How to Propagate Vinca from Cuttings and Seed

Two routes, and when each makes sense

Madagascar periwinkle can be increased either from tip cuttings taken off a growing plant or from seed. Cuttings are quicker, give you an exact copy of the plant you liked, and are the practical way to carry a favorite plant through winter in a frost-free room. Seed is slower and needs an early start under cover, but it is the only sensible route if you want a large number of plants for bedding.

Both routes fail in the same way for the same reason. This is a tropical plant, and cuttings that sit cool or cuttings that sit soaking wet rot instead of rooting, exactly as garden plants rot in cold spring soil. Warmth plus a barely-moist medium is the whole technique.

Whichever route you use, wash your hands afterwards. The sap is an irritant and the plant is toxic if any part is swallowed, so keep the propagating tray out of reach of children and pets rather than on the kitchen windowsill.

Taking tip cuttings

Expect a good proportion to take. Warm conditions and a gritty mix routinely give three quarters or more rooting successfully, while cuttings kept cool or wet often give none at all, which is why the same person can have wildly different results in two consecutive years.

Late-summer cuttings are the ones worth taking if you want to keep a plant going. They root while it is still warm, are small and easy to overwinter on a bright frost-free windowsill kept nearly dry, and give you a plant ready to grow away as soon as spring warmth arrives.

1. Choose the right shoots Take non-flowering tips about three to four inches (8-10 cm) long from healthy growth in warm weather. Soft new tips root fastest; woody stems from the base of an old plant root poorly and slowly. If every shoot is carrying buds, pinch a few tips a fortnight beforehand to force clean vegetative shoots.
2. Prepare the cutting Cut just below a leaf pair with clean snips and strip the lower leaves so the bottom inch and a half (4 cm) of stem is bare. Remove any flower buds; a cutting trying to flower will not put its energy into roots. Leave two or three leaves at the top and halve very large ones to reduce water loss.
3. Insert into a gritty mix Use a free-draining mix of about half potting mix and half perlite or sharp sand, moistened and then allowed to drain fully. Push cuttings in around the edge of a small pot, three or four to a four-inch (10 cm) pot, firming just enough to hold them upright. Rooting hormone is optional and makes little difference.
4. Keep them warm, bright and only just moist Aim for 70-75F (21-24C) with bright indirect light. A propagator or a clear bag supported off the leaves keeps humidity up, but vent it daily so condensation does not sit on the foliage. Water only when the surface has dried; sodden mix is the usual cause of blackened stems.
5. Check for roots after two to three weeks A gentle tug that meets resistance means roots have formed, which usually takes fourteen to twenty-one days in warm conditions. Once rooted, remove the cover gradually over several days rather than all at once, so the cuttings harden to normal humidity.
6. Pot up and pinch Move each rooted cutting into its own three-inch (8 cm) pot of ordinary free-draining compost and grow it on warm and bright. Pinch the tip once the plant has four or five leaf pairs to force branching, and plant out only once nights are reliably above 55-60F (13-16C).

Growing from seed

Seed needs an early start because this plant is slow at the beginning: expect around twelve to sixteen weeks from sowing to a plant ready to go outside, so sow under cover well before the frosts end. Germination itself needs steady heat of 75-80F (24-27C) and darkness, so cover the seed lightly with mix and keep the tray in the dark or under a cover until the seedlings appear, usually in one to two weeks.

After germination, move the tray straight into strong light and drop the temperature slightly to around 70F (21C). Seedlings kept warm but dim stretch immediately and never make good plants. Water from below where you can, let the surface dry between waterings, and keep airflow moving, because damping off takes out crowded wet seed trays quickly.

Saved seed from your own plants germinates well but will not reproduce a bought plant exactly, since most garden plants are hybrids and their seedlings vary in color and habit. If that variation is fine with you, collecting seed costs nothing: let a few pods dry on the plant late in the season, catch them before they split, and store the seed dry and cool in a labeled envelope.

Keeping notes that make next year easier

Write down the date you sowed or took cuttings, the temperature you kept them at, and the date they were ready to plant out. That one chain of dates is what tells you whether to start earlier or later next year, and it is far more useful than any general timing advice, because it is measured in your own conditions and your own windowsill.

Also record how many cuttings you took and how many rooted. A poor strike rate almost always traces to one of two things you can identify from your own notes: the medium stayed too wet, or the temperature dropped at night. Once you know which it was, the following year's batch usually takes cleanly.