Gadenin日本語Get the appChoosing a method
The plant's habit decides which method suits you. Because it throws new canes from a spreading crown rather than building a single trunk, an established clump can simply be split, and each division arrives with roots already attached and a full season's head start. That makes division the default choice whenever an existing plant is big enough to divide.
Cuttings are the right method when you want several plants from one you do not wish to disturb, or when you only have access to a shoot rather than a whole plant. Seed is worth doing when you have a plant carrying a heavy crop of ripe berries and the patience for the slow start, and it produces far more plants than the other two methods combined.
| Method | Best time | Time to a usable plant | Reliability |
|---|---|---|---|
| Division of an established clump | Early spring, before growth extends | One season | High, if each piece keeps roots and canes |
| Softwood or semi-ripe cuttings | Late spring through late summer | One to two seasons | Moderate; needs steady warmth and humidity |
| Seed from ripe berries | Sown as soon as the berries are fully colored | Two to three seasons | Variable germination, but large numbers |
Division, step by step
Divide in early spring, in the same window as the annual pruning, before new canes begin to extend. A clump three years old or more will divide comfortably into two or three pieces; a younger plant is better left alone for another year.
- Water the plant thoroughly the day before A well-hydrated plant handles the shock far better than a dry one, and the rootball holds together instead of crumbling when you lift it. This one step matters more than anything else in the process.
- Lift the whole plant with a fork Work a fork in a full 8 inches (20 cm) out from the canes on all sides and lever the clump up rather than pulling it by the stems. Keep as much of the fine root as you can; this plant does not enjoy being stripped bare.
- Split the crown by hand where you can Shake off the loose soil and pull the crown apart at its natural divisions. Use a clean knife only where the crown will not yield to hands. Each piece must carry at least three or four canes and a proper share of roots.
- Trim off anything dead or damaged Cut away broken roots and any blackened or dead canes. Do not shorten the healthy canes; they carry the leaves that will drive the recovery, and their tips carry the coming season's flower spikes.
- Replant immediately at the same depth Get the divisions back into improved, humus-rich soil or into pots the same day. Set them at the depth they were growing before, firm gently by hand and water in thoroughly.
- Keep them shaded and evenly damp for a full season A fresh division has a reduced root system and cannot cope with drying out. Deep shade, 2 inches (5 cm) of mulch and a thorough watering every 5 to 7 days in dry weather see it through the first summer.
Do not feed a new division. It has more top growth than roots and fertilizer at this point pushes soft canes it cannot support. Wait until the following spring, once new basal canes have come up, before any feeding.
Cuttings
Take cuttings from the warm months onward, using shoots that are firm at the base and still soft at the tip. Cut a length of 4 to 5 inches (10 to 13 cm), remove the leaves from the lower half, and shorten the remaining leaves by half if they are large, which cuts water loss without removing the plant's ability to feed the new roots.
Insert them into a free-draining mix of equal parts peat-free compost and perlite or sharp sand, several to a pot, with the leaves clear of the surface. Water once to settle the mix, then cover with a clear bag or a propagator lid held off the foliage. Keep them in bright shade with no direct sun and a steady temperature around 68 to 75F (20 to 24C).
Rooting takes six to ten weeks. Resist pulling at the cuttings to check; instead watch for new growth at the tip, which is the first honest sign that roots have formed. Once they are growing, ventilate the cover gradually over a week or two rather than removing it in one go, or the cuttings wilt before their roots can keep up.
Pot rooted cuttings individually into 3 to 4 inch (8 to 10 cm) pots and grow them on in shade for their first full season. They are small and easily lost, so keep them together in one place rather than distributing them around the garden, and protect them from any frost in their first winter regardless of how hardy the parent plant is.
Growing from seed
Collect berries when they are fully colored and slightly soft. Squash the flesh off under running water and rub the seed clean; the pulp contains germination inhibitors and left in place it will hold the seed dormant or rot it. Sow the cleaned seed at once, because it loses viability quickly on drying and stored seed germinates far more erratically than fresh.
Sow into trays of moist, free-draining seed-starting mix, covering the seed with about a quarter inch (5 mm) of mix. Keep the trays in a cool shaded place, protected from frost but not warm, and never let the surface dry out. Germination is slow and uneven, taking anywhere from a couple of months to a full season, and it is normal for seedlings to keep appearing long after the first flush.
Prick seedlings out into individual small pots once they have two or three pairs of true leaves, handling them by a leaf rather than the stem. Grow them on in shade with steady moisture. Expect two to three seasons before a seedling is a plant of any presence, and rather longer before it carries a worthwhile crop of berries.
Seedlings vary. Grown side by side from one parent, they will differ noticeably in leaf size, vigor, how densely they cane up and how heavily they fruit. That variation is the reason to raise a batch rather than one or two: it lets you keep the best and discard the rest at the end of the second year.
Records worth keeping
Write down the date each batch was started, the method used and where the material came from, and attach a label that will still be readable in two years. Plastic labels written in pencil outlast anything written in ink, and a batch of unlabelled shaded pots becomes indistinguishable within a season.
For cuttings, note the date they were taken, the state of the wood, the temperature they were kept at and the date the first tip growth appeared. Rooting success on this plant varies considerably with the firmness of the shoot, and two or three seasons of dated notes will tell you the exact stage that works in your conditions far better than any general rule.
For seed, record the date of collection and sowing and then the date of every flush of germination, not just the first. Because the seed comes up over months, a record of when the bulk appeared tells you how long to keep a tray that looks empty, which is the single most common reason viable seed gets thrown away.