Gadenin日本語Get the appCuttings are the easiest method by a long way
Portulaca stems are succulent and full of stored water, and they root faster than almost anything else you will grow. A piece broken off by a hose and left lying on warm gravel will often have roots within a week without any help at all. Deliberately taken cuttings root in three to seven days in summer and are flowering plants inside six weeks, which makes this the sensible way to multiply a plant you like or to rescue one that is rotting at the base.
The best material is a non-flowering shoot tip two to four inches (5 to 10 cm) long, firm rather than floppy, taken in the morning from a plant that has not just been watered. Flowering tips work but put their energy into the bloom first, so pinch the flowers and buds off before you stick them. Every piece you remove during a mid-season shear or a routine pinching is usable material.
The one step people skip is the drying. Succulent cuttings pushed straight into damp soil rot at the cut end. Leaving them on a dry surface for a day so the wound seals is the difference between a full tray and a tray of mush, and it costs nothing.
- Cut a shoot tip two to four inches long Use a clean sharp blade rather than pulling the stem, and cut just below a point where leaves join the stem. Choose firm growth from a plant that is dry at the roots; a cutting taken from a freshly watered plant is swollen with water and rots more readily.
- Strip the lower leaves and remove any flowers Take the leaves off the bottom inch (2.5 cm) so that no foliage will sit below the soil surface, and pinch off open flowers and fat buds. Anything left buried will rot, and anything flowering diverts energy that should be going into roots.
- Let the cut end dry for a day Lay the cuttings on newspaper or an empty tray somewhere warm, dry and out of direct sun for twenty-four hours until the cut surface has sealed and looks dull rather than wet. Skip this and stem rot is the usual result.
- Push them into gritty, barely damp mix Use about half potting mix and half grit, sand or perlite, filled into a shallow tray or small pots. Make a hole with a pencil, insert the cutting an inch (2.5 cm) deep, and firm lightly. No rooting hormone is needed. Space them so the leaves are not touching.
- Keep warm, bright and almost dry Stand them in bright light out of the fiercest midday sun, at around 70 to 80F (21 to 27C). Do not cover them with a propagator lid or a bag; the trapped humidity that helps other cuttings will rot these. Water very sparingly, only if the leaves begin to wrinkle.
- Check for resistance after a week Tug a cutting gently. Resistance means roots. Once rooted, move each into its own small pot of gritty mix or plant straight out if the ground is warm, and begin treating it as an adult plant: full sun, no feed, water only when the leaves soften.
Keeping plants through the winter
Portulaca is killed outright by frost, so anywhere with a cold winter it is grown as an annual. If you want the same plants again, take cuttings in late summer while the weather is still warm, root them, and keep the young plants indoors on the brightest windowsill you have, or under a grow light, at normal room temperature.
Overwintered plants need almost no water. Once a fortnight, and only when the leaves have gone soft, is about right in a cool bright room; more than that and they rot in the low light of midwinter. Expect them to look thin and stretched by late winter, because indoor light is nothing like what they want. That is not a failure, and they recover quickly.
In late winter or early spring, cut the stretched growth back hard and use the tips as a fresh round of cuttings. Those young plants, hardened off gradually once nights are reliably above 50F (10C), will be far better than the leggy parents and will be flowering by early summer.
Saving your own seed
After a flower closes, the base swells into a small round capsule. When it ripens, the top of the capsule comes away like a tiny lid and releases a large number of very fine seeds, dark gray to black and roughly the size of ground pepper. The capsules ripen unevenly over weeks, and once the lid lifts the seed is gone within days, so timing matters more than technique.
Collect by tipping whole stems into a paper bag once the capsules have turned papery and pale but before they open, or by holding a bowl underneath and tapping. Dry the collected material for a week somewhere warm and airy, then rub it between your fingers and separate the seed from the chaff by tipping it gently between two containers. The seed is small enough to blow away, so do this indoors.
Store dry seed in a paper envelope somewhere cool and dark. It stays viable for several years. Be aware that seed saved from a mixed planting will not come true to the colors you had, since the flowers cross freely; if you save seed year after year the population usually drifts towards a narrower and often less refined range of colors, and the flowers tend to get simpler.
| Method | When to do it | Time to a flowering plant |
|---|---|---|
| Stem cuttings | Any warm spell through summer | Roots in three to seven days, flowering in about six weeks |
| Cuttings for overwintering | Late summer, before nights cool | Held indoors, planted out after the last frost |
| Saved seed sown indoors | Late winter to early spring | Flowering roughly ten to twelve weeks from sowing |
| Saved seed sown direct | Once the soil is above 70F (21C) | Flowering in about eight to ten weeks |
| Self-sown seedlings | They appear on their own in late spring | Flowering by midsummer with no work at all |
Self-sown seedlings, and what to write down
Portulaca seeds itself readily into exactly the places it likes: gravel drives, the cracks between paving slabs, the gritty edges of paths, the surface of neighboring pots. Those volunteers are usually stronger than anything you raise in a tray, because they germinate when the ground is warm enough and grow without check. Lift them carefully with a trowel while they are small and move them where you want them, or leave them where they are.
Where you do not want them, they pull out in seconds while young. The only planting that genuinely gets away is one on open gravel that is never walked on, and even then the seedlings are shallow-rooted and easy to remove. If you want to prevent seeding altogether, shear the plants over before the capsules ripen rather than trying to pick capsules off individually.
Record the date you took cuttings and the date they rooted, and the position of any self-sown patch. The rooting date tells you how late in the season cuttings still work in your climate, and the map of volunteers tells you which surfaces in your garden this plant genuinely wants, which is usually the best guide to where to plant it deliberately.