Green gardening: growing border carnations

October 9, 2015

To many people, the word 'carnation' conjures up the florist's flower, available year-round, but there are other forms that are not as demanding to grow. Here's a guide to border carnations:

Green gardening: growing border carnations

A bit of history

Carnations have been cultivated since the mid-15th century.

  • By the early 18th century, amateur breeders were introducing flowers with flakes of a different colour on a white background, flowers edged in a different colour (picotee), and flowers with two different colours on each petal.
  • The modern florist's, or perpetually flowering, carnation was first bred in the United States in the 1900s. The large, mostly scentless flowers became a staple of the cut-flower trade.
  • Florist's and border carnations are forms of Dianthus caryophyllus, that is native to Europe's Pyrenee Mountains.
  • The name carnation is now reserved for perpetual-blooming greenhouse varieties, hardy border forms, and old-fashioned Malmaison carnations.

Planting border carnations

All border carnations flower prolifically from midsummer until frost.

  • Grown in the open garden, either in a massed bed or in a border with other plants, they grow best in a slightly alkaline soil.
  • Plant in spring or fall, where they are to flower, in soil that has been well worked, enriched with compost or old manure, and allowed to settle.
  • Do not protect before the ground is frozen, as this may give rise to stem rot.
  • In early winter, evergreen boughs can be laid over the plants to help trap snow. In spring, as the stems start to grow, tie them to thin bamboo canes, but do not pinch out the growing tip, as you would for perpetual-flowering carnations.
  • Plants can be disbudded to give larger flowers. If this is done, remove only the bud beside the terminal one the first year or all buds may abort.

Growing border carnations from seed

Annual varieties will bloom in July if sown indoors about 10 weeks before the last frost.

  • Freeze the seed for one week, then sow on a sterilized seed mix.
  • Germination is fastest if seeds can be given warm days (21°C or 70°F) and cooler nights (16°C or 60°F).
  • When seedlings have two true leaves, transplant into small pots and grow in a sunny window or under fluorescent lights. Seed can be sown directly outside one week or so before the average last frost date, but will not begin to bloom as early.
  • Germination is improved if the seed is frozen first.
  • Biennial varieties can be sown indoors in late winter. Germination should take less than a week if the seed is kept cool (10°C or 50°F) after sowing. After germination, grow seedlings on in pots for hardening off and planting outdoors in early spring. After flowering, cut them back.
  • Alternatively, seed can be sown outside in June and will overwinter and bloom the following year. Sow thinly where you want them to flower or in a nursery bed and transplant in early fall.

Planting seedlings

Make sure the plants have been fully hardened off.

  • Water all potted plants an hour before planting. Dig a hole deep enough to take the root ball, and dust a little general-purpose fungicide into the hole. Set the plant in place and fill the hole. Firm with the fingers, leaving a slight depression, and water well.
  • Space plants 38 to 45 centimetres (14 to 18 inches) apart in the border. In a cutting garden, they can go 30 centimetres (12 inches) apart in rows. As they grow, tie them to thin canes.

That doesn't sound too difficult, does it? Now you know how to grow your own border carnations so you can brighten up your garden. Time to get digging!

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