Growing Border Carnations

Descended from Dianthus Caryophyllus, which is still to be found growing wild around the Mediterranean, the border carnations' natural habitat is rocky limestone, impoverished soil, where its long roots penetrate deeply into the soil.

Border carnations can be grown in the open in the garden or if you are showing under glass.

Looking to Dianthus Caryophyllus, border carnations prefer an environment where they are not shaded, there is plenty of free flowing air, the soil is well drained and is not acidic.

Garden Culture

Heavy soils will benefit from the introduction of sharp sand and grit to increase draining. Well rotted manure or compost should be added when the bed is dug and a light top dressing of lime should be added.

Lighter, sandy soils will need a moderate dressing of well rotted manure and a light dressing of lime.

Before adding lime, buy a soil acidity testing kit and find out what PH your soil is to inform how much lime may or may not be needed.

Raised beds though helpful are not essential but they can help with drainage.

Plants can be bought from specialist nurseries such as Allwood's and are usually available from September to October and from March to April.

Autumn planting is preferred as it allows plants to become well established before winter. If planting them in the position they will remain in, plant them 18 inches apart.

As the weather become warmer and the plants  show signs of growing, a light dressing of fertiliser such as John Innes Base fertiliser can be hoed in.

When the plants begin to grow a flower spike ready to flower in June and July a three foot cane should be added to support the main stem. A light dressing on potash can be added.

The flower spike will have a crown bud, followed by a number of subsidiary buds. Leaving the main crown bud, remove the next bud and leave all the other buds. In short remove one bud only - the one subordinate to the crown bud.

Greenhouse Culture

Border carnations can be grown in greenhouses in pots of in a bed within the greenhouse. Growing a border carnation in a bed in a greenhouse is the same as growing then in the garden.

Remember they are hard plants and want lots of free flowing fresh air and light and the main reason border carnations are grown in a greenhouse to the produce show blooms that are protected from the elements.

Border carnations grown for exhibition are predominantly grown in pots. Plants should be potted though increasingly sized pots until they are finally growing in 8 or 9 inches pots.

Compost

John Innes Number 2 with about an additional third of peat and a quarter of sharp sand and grit. Lime stone chips placed in the bottom of a pot allow the plats to access lime. A little charcoal helps keep the compost sweet.

Border carnations though are fairly forgiving on composts are long as they are free draining and not acidic.

Propagation

Border carnations can be propagated from seed, from layering and from cuttings.

Seeds

Due to their mixed parentage border carnations are not true to colour if grown from seed. Seeds should be sowed when rip onto a free draining compost and covered with a little vermiculite.

Layering

Obtaining vigorous new stock of your adult plants can be done through layering in July by selecting the strongest, disease free shoots.

Water well the plants being layered the day before.

Layering consists of stripping off the foliage from the shoot leaving six or eight pairs of leaves at the top of the shoot from a joint.

Using a thin, sharp knife insert it into the centre of the stem below the bottom pair of leaves left on the stem and downwards and out through the next joint or node to form a tongue leaving the shoot attached to the plant by the other half of the stem.

Remove around 2 inches of dil around the top of the plant and replace with a 50/50 mixture of peat and sharp sand.

The prepared layer is then gently pushed into the layering compost and pegged in place. The layer must be in an upright position with the cut sides of layer being in contact with the rooting medium. Each layer is then covered with more compost and sand to retain moisture and exclude light.

Layers should be kept moist.

Cuttings

Cuttings should be taken as any other cutting, dipped in rooting hormone put in a rooting compost and kept moist.

If you have a propagator, rooting modules are a great invention.

Stopping

Border carnations should not be stopped otherwise the plant will not bloom.

Pests

Border carnation pests are few, the worst is the Carnation Fly, that deposits its eggs on the foliage. The grub hatches out and bores its way into the leaves, leaving  a trail or grey patch. The fly is active from from early June until August. Leaves containing the maggot must be removed and destroyed and the maggot will eat its way through the plant or layer and kill it. Prevention measures can be taken by using systemic insecticides.

Thrips are a small fly that can suck the colour from a bloom leaving a white patch or patches.

Aphides. Will be got rid of by the use of systemic insecticides.

Red spider mite can be one of the most troublesome problems of greenhouse plants and houseplants. It can also attack garden plants during summer. It is a sap-sucking mite that attacks the foliage of plants, causing a mottled appearance, and in severe cases, leaf loss and plant death. Plants infested with glasshouse red spider mite show a fine pale mottling on the upper leaf surface. The underside of the leaves have many tiny yellowish green mites and white cast skins and egg shells. These are more easily seen with the aid of a x10 hand lens.

Red spider can be controlled with the systemic neonicotinoid pesticide acetamiprid (e.g. Bug Clear Ultra).

Natural controls include predatory mites Phytoseiulus persimilis and Amblyseius, a predatory midge (Feltiella acrarsuga) and a rove beetle, Atheta coriaria. 

Diseases

Border carnations are robust, healthy plants and only prone Mildew and Rust caused by damp conditions. Mildew can be cured by dusting the foliage and flowers with sulphur and Rust by spraying with a fungicide.