Gadenin日本語Get the appCuttings are the easy route, and they are fast
Torenia stems are soft, hollow-ish and full of water, and they root readily. A tip cutting taken in warm weather will show roots in seven to fourteen days, which is quicker than most bedding plants and quick enough that you can take cuttings in midsummer and have flowering plants by late summer. Cuttings also give you an exact copy of the plant, which seed will not, so if you have a color you like this is the only reliable way to keep it.
Take material from the tips of non-flowering shoots if you can find them, or from flowering shoots with the buds pinched off. A cutting should be 3 to 4 inches (8 to 10 cm) long with three or four pairs of leaves. Cut cleanly just below a leaf joint, strip off the lowest pair of leaves, and pinch out the growing tip so the cutting puts its effort into roots rather than into extending.
Take cuttings in the morning while the stems are full of water, and get them into compost or water within minutes. A torenia cutting left lying on a bench in the sun for half an hour is limp and will root badly if at all. If you are collecting from several plants, carry a bag with a damp cloth in it.
- Take 3 to 4 inch (8 to 10 cm) tip cuttings in the morning Cut just below a leaf joint on a healthy non-flowering shoot. Choose stems that are firm rather than the softest new growth at the very tip, which collapses before it roots.
- Strip the lowest leaves and remove any buds Take off the bottom pair of leaves so a clean length of stem goes into the compost, and pinch out flower buds. A cutting trying to flower is not making roots.
- Insert into open, damp compost Use a mix of about half all-purpose potting mix and half perlite or sharp sand. Push the cuttings in an inch (2.5 cm) deep around the edge of a small pot, three or four to a pot, and firm gently.
- Keep humid, warm and shaded Cover with a clear bag held off the leaves by sticks, or use a propagator lid, and keep at 70F (21C) in bright shade. Direct sun under a bag cooks cuttings within an hour.
- Ventilate daily and watch for rot Open the cover for a few minutes each day to let condensation clear. Remove any cutting that goes soft or brown at the base immediately, before it takes the others with it.
- Check for roots after a week A gentle tug that meets resistance means roots. At 70F (21C) most cuttings are rooted in 7 to 14 days. Once rooted, take the cover off over two or three days rather than all at once.
- Pot up individually and pinch Move each rooted cutting into its own 4 inch (10 cm) pot, grow on in bright shade, and pinch the tip once it has made three or four new leaf pairs so it branches into a proper mound.
Rooting in water, and its one drawback
Torenia cuttings will root in a glass of water on a shaded windowsill, and they do it fast and visibly, which makes it a satisfying way to do it. Strip the lower leaves, stand three or four stems in an inch or two (3 to 5 cm) of water, keep the water out of direct sun and change it every couple of days, and you will see white roots within a week or so.
The drawback is that water roots are brittle and structurally different from compost roots, and a cutting left until it has a big tangle of them often sulks badly when it is finally potted. Move them into compost as soon as the roots are half an inch (12 mm) long, keep them shaded and humid for the first few days after potting, and they establish without a check. Left for a month in water they will still transplant, but you lose a fortnight to the setback.
Layering, and overwintering stock plants
Trailing and sprawling torenia layers itself without any help. Where a stem lies flat on damp soil it roots at the leaf joints, and by late summer a well-grown plant may have several rooted sections along its outer stems. Scrape the mulch away, look under the outer growth, and if you find roots, sever the stem on the parent side, lift the rooted piece with a trowel and pot it up. It is the least effort of any method and it gives you an established plant immediately.
To keep a plant through a frosty winter, do not try to overwinter the whole thing. Take cuttings in late summer, well before nights get cold, root them, and keep the young plants in small pots on a bright windowsill at no less than 55F (13C) with the compost barely damp. They will look thin and unimpressive all winter. In early spring, cut them back hard, pot them up, start feeding, and each one will give you several more cuttings to bulk up before planting-out time.
| Method | Best timing | Time to a usable plant | Comes true to the parent |
|---|---|---|---|
| Tip cuttings in compost | Early to late summer, while growth is soft | 3 to 5 weeks to a potted plant | Yes |
| Cuttings in water | Early to late summer | 1 to 2 weeks to roots, then pot on | Yes |
| Layering rooted stems | Late summer, on sprawling plants | Immediate, lift and pot | Yes |
| Cuttings for overwintering | Late summer, before cold nights | Held small over winter, bulked up in spring | Yes |
| Saved seed | Collect ripe capsules in late summer | 8 to 10 weeks from sowing to planting out | No, colors segregate |
| Self-sown seedlings | Appear in early summer where soil is warm | Flower late in the season | No, and usually fewer |
Saving seed, and self-sown seedlings
After each flower drops, a small green capsule swells at the base of the calyx. Leave them on the plant until they are dry, papery and pale brown, then snip the whole stem into a paper bag and let it finish drying indoors for a week before tapping the seed out. The seed is dust-fine, so work over a sheet of paper indoors with no draft, and store it dry, cool and dark in a paper envelope inside a sealed jar.
Be clear about what you are getting. Most garden torenia is grown from bred seed strains, and seed saved from your plants will not reproduce the parent's color or compactness. What comes up is a mixed batch, often taller and looser, with a wider and muddier range of colors. That can be perfectly pleasant for filling a shaded corner, but if you want the plant you actually had, take cuttings.
In a warm garden torenia will also seed itself. The seedlings appear in early summer once the soil is properly warm, which is late enough that they flower only in the last part of the season. They are easy to spot and easy to move while tiny, and easy to hoe off if you do not want them. Torenia is not aggressive and a stray patch is never a problem, but it is worth knowing which corner of the garden it favors.
When you take cuttings, label them with the date and the parent plant's position and color. By the following spring you will not remember which windowsill survivor came from the good plant by the shaded door and which came from the one that never did much.