Gadenin日本語Get the appHow the year is shaped
This plant has a simple annual arc with one decision that dominates everything: when to put it outside. Seed goes in under cover in late winter or very early spring, plants grow slowly indoors for three months or so, they go out only once real summer warmth has arrived, they flower without interruption through the hottest weeks, and the first frost ends them. Everything else is minor by comparison.
Because the plant does nothing useful until it is warm, the calendar is anchored to temperature rather than to dates. In a cool late spring the whole schedule shifts back by a fortnight and no harm is done; in an early warm year everything moves forward. Reading the thermometer and the forecast beats reading any fixed timetable.
The stages below use seasons rather than months so they read the same in either hemisphere. Fit them to your own last and first frost dates, and to how quickly your soil warms, which varies enormously between a raised sandy bed and heavy ground in shade.
The season stage by stage
Work through the table below as the season progresses, and take the temperature triggers seriously. The two that matter most are soil above 65F (18C) at planting time and the first frost warning in autumn.
| Stage | Trigger | What to do |
|---|---|---|
| Sow under cover | 12-16 weeks before you expect settled warm nights | Sow into moist mix, cover lightly, hold at 75-80F (24-27C) in the dark until germination |
| Seedling stage | As soon as shoots appear | Move into strong light at around 70F (21C); water from below and keep the surface dry between waterings |
| Potting up | At two or three leaf pairs | Move to individual 3 in (8 cm) pots of free-draining mix; keep warm and bright |
| Pinch | At four or five leaf pairs | Take out the growing tip to force branching; expect a short pause afterwards |
| Harden off | Once days are warm and settled | Stand outside in a sheltered spot on warm days for 7-10 days; bring in on cold nights |
| Plant out | Night lows above 55-60F (13-16C), soil above 65F (18C) | Plant 10-12 in (25-30 cm) apart on free-draining ground, crown slightly proud |
| Establishment | First 2-3 weeks after planting | Water lightly only when the top inch is dry; do not feed; ignore slow growth |
| Main flowering | Through the hottest weeks | Water only when dry, feed lightly once a month in pots, clear debris from the mound |
| Midsummer refresh | If plants go leggy or open in the center | Pinch stem tips back 2-3 in (5-8 cm); allow 2-3 weeks to rebuild |
| End of season | First frost warning | Bring pots under cover if you want to keep them; otherwise clear beds and note what failed |
Spring: resist the urge to plant
Spring is the part of the calendar people get wrong. Plants appear in shops long before the ground is ready, the weather has a warm week, and out they go into soil that is still cold below the surface. The result is a bed that sits still for a month and loses a third of its plants to stem rot.
Hold your nerve. Keep bought or home-grown plants in their pots somewhere warm and sheltered, water them sparingly, and pot them up into a slightly larger container if the wait stretches out. A plant held in a warm pot for an extra fortnight is in far better shape than one planted early into cold ground.
Use the wait productively by preparing the ground: work grit into heavy soil, decide on spacing, and check that the spot really does get six to eight hours of direct sun now that surrounding plants have started into growth. Beds that looked sunny in early spring are often shaded by the time this plant goes out.
The single most useful entry in your records is the date you planted out, next to the night temperatures that week and a verdict on how the plants performed. Two seasons of that and you will know your own correct planting week.
Summer: almost nothing to do
Once established in warm soil, this is a plant you can largely leave alone. There is no deadheading, because spent flowers drop cleanly by themselves. Feeding is light and occasional. Watering is only when the soil has genuinely dried, which in a bed may be once a week or less even in a hot spell.
The only regular job is a quick look every couple of weeks: pull dead leaves out of the center of each mound, check the stem bases for any darkening after wet weather, and pinch back anything going leggy. Five minutes across a whole bed is enough.
This is also when the plant earns its place. Through the weeks when other bedding is flagging in the heat, a well-sited vinca is at its densest and most colorful, so keep it in the position that suits it rather than moving it somewhere more convenient.
Autumn: ending it and recording it
Flowering continues right up to the first frost, which kills the plant outright. If you want to carry a particular plant over, take tip cuttings in late summer while it is still warm and overwinter the rooted young plants on a bright frost-free windowsill, kept nearly dry. Lifting a whole mature plant indoors is possible but rarely worth the space.
When frost has taken the bed, clear the plants and wear gloves doing it, since the whole plant is poisonous if eaten and the sap can irritate skin. Note which positions did well and which lost plants, and whether the losses were in the damp corners, because that is the information that shapes next year's planting plan.
Finish the year by writing down three dates: sowing or purchase, planting out, and the frost that ended it. That is the complete cycle in three lines, and it makes the following spring's judgement call much easier than starting from memory.