Gadenin日本語Get the appWhat a good young plant looks like
A carnation seedling worth growing on is short-jointed, gray-green, and stiff enough that the stem does not bend under its own weight. The pairs of leaves should be close together, a fraction of an inch apart, and the plant should look slightly stunted rather than lush. That is the correct appearance, and gardeners who push their seedlings with warmth and feed to get something that looks generous end up with soft plants that flop, rot at the base and flower poorly.
The opposite, a seedling with long gaps between the leaf pairs and a pale floppy stem, has been grown too warm or too dark, usually both. This cannot be corrected later. The stretched section stays stretched, and the plant carries that weak lower stem for its whole life. Move seedlings into the brightest and coolest place you have the moment you see the joints starting to lengthen.
Roots tell you the rest. Tip a seedling out of its cell and you want white roots working around the outside of the plug without matting into a solid mass. A plug that is already a hard tangle of root has been left too long and will check badly when planted. One where the compost falls apart is not ready to move.
Temperature, light and water in the first weeks
Carnations germinate around 65 to 70F (18 to 21C), but that is a germination temperature, not a growing temperature. Once the seedlings are up, drop them to 50 to 60F (10 to 16C) and give them the brightest light available. Cool and bright is the whole recipe. Held at germination warmth for another three weeks, they stretch, and there is no recovering from that.
Water sparingly and always from below where you can. Stand the tray in shallow water until the surface darkens, then take it out and let it drain completely. Carnation seedlings damp off readily, and a surface that stays wet between waterings is the direct cause. Water in the morning so that everything is dry by evening, and thin or space the plants so that air moves between them.
Do not feed for the first few weeks. Seed-starting mix carries enough for the early stage, and a young carnation given nitrogen too soon puts on soft growth exactly when you want it firm. Once seedlings are in their own pots and growing steadily, a balanced liquid feed at quarter to half strength every two weeks is plenty.
| Stage | Temperature | Container | Watch for |
|---|---|---|---|
| Germination | 65 to 70F (18 to 21C) | Seed tray or cells, barely covered | Seedlings appear in seven to fourteen days |
| First true leaves | 50 to 60F (10 to 16C), brightest light available | Same tray, thinned to one per cell | Stretching joints, damping off at the soil line |
| Two to three pairs of leaves | 50 to 60F (10 to 16C) | Three inch (8 cm) pot of gritty mix | Roots circling the plug; move before they mat |
| Six to eight pairs of leaves | 50 to 60F (10 to 16C) | Same pot until roots fill it | This is the moment to pinch out the tip |
| After the pinch | Cool, outside in a sheltered place once frost has passed | Four to five inch (10 to 13 cm) pot or final position | Side shoots breaking from the joints below the pinch |
The pinch that builds the plant
The single most important thing you do to a young carnation is stop it. When the plant has made six to eight pairs of leaves, take out the growing tip so that the shoots below it break instead. Those side shoots are what carry the flowers. A plant that is never pinched grows straight up, produces one flower at the top, and then sits there having spent the season on a single bloom.
Take the tip out with finger and thumb rather than with tools, snapping it cleanly just above a leaf joint. The tissue at that stage is soft and comes away easily, and there is no wound worth worrying about. Aim to leave five or six pairs of leaves on the plant below the pinch, because each of those joints is a potential shoot.
Expect side shoots to show within two to three weeks. On strong plants some growers stop those shoots again once they have made four or five pairs of leaves, which builds a bushier plant with more but slightly smaller flowers. On a first attempt, one pinch is the right choice; the second stop is worth trying only once you know how vigorous your plants are on your own site.
- Count the leaf pairs Wait until there are six to eight pairs on the main stem. Pinching earlier than that leaves too few joints to break; much later and the plant has already committed to height.
- Snap out the tip Hold the stem below and bend the soft growing tip sideways with finger and thumb just above a leaf joint. It should come away cleanly without crushing the stem.
- Keep conditions cool and bright afterwards The plant will push side shoots over the next two to three weeks. Warmth at this point produces long weak shoots, so keep it cool and in full light.
- Do not pinch a budded plant If the tip already holds a visible flower bud, leave it. Pinching then simply removes the flower and the plant will not branch any better for it.
Hardening off and planting out
Carnations harden off easily because they have been grown cool from the start, but they still need the transition. Put the pots outside in a sheltered spot out of direct midday sun for a few hours a day and increase the exposure over a week to ten days, bringing them in at night to begin with. The thing to watch for is wind rather than cold, because a young carnation stem snaps at a joint just as readily as a mature one.
Plant out once the risk of hard frost has gone, into full sun on gritty, free-draining, neutral to slightly alkaline soil. Set each plant at exactly the depth it grew at in the pot. Planting even half an inch too deep buries the collar and is a common cause of losing young plants to rot in their first autumn. Space them a foot to fifteen inches (30 to 38 cm) apart so that the foliage will not touch at full size.
Water in well, then leave them. New plants need enough water to establish over the first two or three weeks, but a young carnation kept constantly moist grows soft. Once you can see new growth from the center, the plant has taken hold and can go on to the normal regime of watering at the base only, when the surface has dried.
Never sow or grow carnation seedlings expecting them to match a parent plant. Seed does not come true, so a batch raised from a favorite plant gives a range of colors and forms, most of them different and some of them poor. To keep a specific plant you have to take cuttings from it.
What to record from a batch of young plants
Write down the sowing date, the date the seedlings emerged, the date of the pinch, and the date the side shoots broke. Those four intervals are the ones that repeat every year, and once you know them for your own conditions you can work backwards from when you want flowers and sow at the right moment rather than guessing.
Then keep a note of how many plants you started with and how many made it to planting out. Losses between those two numbers are almost always damping off or stretching, and both are conditions you set rather than accidents. A record showing that you lose a third of every batch is what finally makes it worth moving the tray somewhere cooler and brighter.