Mist with water and place the tray in a warm position. The soil mix must remain moist to ensure germination, which can be rapid, with the first seedlings appearing within 4-5 days. They should be grown in good light from the outset to ensure compact, sturdy seedlings. If grown in shade, they stretch and are much more prone to damage and damping-off (the failure of the seedling caused by fungi). Well-spaced seedlings, which allow for good air circulation, are also less likely to succumb to damping-off. The first leaves to appear are cotyledons-i.e., seed leaves-that bear no resemblance to the mature grasslike leaves. When the true leaves appear, the seedlings are ready for pricking out or transferring to more spacious living quarters, usually a deeper tray. The seedlings are very delicate at this stage, and they need careful handling. Loosen the soil before attempting to dislodge them and hold them between thumb and forefinger by the seed leaves. Firm them into the soil to avoid air pockets and continue to keep the planting mix moist. When the plants are about 2 in (5 cm) high, they are ready to be transferred to small pots. The young plants are ready for transplanting into permanent positions when the root structure has grown out to the limit of the mix in the pot, probably when they are about 6 in (15 cm) high. If you live in an area with a mild climate, it is best to plant out in the fall, but if you live in an area with a harsh winter, wait until the spring. If raised in a greenhouse, seedlings should be hardened off (acclimatized) by placing their pots in a sheltered, outside position for a few weeks prior to planting. Seeds of annual carnations will germinate in temperatures as low as 40�F (4�C), though it happens more quickly in warmer conditions-two to three weeks at 65�-75�F (18-23�C)-and they will flower approximately 28 weeks from planting. Sow seed in late winter-the earlier you start them off, the earlier they will flower. The seedlings should be potted into shallow trays and planted outdoors in an open sunny situation once all danger of frost has passed. All their side shoots turn into flowering shoots in the season of planting and often they will continue blooming until the first frosts of fall, though it is essential to deadhead them from time to time.

Vegetative propagation

Layering: Border carnations were traditionally propagated by layering, garden pinks more rarely. Layering involves partially cutting the stem of a shoot and fastening it into the ground while it is still attached to the parent plant. This encourages roots to form at the cut node (or joint) in the stem. The best time for layering is midsummer, or as soon as the plants have finished flowering and before the stems become brittle in autumn. Choose a healthy parent plant and select a robust, long shoot as the potential layer. Remove its lower leaves, leaving at least five pairs of leaves on the top part of the shoot. You will notice that the nodes on the upper part of the stem are closer together than near the base of the shoot. It is one of these upper nodes that should be split. Loosen the soil around the base of the mother plant and create a small pocket of planting mix that contains light soil and sharp sand. This is where the layer will be inserted in the ground. Use a clean, sharp, pointed knife-one with a thin blade will make the job easier. Prepare the shoot to be layered by slicing the stem lengthwise through a node and forming a tongue. The stem should be slit for approximately 1/2 in (1 cm) two nodes below where the leaves were stripped off. Fasten the tongued section into the ground with a wooden peg or a hooked piece of wire that will not cut into the stem. Firm the soil around the pegged layer and water well, making sure it never completely dries out while the roots are forming. Layers take from four to six weeks to form roots, at which stage they can be severed from the mother plant. Once the umbilical cord is cut, leave the rooted layers in place for several days to stabilize before removing them. The newly planted layers will need protection from full sun until they are well established. Several layers can be taken from one mother plant, provided it is large enough.
Cuttings: All dianthus can be propagated by cuttings, though border, spray and perpetual-flowering carnations root more successfully when bottom heat is provided. As with layering, the best time of the year to take cuttings of carnations and garden pinks is late summer when there is sufficient warmth and enough time for the cuttings to establish before cold weather arrives to inhibit their growth. Cuttings for border carnations and pinks are best taken from non-flowering side shoots and should be short and sturdy-no more than 4 in (10 cm) long-and the healthier the mother plant, the better the quality of the cuttings will be. It's tempting to take cuttings on the spur of the moment-to relieve the monotony of a weeding spree or when wandering in the garden admiring a plant with a friend, but plan ahead and your success rate will be greater. Water the mother plant the previous day and cuttings will be more succulent, more inclined to form roots easily. If you take the trouble to fetch a sharp knife or secateurs, there will be less risk of damage to the parent plant. Where only a few new plants are required, the cuttings may be planted directly into the garden, but it is easier to take care of developing plants when they're set out near your working area in trays or pots. Strip off the lower two pairs of leaves from each cutting before inserting them in the planting mix. The following media are all suitable: clean sand, a mixture of equal parts soil (or compost) and sand, or equal parts perlite, sand and peat. The cuttings need to be inserted about 2 in (5 cm) apart. Place the cuttings in a shaded area, keep the planting mix moist and roots should develop in four to six weeks. Roots will form more quickly in warm humid weather. Damping-off can be a problem, not only with seedlings but also with cuttings. Sterilized soil helps to prevent this disease. Once cuttings have rooted, those set out in pure sand will need some nutrients. Either repot them in potting mix or compost or plant them out in permanent positions in the garden. When the ground has been prepared outdoors, that is dug over, weeded and fertilized, dig a small hole and if your soil is poor or very gravelly, prepare a "nest" of compost and soil to encourage the new plant to develop strong roots. This is a good time to incorporate some slow-release fertilizer if you are using a homemade potting mix. Fill the hole with water. When this has drained away, it's time to plant. The cutting should be planted at the same level as it was in its pot and the soil needs to be firmed around it to eliminate air pockets. In areas where frosts are persistent, the young plants will be happier in pots where they will receive some protection, such as in a cold greenhouse.
Root divisions: Another vegetative method of propagating pinks is from rooted sections. This is most useful when you have made the decision that some old, ragged, but still cherished plants are really past their prime and have to go. You love the flowers, you've left it too late to take good cuttings and you're afraid you will lose them. Pull the plants apart as you take them out and trim the foliage. Tidy-up portions where there are healthy roots still attached and replant them.

From Mick Hogan - Feb-04-2013: I'm new to taking cuttings, but in September last year I took about 12 Dianthus cuttings and potted them up in plastic pots of 50/50 compost and grit. They have been in my garage near the window and have rooted so I intend to plant them out in the garden when the bed is prepared and the frosts have gone. Wish me luck !